TECHNICAL MANUAL
OPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT, AND
GENERAL SUPPORT MAINTENANCE MANUAL
(INCLUDING REPAIR PARTS AND SPECIAL TOOLS LISTS)
FOR
METER, AUDIO LEVEL TA-885/U
(HEWLETT-PACKARD MODEL 3555B)
(NSN 6625-00-255-1083)
HEADQUARTERS, DEPARTMENT OF THE ARMY
11 MARCH 1980
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SECTION
III. OPERATING INSTRUCTIONS (Cont.).
Para
Page
Crosstalk measurements................................................................................................... 3-53
Identifying noise characteristics......................................................................................... 3-57
Measurements in DBC ...................................................................................................... 3-64
Measurement procedures.................................................................................................. 3-67
150 BAL conversion .......................................................................................................... 3-69
IV. THEORY OF OPERATION
Introduction....................................................................................................................... 4-1
Block diagram description ................................................................................................. 4-7
Detailed circuit description................................................................................................. 4-16
Range attenuator A2 ......................................................................................................... 4-18
Input amplifier A3.............................................................................................................. 4-20
Filters................................................................................................................................ 4-25
Meter amplifier.................................................................................................................. 4-30
Detector............................................................................................................................ 4-32
Power supply and series regulator..................................................................................... 4-37
V. MAINTENANCE
Introduction....................................................................................................................... 5-1
Factory selected values..................................................................................................... 5-4
150 BAL conversion .......................................................................................................... 5-6
Performance Checks......................................................................................................... 5-7
Adjustment and calibration procedure................................................................................ 5-14
Assembly removal............................................................................................................. 5-25
Troubleshooting procedures .............................................................................................. 5-27
Factory selected values..................................................................................................... 5-39
VI. REPLACEABLE PARTS
Introduction....................................................................................................................... 6-1
Ordering information ......................................................................................................... 6-4
VII. CIRCUIT DIAGRAMS
Introduction....................................................................................................................... 7-1
Functional block diagrams................................................................................................. 7-3
Schematic diagrams ......................................................................................................... 7-5
A. REFERENCES..................................................................................................................
B. MAINTENANCE ALLOCATION
I. Introduction.......................................................................................................................
Il. Maintenance allocation chart for Meter, Audio Level TA-885/U...........................................
III. Tool and test equipment requirements for Meter, Audio Level TA-883/U ............................
IV. Remarks (Not applicable)
SECTION
APPENDIX C. MANUAL BACKDATING CHANGES..................................................................................
ii
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Model 3555B
Table of Contents
Page
LIST OF ILLUSTRATIONS
Page Number
Number
1-1. Model 3555B Transmission and
Noise Measuring Set.................................. 1-1
3-1. Front Panel Controls, Indicators,
and Connectors ......................................... 3-2
3-6. Typical Test Set-Up for Measuring
Insertion Loss .......................................... 3-10
3-7. Test Set-Up for Measuring
Crosstalk Coupling Loss .......................... 3-11
3-8. Simple Test for Inductive and
Capacitive Coupling................................. 3-12
4-5. 3kHz FLAT and PROGRAM
5-3. +20dBm and +30dBm Level
Accuracy Check............................................ 5-4
7-2. A1 Function Assembly Schematic and
Component Location............................... 7-5/7-6
7-3. A2 Range Attenuator and A3 Input
Amplifier Schematic and Component
Location.................................................. 7-7/7-8
7-4. A4 Filter Schematic and Component
Location................................................ 7-9/7-10
7-5. A3 Meter Amplifier, Detector and Series
Regulator Schematic and Component
Weighting Curves...................................... 4-5
4-6. C-MSG and 15kHz FLAT
Weighting Curves...................................... 4-6
LIST OF TABLES
Page Number
Number
Page
2-1 Suitable Batteries Meeting
5-3 Carrier 600 BAL and 135 BAL Level
NEDA 202 Specifications........................... 2-1
3-1 Front, Side and Rear Panel Controls,
Accuracy Check............................................ 5-3
5-4 VF/Nm Level Accuracy Checks 600 BAL
Indicators and Connectors ................... 3-3/3-5
and 900 BAL -80 dBm Through +30 dBm ..... 5-4
6-2 Part Number-National Stock Number
Cross Reference Index ............................... 6-10
iii
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SECTION 0
INTRODUCTION
0-1.
Scope
This manual contains instructions for the operation, organizational maintenance and general support maintenance of
Audio Level Meter TA-885/U. Throughout this manual, the equipment is referred to by its commercial designation of
Hewlett-Packard Model 3555B Transmission and Noise Measuring Set or simply as the 3555B. Appendix A of the
manual contains a list of references and appendix B contains the maintenance allocation chart (MAC).
NOTE
No direct support maintenance functions are authorized for this equipment.
0-2.
Indexes of Publications
a. DA Pam 310-4. Refer to the latest issue of DA Pam 310-4 to determine if there are any new editions,
changes, or additional publications pertaining to this equipment.
b. DA Pam 310-7. Refer to DA Pam 310-7 to determine if there are any modification work orders (MWO's)
pertaining to this equipment.
0-3.
Maintenance Forms, Records, and Reports
a. Reports of Maintenance and Unsatisfactory Equipment. Department of the Army forms and procedures
used for equipment maintenance will be those described by TM 38-750, The Army Maintenance Management System.
0-1
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b. Report of Packaging and Handling Deficiencies. Fill out and forward DD Form 6 (Packaging Improvement
Report) as prescribed in AR 700-58/NAVSUPINST 4030.29/AFR 71-13/MCO P4030.29A, and DLAR 4145.8.
c. Discrepancy in Shipment Report (DISREP) (SF 361). Fill out and forward Discrepancy in Shipment Report
(DISREP) (SF 361) as prescribed in AR 55-38/NAVSUPINST 4610.33B/AFR 75-18 MCO P4610.19C and DLAR 4500.15.
0-4.
Administrative Storage
Before placing the TA-885/U in temporary storage (90 days), determine the serviceability of the equipment by
0-5.
Destruction of Army Electronics Materiel
Destruction of Army electronics materiel shall be in accordance with the instructions in TM 750-244-2.
Reporting Equipment Improvement Recommendations (EIR)
0-6.
If your TA-885/U needs improvement, let us know. Send us an EIR. You, the user, are the only one who can tell
us what you don't like about your equipment. Let us know why you don't like the design. Tell us why a procedure is hard
to perform. Put it on an SF 368 (Quality Deficiency Report). Mail it to Commander, US Army Communications and
Electronics Materiel Readiness Command, ATTN: DRSEL-ME MQ, Fort Monmouth, New Jersey 07703. We'll send you
a reply.
0-2
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Section I
Model 3555B
Table 1-1. Specifications
VOICE FREQUENCY LEVEL MEASUREMENTS (20Hz
to 20kHz)
balanced and 75 ohms unbalanced.
Return loss: TERM ONLY
600 ohms: 26dB min 3kHz to 150kHz
135 ohms: 26dB min to 600kHz
75 ohms: 30dB min to 3MHz
Bridging loss: less than 0.05dB at 10kHz
Balance:
Range: -91dBm to +31dBm
Level accuracy: 20Hz to 20kHz: +0.5dB
40Hz to 15kHz: +-0.2dB
(Levels greater than -60dBm)
greater than 70dB to 10kHz
greater than 60dB to 100kHz
greater than 40dB to 600kHz
Note: For levels greater than +1 dBm, level accuracy
specification applies only for frequencies above
100Hz.
GENERAL
Input: will terminate or bridge 600 ohms or 900 ohms
balanced.
Temperature range: 0°F to 120°F 0 to 95% relative
humidity
Bridging loss: less than 0.3 dB at 1kHz.
Return loss: 30dB min. (50Hz to 20kHz) TERM
Return loss: 30dB min. (50Hz to 2kHz) TERM
only.
The 3555B will operate at -40°F under reduced
specifications. At this temperature, attention
should be given to noting condition of battery as
indicated on Battery Test (DIAL/BAT).
Balance:
greater than 80dB at 60Hz
Meter: linear dB scale indicates rms value of input
greater than 70dB to 6kHz
greater than 50dB to 20kHz
signal. 12dB range.
Meter response
Holding circuit: 700 ohms dc resistance, 60mA
max. loop current at 300Hz. With holding circuit
in, above specs apply from 300Hz to 4kHz.
Normal: 200ms to indicate a reading to 0dBm on
meter.
Damp: 500ms to indicate a reading to 0dBm on
meter.
NOISE MEASUREMENTS
Maximum input voltage
Range: -1 dBm to +121dBm
Tip to ring: 150V peak
Tip or ring to ground: 500V peak
(This is maximum instantaneous voltage. Input
circuit will withstand 48V dc CO battery with
superimposed 90V rms 20Hz ringing voltage or
±130V carrier supply.)
Weighting filters: 3kHz flat, 15kHz flat, C-message, and
program. Meets joint requirements of Edison
Electric Institute and Bell Telephone System.
Input: same as for level measurements.
Maximum longitudinal voltage: 200V rms at 60Hz
Noise to ground:
80 kilohms across line
100 kilohms to ground
-40dB relative to 600 ohms noise metallic at
1kHz.
AC Monitor: 0.27V rms for 0dBm on meter.
Rout = 8 kilohms. Available at DIAL/AC MON
jacks. Sufficient to drive WE 1011B or 52 type
headset.
DC Monitor: 1 volt for 0dBm on meter. Rout = 2
kilohms. Jack accepts 310 plug (tip negative).
CARRIER FREQUENCY LEVEL MEASUREMENTS
(30Hz to 3MHz)
Input jacks: will accept Western Electric (WE) 241,
309, 310, 358 plugs. Binding posts accept banana
plugs, spade lugs, phone tips or bare wires.
Removable shorting bar between sleeve and
ground binding posts.
Dial/AC Monitor jacks: will accept WE 289, 310, 347
plugs. Accepts WE 1011B lineman's handset or
52 type headset.
Range: -61dBm to +11dBm
Level accuracy:
600 ohms balanced
1kHz to 150kHz: ±0.5dB
135 ohms balanced (or 150 ohms balanced)
1kHz to 600kHz: ±0.5dB
10kHz to 300kHz: ±0.2dB
75 ohms unbalanced
Power requirements:
100Hz to 600kHz: ±0.2dB
Internal battery: single NEDA 202 45V "B"
battery included. Expected battery life - 180
hours at 4 hours per day at 70° F.
30Hz to 1MHz: ±0.5dB
1MHz to 3MHz: ±0.5dB ±10% of meter reading
in dBm.
AC: 115V or 230V, 48-440Hz, <1W
External battery: 24V or 48V office battery; jack
accepts 310 plug (tip negative) less than 15mA.
Input: will terminate or bridge 600 ohms or 135 ohms
1-0
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Model 3555B
Section I
SECTION I
GENERAL INFORMATION
provided, balanced or unbalanced, bridged or
terminated. For noise measurements a noise-to-ground
(Ng) function is provided which provides 40dB of
1-1.
INTRODUCTION.
The Hewlett-Packard
1-2.
Model
3555
B
attenuation for longitudinal noise.
For carrier
Transmission and Noise Measuring Set is a versatile set
designed for uses in testing telecommunications
equipment. The extreme sensitivity of this set, linked
with its wide and flat frequency response, make it
suitable for noise and level measurements at voice,
program and carrier frequencies. Levels from -80dBm
to +30dBm (10dBm to +120dBm) full-scale can be
measured and displayed on a meter calibrated to
indicate both in dBm for level measurements and in
dBm for noise measurements.
frequencies 600 ohm, 135 ohm and 75 ohm impedances
are provided. The 600 and 135 function can be either
balanced or unbalanced, bridged or terminated; The 75
function is unbalanced only. Bridging impedance is over
100 kilohms, allowing measurements with a bridging
loss of less than 0.05dB. The meter indicates in dBm
for any selected input impedance.
1-4.
The 3555B includes a 3kHz flat, a C-Message, a
Program and a 15kHz flat filter, each easily selectable
by a front panel control. These filters conform to the
standards set up .by the Bell System and Edison Electric
Institute. Other filters are available upon request.
1-3.
The set combines the features of a voice and
noise frequency measuring set and the features of a
carrier frequency measuring set. For voice and program
frequencies impedances of 900 ohms and 600 ohms are
Figure 1-1. Model 3555B Transmission and Noise Measuring Set
1-1
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Section I
Model 3555B
Table 1-2. Accessory Equipment Supplied
1-5.
A noise-to-ground (Ng) function is included
which permits the measurement of longitudinal noise.
When making noise-to ground measurements the
impedance between INPUT terminals is greater than 80
kilohms and is 100 kilohms between each terminal and
ground. A HOLD function permits holding the line while
-hp- Part No.
8120-1348
1470-0026
03555-26510
5000-7135
Description
Power Cord
Battery, 45 Volt dry cell
Test Board
Decal, 150 BAL
Quantity
1
1
1
1
noise measurements are being made.
The input
circuitry provides 40dB of longitudinal noise attenuation
when noise-to-ground measurements are being made.
1-11. INSTRUMENT IDENTIFICATION.
1-6.
A DIAL/BAT function permits connecting a
1-12. Hewlett-Packard uses
number. The first section (prefix) identifies a series of
instruments. The last section (suffix) identifies a
a
two-section serial
lineman's handset to the line for the purpose of dialing
and at the same time connects the front panel meter to
the power supply so that the battery voltage or
unregulated power supply voltage can be monitored.
particular instrument within the series. If a letter is
included with the serial number, it identifies the country
in which the instrument was manufactured. If the serial
prefix of your instrument differs from the one on the title
page of this manual, a change sheet will be supplied to
make this manual compatable with newer instruments or
manual to earlier instruments. All correspondence with
Hewlett-Packard should include the complete serial
number.
1-7.
Jacks accepting Western Electric type 241, 309,
310, 347, and 358 plugs are provided for INPUT
connections to the 3555B. Dual binding posts accept
banana plugs, wires, lugs or phone tips and a pair of
special connectors permit the attachment of clip leads
from a lineman's handset.
1-8.
The Model 3555B can be operated from either
the internal 45V dry cell battery or from the ac line, 115
or 230Vac, 48Hz to 440Hz. A special device is included
in the cover to automatically turn the set off when the
cover is replaced. The set can also be operated from
the central office battery. A jack is provided on the side
of the set for this purpose.
1-13. 150 BAL MODIFICATION.
1-14. The Model 3555B is shipped from the factory
with a 135 BAL function. If a 150 BAL function is
desired instead of the 135 BAL function, the set can be
converted by simply clipping a shorting wire within the
set, applying a 150 BAL decal (supplied with the set)
over the 135 BAL decal and making only one
adjustment.
1-9. ACCESSORY EQUIPMENT SUPPLIED.
1-10. The accessory equipment supplied with the
1-15. For detailed instructions on modification of the
within specification tolerances a simplified procedure
can be used to modify the set and is described in
1-2
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Model 3555B
Section II
SECTION II
INSTALLATION
Table 2-1. Suitable Batteries Meeting
NEDA 202 Specifications
2-1.
INSPECTION.
The set was carefully inspected both
2-2.
Manufacturer
Mfr. Part No.
1420-0026
KS-14370
BA-59
mechanically and electrically before shipment. It should
be physically free of mars or scratches and in perfect
electrical condition on receipt. To confirm this, the set
should be inspected for physical damage in transit, for
supplied accessories and for electrical performance.
is damage or deficiency, see the warranty in the front of
this manual.
Hewlett-Packard
Western Electric
Military
Eveready
Burgess
482
M-30
RCA
VS013
Bright Star
Mallory
3033-158, 30-33
M-202
Ray-O-Vac
Sears
202, P7830
6461
Wards
42
2-3.
WARRANTY EXCEPTION.
Wizard
Zenith
3B6241
2783
2-4.
The battery supplied with the 3555B is
General
Marathon
National Carbon
W30B
4202
482
warranted for a period of 60 days, beginning at the time
of receipt of the set. This warranty is based on an
expected battery life of 180 hours at 4 hours per day at
2-10. BATTERY.
2-5.
POWER REQUIREMENTS.
2-11. This set is operated from a single NEDA 202
45V dry cell internal battery or an external 48V CO
battery when the power selection switch, on the side of
the case, is in the DIAL/BAT position. Inserting a
Western Electric plug into the battery jack disconnects
2-6.
This set is designed to operate from an internal
45 volt dry cell battery, an external 24 to 48 volt CO
battery or from an ac power source (115/230V, 48 to
440Hz). The power source is selected by the AC/BAT
switch on the side of the, set. The line voltage is
selected by the 115/230 volt slide switch on the rear of
the set. The set is protected by a 0.1 5A slow-blow fuse.
suitable for use in this instrument.
2-7.
THREE-CONDUCTOR POWER CABLE.
2-8.
To protect operating personnel, the National
Electrical
Manufacturers'
Association
(NEMA)
recommends that the panel and cabinet be grounded.
This set is equipped with a three-conductor power cable
which, when plugged into an appropriate receptacle,
grounds the set. The offset pin on the power cable
three-prong connector is the ground wire. This power
cable is detachable from the set and is stored inside the
front cover.
2-9.
configurations that are used throughout the United
States and in other countries. The -hp- part number
shown directly below each plug drawing is the part
number for a 3555B power cord equipped with the
proper plug. If the appropriate power cord is not
included with the instrument, notify the nearest Hewlett-
Packard office and a replacement cord will be provided.
Figure 2-1. Power Plugs.
2-1
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Section II
Model 355B
POSITION TO PRESERVE BATTERY
LIFE. IF THIS IS NOT BINDING, THE
COVER FITS EASILY INTO PLACE.
2-12. INSTALLATION
BATTERY.
AND
REMOVAL
OF
2-13. To install or replace a battery, turn the four 1/4
turn fasteners on the battery cover on the rear of the
case counterclockwise to remove the cover. Lift off the
cover, lift the battery out of its recess and unplug the
three-prong connector.
2-17. REPACKAGING FOR SHIPMENT.
2-18. The following is a general guide for repackaging
at instrument for shipment. If you have any questions,
contact your local Sales and Service Office. (See
Appendix for locations.)
2-14. Reverse the above procedure when installing a
new battery.
a. Place instrument in original container if
available. If not available, one can be
purchased from your nearest -hp- Sales
and Service Office.
b. Wrap instrument in heavy paper or plastic
before placing in inner container.
c. Use plenty of packing material around all
sides of instrument.
d. Use a heavy carton or wooden box to
house the instrument and inner container
and use strong tape or metal bands to seal
the shipping container.
2-15. COVER REMOVAL.
2-16. To remove the cover from the instrument,
release the two spring latches on either side of the
instrument, then lift cover. When replacing the cover,
first check the latches for released position; then place
cover in position for latching. The power cord is stored
inside the cover by wrapping it around the retainer
fastened inside the cover.
CAUTION
e. Mark shipping container with "Delicate
Instrument" or "Fragile".
DO NOT FORCE COVER INTO
PLACE. THERE IS A PROJECTION
ON THE COVER WHICH TURNS THE
POWER SWITCH TO THE OFF
2-2
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Section III
Model 3555B
SECTION III
OPERATING INSTRUCTIONS
3-1.
INTRODUCTION.
The Model 3555B Transmission and Noise
arranged for -48V or -24V ±2V with the
negative terminal of the battery connected to
the tip and the ground terminal connected to
the sleeve. Current consumption by the
3555B is approximately 15mA.
3-2.
Measuring Set is an extremely versatile transmission and
noise measuring set which satisfies many of the
requirements in testing telecommunications equipment.
The 3555B features a choice of 900 or 600 ohms bridging
or terminated for voice frequencies and 600, 135 or 75
ohms bridging or terminate for carrier frequencies. Noise-
to-ground and noise Metallic may be measured with 3kHz
Flat, C-Message or 1 5kHz Flat weighting. A HOLD
function permits seizing the line while measurements are
being made at voice and program frequencies. The set is
portable and operates from the internal battery, office
battery or ac power source.
WARNING
DURING BATTERY OPERATION, THE
"G" BINDING POST MUST BE
CONNECTED TO EARTH GROUND.
CAUTION
THE CORD MUST BE CONNECTED TO
THE MEASURING SET BATTERY
JACK FIRST AND THEN PLUGGED
INTO THE BATTERY SUPPLY TO
AVOID SHORTING THE OFFICE
BATTERY TO GROUND.
3-3.
This section of the manual contains all the
information necessary in the operation of the 3555B along
with a description of all controls, connectors and
indicators.
c. Turn the POWER switch to ON and depress
the DIAL/BAT pushbutton on the FUNCTION
switch. The meter pointer should indicate in
the BAT GOOD area indicating that the
battery condition is good if the set is being
operated from the internal battery. The
meter will also monitor the ac supply voltage
or the external office battery voltage,
providing an indication of low voltage should
it exist. The voltage should cause meter
deflection above the lower end of the green
BAT GOOD area for proper set operation.
3-4.
INDICATORS.
CONTROLS,
CONNECTORS
AND
3-5.
describe the function of all front and side panel controls,
indicators and connectors.
3-6.
OPERATION.
3-7.
and perform the following steps:
3-8.
BATTERY.
a. Before connecting the 3555B to an ac power
source, insure that the 115/230 volt switch is
positioned to indicate the line voltage to be
used. Some earlier instruments did not have
the 115/230 volt selector switch. To change
these instruments, jumper wires must be
changed on the power transformer. Refer to
configurations.
3-9.
The internal dry cell battery has a voltage range
between 45 volts when new to 24 volts at cut-off which is
the end of useful life. The cut-off voltage corresponds to
the left end of the green BAT GOOD area on the meter.
The condition of the battery and the approximate time to
cut-off can be estimated by observing the position of the
meter pointer in the BAT GOOD area.
b. If the set is to be operated from the internal
battery or from an external office battery,
place the AC/BAT switch (located on the side
of the set) to the BAT position, using a small
pointed object; if the set is to be operated
from the ac line, place the AC/BAT switch to
the AC position. For operation from a 24 or
48V office battery, connect a patch cord with
a Western Electric 310 plug to the battery
jack on the side of the case and then connect
the cord to the office battery on the test
board or bay. Inserting the plug disconnects
the internal battery. The office battery is
3-10. The internal battery is of the carbon-zinc type with
its attendant limitations due to temperature. The service
obtained from carbon-zinc batteries depends on factors
such as current drain, discharge temperature, discharge
time and storage prior to use. The battery supplied with
the 3555B should provide in excess of 180 hours of
operation based on a 4 hours/day duty cycle at 77° F (25°
C). At other temperatures this time will change. At
temperatures above 131° F (55° C) the batteries may fail
suddenly while at temperatures below 40° F (-20° C), the
service life will be short.
3-1
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Model 3555B
Section III
Table 3-1. Front, Side and Rear Pane
(1) S and G Jacks: Binding posts accepting banana
plugs, spade lugs, phone tips or bare wires for
connection to the case ground (G) and sleeves (S)
of all INPUT jacks (12) and DIAL/AC MON jacks
(10) and (11).
Controls, Indicators and Connectors either the
NOISE BRDG or the NOISE TERM before the
NOISE WTG filters can be selected.
(9) FUNCTION Switch:
A series of interlocking
pushbutton switches (with the exception of the
HOLD switch which is push-push type) with the
following functions:
(2) Shorting Strap:
A swing-away shorting strap
connecting the S and G terminals together which
may be used to isolate the jack sleeves from case
ground. Not for use with type 347 plugs.
a. VF/Nm
1. HOLD: Applies a dc holding bridge
across the metallic line for the NG, 900
(3) WTG Switch: Selects weighting filters for noise
measurements. These filters are selectable only
when the INPUT switch is in one of the two NOISE
positions. The 3kHz FLAT, C-MSG, 15kHz FLAT
and PROG filters all conform to the standards set
up by the Bell System and Edison Institute for
measuring message circuit noise.
and 600 functions.
The HOLD
pushbutton is the push-push type, ie,
push to make and push to break. The
HOLD
function
cannot
be
accomplished when any one of the
CARRIER pushbuttons is depressed.
(4) RANGE SWITCH: Selects dBm or dBm ranges of
input sensitivity. The RANGE switch markings
correspond to the 0 markings on the meter scale
(6). The black markings are dBm for transmission
measurements and the blue markings are dBrn for
noise measurements.
2. DIAL/BAT:
Connects the multiple
INPUT jacks in parallel with the
DIAL/AC MON jacks for the dial and
talk operation. The circuit is arranged
for loop dialing and the line under test
must supply talk battery. Connects the
meter circuit and a load to the internal
power supply to check the condition of
the battery, ac power or external office
battery as indicated on the green meter
scale. POWER (7) must be ON for the
battery test.
(5) RESPONSE Switch:
Selects NORM meter
response for transmission level measurements or
DAMP for noise measurements where noise is
impulsive in nature.
(6) Meter: A taut band individually calibrated meter
with shaped pole pieces to provide a linear dBm
indication with equal accuracy and resolution over
the entire meter scale. The dBm scale is marked
in black and has 0.1dB resolution for transmission
measurements. The 0 marking at the right end of
the scale corresponds to the black RANGE switch
setting. The dBm scale is marked in blue for noise
measurements. The 0 marking at the left end of
the scale corresponds to the blue RANGE switch
3. NG: Selects the noise-to-ground input
circuits for measuring longitudinal
noise. Attenuation of 40dB is inserted
by this circuit. Earth ground should be
connected to the black G binding post
(1)
4. 900: Selects the input circuitry for
balanced 900 ohm circuits.
This
setting.
The green arc marked BAT GOOD
function selects low frequency
a
corresponds to the green DIAL BAT pushbutton for
checking the power source. The left edge of the
arc corresponds to the battery cut-off voltage of 24
volts and the right edge (meter full-scale)
represents 60 volts which is the maximum voltage
that can be used to power the set without internal
damage.
transformer for voice frequencies.
Response of this transformer is 20Hz
to 20kHz.
5. 600: Selects the input circuitry for
balanced 600 ohm circuits. A low
frequency transformer is selected for
this function.
(7) POWER ON/OFF Switch: turns on all power to the
set. The set operates from either 115 volts or 230
volts ac, the internal 45 volt dry cell battery or from
an external office battery supply.
b. Carrier
1. 600: Selects the input circuitry for
balanced 600 ohm circuits. A high
frequency transformer is selected for
(8) INPUT Switch: Selects TMS, either BRDG or
TERM for transmission measurements and NOISE,
either BRDG or TERM for noise measurements.
For noise measurements the switch must be in
this function.
Response of this
transformer is 1kHz to 600kHz. The
HOLD function is not operative in any
of the carrier functions.
3-3
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Model 3555B
Section III
Table 3-1. Front, Side and Rear Panel Controls, Indicators and Connectors (Cont’d)
2. 135: Selects the input circuitry for 135
ohm balanced circuits. high
providing connection to the input circuitry of the
measuring set. When the DIAL BAT pushbutton is
depressed, the INPUT jacks are connected in
parallel with the DIAL/AC MON jacks.
A
frequency transformer is selected for
this function.
(13) Battery Cover: Removeable by four 1/4 turn screw
fasteners to expose the internal battery for
replacement.
(14) 48V 310: A jack accepting a Western Electric 310
plug with tip negative and sleeve ground to supply
external office battery power to the set. Insertion
of a 310 plug into this jack disconnects the internal
battery. The BAT-AC switch (16) must be set to
BAT for office battery operation.
3. 75: Selects the input circuitry for 75
ohm unbalanced operation. Only the
75 ohm jack can be used for this
function. This function does not utilize
an input transformer, therefore the
maximum bandwidth is available on
this function. This jack accepts a 358
plug.
(10) DIAL/AC MON: A set of multiple jacks accepting
Western Electric type 310 or 347 plugs, 289 dual
plugs and a pair of special clip posts marked T and
R which accept a Western Electric 1011IB
lineman's handset for the dial and talk operation
when the FUNCTION pushbutton marked
DIAL/BAT is depressed. Loop dialing is used and
the circuit must supply talk battery. When any
other FUNCTION pushbutton is depressed, the tip
and ring of these jacks are connected to the AC
MON output of the internal amplifiers for
monitoring purposes.
CAUTION
WHEN OPERATING FROM AN EXTERNAL
BATTERY, CORD SHOULD BE CONNECTED
TO MEASURING SET FIRST, THEN PLUG
INTO BATTERY SUPPLY TO AVOID
SHORTING THE OFFICE BATTERY.
(15) 0.15A-SPARE Fuse: A 0.15A slo-blo fuse and a
spare for measuring set protection when operating
from AC power. Fuses are not used when the set
is battery powered.
(16) BAT-AC Switch: A slide switch for selecting the ac
power source or the internal battery and office
battery jack, (14), power source. The switch may
be operated by a small screwdriver or pointed tool
inserted into the slot in the switch.
(11) DC MON: Accepts a Western Electric 310 or 347
plug for tip negative and sleeve connections to an
external dc recorder.
Output voltage is
proportional to the input voltage on any one setting
of the RANGE switch.
(17) AC Power Receptacle: A 3 prong power receptacle
for the special power cord stored inside the front
(12) INPUT: A set of multiple jacks accepting Western
Electric 241 (or 289), 309, 310 and 358 plugs and a
pair of binding posts marked T and R for banana
plugs, spade lugs, phone tips or bare wires
cover.
The BAT-AC switch (16), must be
positioned to AC for this power source.
3-11. High storage temperature is damaging to dry
cells and tends to reduce shelf life. Low storage
temperature is beneficial to battery life although the
battery should be warmed to room temperature prior to
the arc on the meter face, replace the
battery.
3-12. LEVEL AND NOISE MEASUREMENTS.
use.
Turning off the set when not in use and
consideration of the above factors will maximize battery
life. The instant turn characteristics of this set with no
warm-up time required allows turning off between
measurements.
3-13. Since the 3555B is both a level measuring set
and a noise measuring set, the procedure for making
these measurements will be treated separately. Level
measurements can be made at voice frequencies and
carrier frequencies. Since the procedure for making
voice and Carrier level measurements are identical
except for the FUNCTION pushbutton utilized, only one
procedure will be described in detail.
NOTE
If the battery voltage indication drops below
the left end of the arc on the meter face the
set will not operate properly. This will be
noted by a slow oscillation of the meter. If
this symptom is encountered, depress the
DIAL/BAT pushbutton and check the battery
condition. If the indication is to the left of
3-14. LEVEL MEASUREMENTS.
3-15. The 3555B can be used as a wide range and
wide
3-5
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Section III
Model 3555B
frequency Transmission Measuring Set (TMS) for voice, lineman's hand set which was used for the dialing
program and carrier multiplex measurements. The set will operation can be used for monitering by leaving it
operate over a wide range of environmental conditions and connected to the clip posts. The jacks marked 310 will
maintain a high degree of accuracy.
accept a head phone or recorder connected to the tip and
3-16. In general, transmission level measurements are ring of a 310 plug or tip and sleeve of a 347 plug. The
made by connecting the circuit under test to the INPUT performance of the set is not affected by this output and
jacks with a suitable patch cord, selecting the proper any impedance head-phone may be used.
bridging or terminate condition and impedance, and then 3-21. The DIAL/BAT function also checks the power
operating the RANGE switch to provide an on-scale meter source used. The green arc on the meter marked BAT
indication. Transmission level measurements are made GOOD corresponding to the green BAT marking on the
with the INPUT switch in TMS position either bridging or pushbutton, indicates the range of voltages for proper
terminated. In this position, the set has its maximum operation. Full scale corresponds to 60 volts and the left
frequency range.
end of the arc corresponds to the battery cut-off voltage of
3-17. The multiple INPUT jacks and binding posts 24 volts. Thus the remaining battery life can be estimated
accept the Western Electric 309, 310 and 358 single plugs by noting the position of the pointer in the green arc.
and the 241 or 289 twin plug. The two red binding posts Since the set POWER must be turned ON to perform this
marked T (tip) and R (ring) will accept banana plugs, check, the battery is properly loaded to give a true
spade lugs, phone tips or bare wires. These jacks and indication of its condition. When operating from the
binding posts are all connected in parallel and only one external office battery or AC power, the meter monitors
should be used at a time. A patching cord such as the this voltage to indicate if it is the correct level to properly
Western Electric 3P12H, consisting of a cord with a 310 power the set. The POWER switch turns OFF and ON all
plug on one end and a 309 plug on the other end, should power to the set.
be kept with the instrument as a universal patch cord. The 3-22. The remaining FUNCTIONS are used to set up the
75 ohm jack accepts Western Electric type 358 plugs for input conditions. The Ng function will be discussed under
75 ohms. unbalanced carrier measurements.
the paragraph heading, "NOISE MEASUREMENTS". The
3-18. The sleeves of all the INPUT and DIAL jacks are impedance of the set is selected by the pushbuttons
connected together and to the black binding post marked marked 900 and 600 for voice frequencies and 600, 135
S. The binding post in turn, is connected through a swing- and 75 for carrier frequencies. The 900 and 600 ohm
away shorting strap to a second black binding post marked impedances are normally used for loop plant testing while
G. This binding post is the measuring set case ground. 600, 135 and 75 ohms are usually reserved for carrier
When it is necessary to establish a battery or ground system measurements. A bridged or terminated condition
connection on the sleeve for PBX test purposes, this is determined by the position of the INPUT switch. Using
shorting strap may be disconnected by loosening the black this procedure, the meter will always indicate in dBm for
binding posts and swinging away the strap. A cord is then the impedance selected, bridging or terminated. The
connected to the S terminal and may be connected to the terminations, when used, are provided with a dc blocking
battery or ground for the test. Type 347 plugs must not be capacitor. Accidental application of carrier or telegraph
used when the shorting strap is removed.
battery, office battery or ringing voltage will not damage
3-19. The multiple jacks marked DIAL/AC MON are the set. The pushbutton marked HOLD bypasses the
connected in parallel and accept a 310 or a 347 single plug INPUT switch and terminates the circuit in addition to
or a 289 dual plug. A dial with the impulse springs placing the holding bridge across the line that is connected
connected to the tip and ring of a 310 or 347 plug may be to the INPUT. When the INPUT switch is in either of the
used or a lineman's handset such as the Western Electric NOISE positions, weighting filters can be selected by the
1011 B may be connected to the two square clip posts for NOISE WTG switch for noise measurements.
the dialing and talk operation. When the FUNCTION 3-23. The RANGE switch selects the dBm range of the
pushbutton marked DIAL/BAT is depressed, the DIAL meter. To avoid overloading the set, turn the RANGE
jacks are connected to the INPUT jacks and a number may switch to +30dBm when connecting a circuit for testing.
be dialed on the line connected to the INPUT jacks. The Once the circuit connection is established turn the RANGE
circuit is arranged for loop dial operation and the circuit switch counterclockwise until an on-scale indication is
under test must supply talk battery.
obtained. The black dBm marking on the RANGE switch
3-20. Once the switching equipment has been seized by identifies the input level required to deflect the meter to
the dialing operation, the connection can be held by the 0 mark on the black scale. The meter uses shaped
depressing the HOLD pushbutton. This places a dc bridge pole pieces to present linear dBm markings on the scale
consisting of a high impedance retardation coil, across the with marks at 0.1 dBm increments. The accuracy and
INPUT terminals. This coil has negligible effect on resolution of this type of meter is the same at any point on
measurements of voice frequencies. Once any other the scale and it is not necessary to keep the pointer in the
pushbutton is depressed, the AC output of the internal upper portion of the scale for maximum accuracy. The
amplifier circuit is returned to the DIAL/AC MON jacks for accuracy of the set is not affected by the position of the
an external head Model 3555B phone which can be used set. This type of meter will have the pointer off-scale to
to monitor the noise or tones being measured. The the
left
3-6
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Model 3555B
Section III
when no input signal is present and a mechanical zero indicated on the recorder will be the algebraic sum of the
adjust is not required. The actual input level to the set is RANGE.
the algebraic sum of the black dBm meter scale and black
RANGE setting. For example, RANGE is set to 40dBm
and the meter indicates -6.3dBm. The input level is then (-
40) + (-6.3) = -46.3dBm. If the RANGE switch is at
+20dBm and the meter indication is 4.7dBm, the level is
(+20) + (4.7) = +15.3dBm.
3-24. All panel markings corresponding to the proper
dBm markings on the RANGE switch and meter face are in
black, as is the TMS position of the INPUT switch. The
blue markings correspond to the settings for noise
response of the meter rectifier circuit is RMS which allows
the set to measure the true power of any arbitrary input
waveform provided the crest factor does not exceed 4:1.
Crest factor is defined as the ratio of the peak value of the
waveform to the RMS value of that waveform. In most
telephonic measurements, consideration of this crest
factor is not necessary.
3-25. The balanced input to the set is achieved through
the use of two repeat coils, one for voice frequencies from
20Hz to 20kHz and the other for carrier frequencies from
10kHz to 600kHz. The maximum high frequency range is
achieved through the use of the 75 ohm functions and the
75 ohm jack. This input bypasses both input repeat coils,
thus allowing measurements from 30Hz to 3MHz. This
high frequency range is limited to 600kHz on the +20 and
+30dBm ranges. The maximum longitudinal input voltage
is 150 volts peak between tip and ring and 200 volts rms at
60Hz between either tip or ring and ground.
3-28. NOISE MEASUREMENT.
3-29. One of the primary functions of this set is to
measure message circuit noise, both metallic and noise-to-
ground. The weighting filters built into this set are switch
selected and their characteristics conform to the standards
set up by the Bell System and Edison Electric Institute.
3-30. In general, noise-metallic measurements are made
by connecting the circuit under test to the INPUT jacks
with a suitable patch cord, selecting the proper bridging or
terminate condition and impedance, selecting the proper
weighting filter and operating the RANGE switch to provide
an on-scale meter indication.
Noise measurements
involve many of the same operations as the level
differences will be discussed.
3-31. Four filters are supplied for noise measurements;
C-MESSAGE and 3kHz FLAT for message circuit noise
measurement, a PROG and 15kHz FLAT for broadcast
studio-transmitter links and telephone company program
circuits.
These filters are necessary to allow the
measuring set to approximate the response of the human
ear and give an indication representative of a person's
subjectiveness to noise. The frequency response of these
3-32. Once a circuit has been connected, the RANGE
switch is adjusted until the noise fluctuations appear on-
scale on the meter with normal response, and a two-to-
three minute observation of the pointer fluctuations is
made to establish the point at which the pointer appears
most of the time, disregarding the occasional high peaks.
For rapidly fluctuating noise such as atmospheric static or
switching noise, operate the RESPONSE switch to DAMP.
In this position of the switch, the level of the most
frequently occurring peaks should be read. Noise is
specified in dBm (decibels above reference noise) and the
type of filter used is noted, for example, dBmC meaning
C-message weighting is used.
3-33. The noise-metallic level is the algebraic sum of
the indication on the blue dBm meter scale and the blue
dBm RANGE switch setting. For example, RANGE is set
to 20dBm and the meter indicates +7dBm. The noise-
metallic level is (20) + (+7) = +27dBm. The RANGE
switch marking indicates the level at the 0dBm mark on
the left end of the meter scale.
3-34. Occasionally other message circuit weightings
such as the older Bell System F1A weighting or the
International Telecommunication Union's CCITT or
psophometric weighting may be required. To convert from
C-message to F1A, subtract 6dBm from the C-message
indication. The units for F1A weighting are dBa, meaning
decibels adjusted. To convert from C-message to CCITT
or psophometric weighting, subtract 1dBm from the C-
message level as read on the black dBm meter scale and
RANGE switch setting. This will give the noise level in
dBm which is acceptable for psophometric measurements.
3-26. The switch marked RESPONSE determines the
speed of the meter response and is usually left in the
NORM position for transmission measurements.
3-27. The jack marked DC MON accepts a Western
Electric 310 or 347 plug with connections to the tip and
sleeve. The dc voltage supplied by this jack can be used
to operate a dc potentiometric recorder requiring 1V or a
dc galvanometric recorder requiring 500uA. The dc output
is proportional to input level on any one range and not
meter deflection since the meter is logarithmically scaled.
Knowing the current required to drive the recorder full
scale and the input impedance of the recorder, enter these
determine if the recorder is suitable for use with this set. If
these numbers do not fall within the compatability area,
set and adjust the RANGE switch until a near full scale
indication is observed on the meter. Connect the recorder
plug with the tip negative to the DC MON jack and adjust
the input level until the meter indicates 0dBm. Mark this
point, which should be near full scale, on the recorder
paper. Decrease the input level until the meter indicates -
1dBm. Mark this point on the recorder paper. Continue
until the recorder has been calibrated for each major dBm
division on the meter. The actual input level to the set as
3-7
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Section III
Model 3555B
3-40. Crosstalk measurements involve low level
measurements and part of the meter indication may be 3-
8 Model 3555B caused by noise in addition to crosstalk.
The general technique is to measure with crosstalk and
3-35. As an aid in identifying the source of noise, the
DIAL/AC MON jacks can be used with a monitoring
receiver to listen to the noise which will have
approximately the same quality as that heard by a
subscriber. Particular types of noise like power line
induction, switching noise, atmospheric static, crosstalk or
random noise may be identified by this listening test. To
aid in bringing up the level of the lower frequency power
line noise, the 3kHz flat weighting is used. A substantial
increase in meter indication with the 3kHz flat weighting
indicates the presence of low frequency noise and it will
also sound louder in the monitoring headphone.
3-36. In some cases recording of the noise during a
busy period is necessary. The recorder connections and
should be done using the dBm scale rather than the dBm
scale and it should be noted that the RESPONSE switch
also damps the recorder.
3-37. Noise-to-ground measurements are made by a
special input circuit arrangement which is used when
either the Ng or Ng HOLD pushbutton is depressed. Dial
and talk may be accomplished on the metallic circuit and
the metallic connection held by using the Ng HOLD
pushbutton. It is necessary to establish a good earth or
system ground and connect it to the black binding post
marked G. The noise-to-ground measurement is 40dB
less sensitive than the noise metallic measurement
because of the voltage divider in the input circuit. This
requires adding 40dB to the meter indication to arrive at
noise present and then measure noise alone.
A
correction factor must then be applied and can be found
3-41. RECORDER COMPATIBILITY.
3-42. If an external recorder is to be used to monitor the
dc output of the 3555B, the Recorder Compatibility graph,
particular recorder can be used. Recorders with input
characteristics that fall below the compatibility area can
be used provided a suitable resistor is used between the
3555B dc output and the recorder input.
3-43. To choose the value of this resistance, simply
follow the line designating the full scale current of your
recorder, horizontally until it intersects the top line in the
Recorder Compatibility graph. From this intersection
follow the vertical line to find the total impedance RT
input impedance of the recorder should be subtracted
from this value RT to determine the value of R1. For
example, assume that your particular recorder has an
input impedance of 2000 ohms with a full scale sensitivity
of 20uA. Follow the 20uA line to the right until it
intersects the top line at 48 kilohms. The value of R1 will
then be 48 kilohms -2 kilohms input impedance = 46
kilohms.
the correct noise-to-ground level.
The level is the
3-44. Recorders with input characteristics that fall
to monitor the 3555B dc output since full scale deflection
of the recorder cannot be accomplished by the 3555B.
algebraic sum of the blue RANGE switch setting and the
blue meter scale indication plus 40dB. For example,
RANGE is set to 20dBm and the meter indicates +3dBm.
The noise-to-ground level is 20 + (+3) +40= 63dBm.
Some telephone company operating procedures disregard
the 40dB correction factor in which case the noise-to-
ground level would be 20 + 3 = 23dBm.
3-38. The Nm and Ng indications can be used to
compute the balance of a facility since balance is defined
as the degree of rejection of longitudinal signals. The
degree of balance in dB where the major part of noise-
metallic is due to noise-to-ground, is given by the
equation, Balance in dB = Nm - Ng. For example, if the
noise-metallic level of a circuit is +26dBm and the noise-
to-ground of the same circuit is +9OdBmC, the balance in
dB is (+26) - (+90) = 64dB. In the case mentioned above
where the 40dB correction factor is neglected, the balance
in dB = (Nm) (Ng + 40).
Figure 3-3. Impedance Matching 3555B to Recorder
3-45. APPLICATIONS.
3-46. Sometimes it is necessary to transmit or send a
tone on a line and then measure the received signal
coming back on the same line. Rather than change
connections back and forth between the 3555B and 236A
Oscillator when changing from SEND to RECEIVE and
thus take a chance on dropping the line, it is much more
convenient to make one set of connections and then
select SEND or RECEIVE by means or a switch. Refer to
send and receive can be accomplished with a minimum
number of operations. To dial, set both function switches
to DIAL and dial the desired line on the butt-in. To send,
change the
3-39. Other general purpose uses of the 3555B are
volume and crosstalk measurements.
characteristics of the set make it approximately correct for
VU measurements. The RANGE switch should be
The ballistic
adjusted until the meter pointer fluctuations are on-scale
and should be observed for the maximum of the
frequently occurring peaks, disregarding the occasional
high peaks. The meter indication in dBm is equal to VU
(volume units.)
3-8
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Section III
Model 3555B
236A FUNCTION switch to 600 HOLD or 900 HOLD,
depending on the impedance required. To receive a
tone, set the 3555B FUNCTION switch to either 600
HOLD or 900 HOLD (whichever is appropriate) and
change the 236A FUNCTION switch to DIAL. To send
again, simply change the 236A to 600 HOLD or 900
HOLD. If holding is not required or dialing is not
required, simply select the impedance and switch back
and forth on the 236A FUNCTION switch.
3-53. CROSSTALK MEASUREMENTS.
3-54. Crosstalk is interference on a transmission line
caused by inductive and capacitive coupling between
pairs of transmission lines in close proximity. Crosstalk
can be classified as near-end and far-end. Far-end
crosstalk is interference at the end of the transmission
line opposite the , signal source while near-end crosstalk
is interference detected at the same end of the line as
the signal source.
3-48. TRANSMISSION LOSS MEASUREMENTS.
3-49. Transmission loss is defined as the ratio of
power from a transmission line by a receiving terminal
to the power available from the sending equipment and
is dependent on three factors; power dissipated by the
dc resistance of the line, power losses because of
impedance mismatch, power transferred to other circuits
3-50. These factors are difficult to measure
separately. Their sum, however, is relatively easy to
measure with the -hp- 236A/3555B combination.
measurement setup. The oscillator is adjusted for a
reference level and the signal is measured at the other
end of the line with a level meter. Loss measurements
are usually made at various frequencies to determine
the response of the line.
3-52. Ideally the man at each end of the line will have
both an oscillator and a Transmission Measuring Set
(TMS) so that the loss can be measured in both
directions, If the line that is being tested passes through
central office switching equipment, the oscillator or TMS
at the remote end is placed in the DIAL mode and the
lineman's handset connected to the DIAL posts,
permitting the repairman to bypass the instrument
circuitry and dial his test board at the central office.
Tests are then made in the 600 or 900 ohm HOLD
positions, which provide a dc path to hold the switching
relays.
Table 3-2. Crosstalk Correction Factor
dB Correction Factor
(Crosstalk + Noise) in dB
Minus Noise Alone in dB
Crosstalk in dB =
(Crosstalk + Noise)
Minus Correction Factor
1
2
3
7
4
3
2
1
0
4 to5
6 to 8
9 and above
3-55. Since different frequency bands are used for
each direction of transmission on two wire carrier
systems, near-end crosstalk cannot be detected. The
situation is quite different, however, for far-end crosstalk
since it is in the same frequency band as the desired
signal and can be detected.
A-B and the other designated C-D with A and C
representing the near-end of one of the pairs, and band
D representing the far-end of the other pair. First
measure the transmission loss between A and B. Then
measure the transmission loss from A to D. The
crosstalk coupling loss in dBx is the difference in the
reading from A to B and the reading from Ato D.
3-57. IDENTIFYING NOISE CHARACTERISTICS.
Figure 3-6. Typical Test Setup for Measuring Insertion Loss
3-10
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Model 3555B
Section III
Figure 3-7. Test Setup for Measuring Crosstalk Coupling Loss
3-58. Normally, a frequency selective voltmeter is
used to identify the characteristics of transmission line
interference in order to trace it down to its origin and
apply the appropriate corrective action. As an expedient
for troubleshooting, there are several subjective
measurements that the 236A/3555B can make to help
identify the interference characteristics.
oscillator frequency dial to an accuracy of approximately
±3%. In practice, this measurement would probably be
made using a "loop around" technique. The oscillator
would be connected to a quiet line at the remote location
and this line would be tied to the noisy line back at the
central office. This permits one man to operate both the
oscillator and the test meter.
3-59. Since power line noise is the most common
nuisance, a quick check with the 3555B should be made
first. By noting the difference in noise readings between
the 3kHz FLAT and C-message weighted modes, an
indication of line frequency disturbance can be
ascertained if the 3kHz flat mode shows a substantially
higher reading.
3-60. As a further aid in identifying noise, the
lineman's handset can be connected to the AC
MONITOR terminals and an aural analysis made.
Although the handset will not respond to 60Hz, line
interference is usually very rich in odd harmonics and
180Hz can easily be identified. This test also helps to
identify "babble" and other audio frequency interference.
3-61. Vagrant noise, such as atmospheric noise, can
be analyzed by connecting a strip chart recorder to the
DC MONITOR terminals. Long-term seasonal and
temperature effects can also be measured very
conveniently with a recorder.
3-62. Frequency of strong interfering periodic signals,
such as radio transmitters, can be roughly determined
with the 236A and 3555B. The 236A is connected to
one end of the line and the 3555B to the remote end, as
with transmission loss measurements. The oscillator
output is increased until the test meter barely indicates a
signal above the noise. The oscillator frequency is then
changed very slowly while the repairman observes the
3555B for a beat. By tuning for a beat, the frequency of
the interfering signal can be read directly off the
3-63. When a current flows through a conductor, it
sets up two distinct fields around the conductor - - the
electrostatic (capacitive) field and the magnetic
(inductive) field.
Both are capable of inducing
longitudinal voltages in adjacent conductors, and both
increase in proportion to the power and frequency of the
current from which they result. They differ greatly,
however, in how they affect nearby circuits. The voltage
resulting from magnetic induction varies inversely-with
the impedance of the line. That is, the higher the line
impedance, the less voltage that can be induced by a
magnetic field. Capacitively coupled voltage, on the
other hand, increases in direct proportion to line
impedance-- the higher the impedance, the greater the
capacitive coupling. By means of a simple test, it is
possible to identify the coupling between two lines, as
inversely proportional to line impedance, the voltage
increase as the impedance is lowered (i.e., shorted).
Conversely, since capacitively coupled voltages are
directly proportional to impedance, the coupled voltage
should be performed to correlate the result.
3-64. MEASUREMENTS IN DBC.
3-65. The term dBC means dB Collins and is defined
as
3-11
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Section III
Model 3555B
Figure 3-8. Simple Test for Inductive and Capacitive Coupling
0dBC = 0.775V across any impedance as read on an
-hp- Model 400D AC Vacuum Tube Voltmeter. Thus,
the dBC is strictly a relative term.
3-70. The 3555B comes equipped with all the
necessary parts for converting the 135 BAL function to a
150 BAL function.
The following is a simplified
3-66. Measurements can easily be made in dBC. by
utilizing the Model 3555B Telephone Test Meter. To
make these measurements, set FUNCTION to 600 and
the INPUT switch to TMS BRDG. Any termination
required other than 600 ohms must be provided
externally and connected across the two binding posts T
and R. Termination can also be made using a patch
cord and any one of the other INPUT jacks since all
INPUT jacks are connected in parallel. If a 600 ohm
termination is to be used, the internal termination can be
utilized by placing the INPUT switch to the TMS TERM
position.
procedure for making the modification.
a. Remove the set from the case and remove
the FUNCTION board. Clip the shorting
and reinstall the FUNCTION board. Leave
the set out of the case.
b. Set the 3555B controls as follows:
RANGE..........................................0dBm
FUNCTION................................135 BAL
INPUT ..................................TMS TERM
c. Remove the 150 BAL decal from the
envelope supplied with the set. Remove
the backing from the decal and place it
over the 135 BAL function pushbutton.
d. Connect a 150 ohm balanced source to the
input of the 3555B at a level of 0dBm
(387mV rms) at a frequency of 1kHz. Turn
e. Reinstall the set in its case.
3-67. MEASUREMENT PROCEDURES.
procedures for measuring levels and noise balance,
recorder calibration and transmission loss using the
3555B. For a more detailed discussion on level and
3-69. 150 BAL CONVERSION.
3-12
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Model 3555B
Section III
Table 3-4. Noise Metallic Measurements
Table 3-3. Level Measurement
STEP
PROCEDURE
STEP
PROCEDURE
1.
Turn the 3555B/ON and depress the
DIAL/BAT pushbutton. The meter should
indicate in the green BAT GOOD area. If it
does not, replace the battery or check the
power source before attempting to make any
measurements. The battery test operates for
internal battery, office battery or ac power
source.
Select either TMS BRDG or TMS TERM,
depending on the measurement being made.
The weighting filters are not in the circuit at
this time.
1.
Turn the POWER switch to ON and depress
the DIAL/BAT pushbutton. The meter should
indicate in the green BAT GOOD area. If it
does not replace the battery or check the
power source. The battery test operates on
internal battery, office battery or ac power
source.
Select either NOISE TERM or NOISE BRDG,
depending on the measurement being made.
Select the impedance to match the circuit to
be tested using the FUNCTION pushbuttons.
The 900 BAL VF/Nm pushbuttons only should
be used for noise metallic measurements in
the frequency range of 20Hz to 20kHz. The
HOLD function can be used in NOISE TERM
if desired.
Select the appropriate weighting filters using
the NOISE WTG switch.
Set the RANGE switch to 110dBrn.
Connect the set to the circuit to be tested
using a suitable patch cord and down range
for an on-scale indication.
Observe the meter fluctuations for two or
three minutes and take a reading where the
meter pointer appears to be most of the time,
disregarding any occasional peaks.
2.
3.
2.
3.
Select
the
impedance
(FUNCTION
pushbutton) to match the circuit to be tested.
Select either 900 BAL or 600 BAL (VF/Nm) for
frequencies between 20Hz and 20kHz. Select
600 BAL or 135 BAL (CARRIER) for balanced
measurements between 1 kHz and 600kHz.
Select 75 UNBAL for 75 ohm unbalanced
measurements between 30Hz and 3MHz.
Set the RANGE switch to +30dBm. Set the
RESPONSE switch to DAMP.
Connect the set to the line using a suitable
patch cord. For balanced measurements use
a cord having a 309 or 310 single plug, a 241
dual plug or banana plugs, bare wires or clip
leads. For unbalanced carrier measurements
(75 ohm only) use a cord having a 358 plug.
4.
5.
6.
4.
5.
7.
NOTE
For rapidly fluctuating noises
such as atmospheric noise or
switching noise, operate the
RESPONSE switch to DAMP
and read the level of the most
frequently occurring peaks.
NOTE
Carrier measurements are
limited to the -50dBm RANGE
thru the +10dBm RANGE.
6.
Down range the RANGE switch for an on-
scale indication.
algebraic sum of the black RANGE setting
plus the black meter scale indication.
Level is equal to the
8.
Noise level is equal to the sum of the blue
RANGE switch setting in dBrn and the
indication on the blue meter scale in dBrn.
EXAMPLES:
EXAMPLE:
RANGE = -50dBm
RANGE
METER
NOISE LEVEL = +45dBrn
=
=
40dBrn
+5dBrn
METER =
LEVEL =
+1dBm
-49dBm
RANGE = +20dBm
METER =
LEVEL =
-4dBm
+16dBm
3-13
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Section III
Table 3-5. Noise-to-Ground Measurements
Model 3555B
Table 3-6. Balance Measurement
STEP
PROCEDURE
STEP
1.
PROCEDURE
1.
Turn the 3555B POWER switch to ON and
depress the DIAL/BAT pushbutton. The meter
should indicate in the green BAT GOOD area.
If it does not replace the battery or check the
power source. The battery test operates for
internal battery, office battery or ac power
source.
Perform the Noise-to-ground measurement as
Perform the Noise Metallic measurements as
Compute the line balance in dB using the
results of the above checks.
2.
3.
2.
3.
Set the INPUT switch to NOISE BRDG.
Select the appropriate weighting filter using
the NOISE WTG switch.
Balance (dB) = Nm - NG
EXAMPLE:
4.
5.
Set the RANGE switch to 110dBrn.
Depress the NG pushbutton and connect the
set to the circuit to be tested. Down range for
an on-scale indication.
Noise-to-ground =
+26dBrn
= (-)+90dBrn
-64dBm
Noise Metallic
Balance in dB
=
NOTE
Dial and talk may be
accomplished on the metallic
circuit and the connection
held by depressing the HOLD
pushbutton.
NOTE
noise-to-ground
measurement above includes
the 40dB correction factor.
The
Table 3-8. Transmission Loss Measurement
Table 3-7. Recorder Calibration
STEP
PROCEDURE
STEP
PROCEDURE
1.
For a transmission loss measurement to be
meaningful, it should first be determined if
there are any extraneous signals present that
will affect your measurement. To do this,
connect the measuring set to the circuit and
determine if interfering signals are present.
Levels below 60dB can, in most cases, be
ignored. A butt-in can be connected to the AC
MON jacks to aid in determining the
interfering source.
Establish a connection like the ones shown in
Adjust the oscillator output level for 0dBm.
Measure the level at the receiving end and
record this level.
1.
Determine the input impedance and full scale
sensitivity of your recorder and refer to
your recorder is suitable for use with this set.
The dc voltage supplied by the DC MON 310
jack will drive a dc potentiometric recorder
requiring 1V or a dc galvanometric recorder
requiring 500uA.
Connect an input voltage to the set and adjust
the RANGE switch until a near full-scale
indication is observed on the meter.
Connect the recorder plug with the tip
negative, to the DC MON jack and adjust the
input level until the meter indicates 0dBm.
Mark this point on the recorder paper which
should be near full scale.
Decrease the input level to the set until the'
meter indicates -1dBm. Mark this point on the
recorder paper. Continue this procedure until
every major dBm division on the meter has
been calibrated on the recorder paper.
The actual level to the set as indicated on the
recorder is equal to the algebraic sum of the
RANGE setting and recorder indication.
2.
3.
2.
3.
4.
Insertion loss is equal to the difference
between the sending level and the receiving
level, ignoring any extraneous signals.
4.
5.
EXAMPLE:
Sending level
Receiving level = (-)- 20dBm
Insertion loss 20dB
=
0dBm
=
3-14
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Model 3555B
Section IV
SECTION IV
THEORY OF OPERATION
Set. Refer to this figure for the following block diagram
description.
4-1.
4-2.
INTRODUCTION.
The Model 3555B Transmission and Noise
4-9.
The input signal is first applied to the
Measuring Set is a special measuring set designed for
uses in testing telecommunications equipment. Inputs
between -90dBm and +30dBm full scale can be selected
in twelve ranges for level measurements and
correspond to the black markings on the meter scale
and the RANGE switch. Noise measurements between
0dBrn and +120dBrn full scale can be made, selectable
in twelve ranges and corresponds to the blue markings
FUNCTION switch where the input circuitry is set up to
accommodate the type of measurement being made.
For voice frequencies, impedances of 900 ohms or 600
ohms can be selected, bridged or terminated. Voice
frequencies are then applied to a transformer with a
frequency range of 20Hz to 20kHz. The HOLD function
places a high inductance bridge across the INPUT
terminals to simulate an off-hook condition. For carrier
frequencies impedances of 600 ohms, and 135 ohms
can be selected, terminated or bridged, balanced or
unbalanced. Carrier frequencies at these impedances
are applied to a transformer having a frequency range
from 5kHz to 600kHz. For 75 ohm carrier frequencies
an unbalanced input is provided. This input can be
either terminated or bridged. HOLD is not possible on
any of the carrier functions.
4-10. For longitudinal measurements, an Ng function
is provided which places a 40dB attenuator across the
INPUT terminals. The HOLD function bridges the input
with a holding coil while measurements are being made.
The output of the 40dB attenuator is always applied to
the voice frequency transformer.
4-11. The DIAL/BAT function serves two functions.
First it connects the DIAL/AC MON jacks to the INPUT
jacks so that a handset can be used for dialing.
Secondly, the meter is connected to the unregulated
power supply so that the battery condition can be
monitored.
on the meter scale and RANGE switch.
When
measuring rapidly fluctuating noises, a damping circuit
can be inserted by the RESPONSE switch.
4-3.
Impedances of 75, 135 and 600 ohms,
terminated or bridging can be selected for carrier level
measurements. The 135 and 600 ohm functions can be
either balanced or unbalanced while the 75 ohm
function is unbalanced only. For voice frequencies,
impedances of 600 and 900 ohms are provided. These
impedances are selectable by the pushbutton
FUNCTION switch and can be terminated or bridging,
balanced or unbalanced.
4-4.
A noise-to-ground (Ng) function is included to
permit measurement of longitudinal noise. When the
Ng pushbutton is depressed, a 40dB attenuator is placed
across the INPUT terminals.
4-5.
The HOLD function places a high inductance
holding coil across the INPUT terminals to simulate an
off-hook condition while measurements are being made.
The HOLD function is not operative on any of the carrier
functions.
4-12.After the signal is conditioned by the input circuitry
it is coupled to the RANGE attenuator where the signal
level is adjusted to provide the proper input for the Input
Amplifier. The RANGE attenuator provides from 0dB to
80dB of attenuation. It also provides gain switching for
the Input Amplifier.
4-6.
A variety of INPUT and DIAL jacks are provided
which accept Western Electric type 241 and 289 dual
plugs, 309, 310, 347, and 358 single plugs, dual banana
plugs, clip leads and bare wires.
4-7.
4-8.
BLOCK DIAGRAM DESCRIPTION.
of the Model 3555B Transmission and Noise Measuring
Figure 4-1. Simplified Block Diagram
4-1
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Section IV
Model 3555B
4-13. The output of the Input Amplifier goes to the
INPUT switch where noise filters are set up for selection
by the NOISE WTG switch. In the NOISE position,
either 3kHz FLAT weighting, C Message weighting,
15kHz FLAT weighting or PROGRAM weighting can be
selected by the NOISE WTG switch. In the TMS
position of the INPUT switch the filters are bypassed for
transmission level measurements.
switch is in the TERM position. A bridging
HOLD is not possible. The TERM switch
connects the two windings of L1 in series.
pushbutton serves two purposes. First it
disconnects the meter from the detector
and connects it to the unregulated power
supply so that the battery voltage can be
monitored. Secondly, the DIAL/AC MON
jacks are disconnected from the amplifier
ac output and connected to the INPUT
4-14. The output from the INPUT switch goes to the
meter amplifier. This amplifier provides an ac signal to
the DIAL/AC MON jacks so that a handset can be used
to listen to the signal being measured.
This is
jacks.
This permits connecting the
particularly useful in determining noise characters.
4-15. The detector circuit provides an equivalent rms
detected voltage to drive the meter. The meter has
shaped pole pieces to provide a linear meter scale both
for dBm and dBrn.
lineman's handset to the balanced line for
the purpose of dialing.
connects a 40dB attenuator across the
balanced input terminals for longitudinal
measurements. This attenuator consists of
A1R5 thru A1R8 and A1C1. The output is
taken from the junction of AIC1 and A1R8.
This output is referenced to ground and
applied to the voice frequency transformer
A1T2.
d. 900 (Vf/Nm): The 900 function switch S4
selects terminating resistors AIRI and A1R9
for 900 ohm terminations. The INPUT
switch must be in _ the TERM position to
complete the circuit for this termination.
The 900 function switch also places a
ground on the 900 ohm relay A3K1 which
provides gain switching in the Input
Amplifier so that the meter will indicate in
dBm. The 900 ohm signal is applied to the
voice frequency transformer A1T2. HOLD
can be accomplished on this function.
4-16. DETAILED CIRCUIT DESCRIPTION.
4-17. The purpose of the function switch is to set up
the input conditions to match the type of measurement
being made. Impedances can be selected to match the
lines to be tested and can be either bridged or
terminated. Separate transformers are selected for
voice frequency and carrier frequency measurements.
A 40dB attenuator is bridged across the input terminals
for longitudinal noise measurements when the Ng
pushbutton is depressed. The HOLD function places a
high inductance holding coil across the input terminals
to simulate an off-hook condition. Each of these
functions is described in detail in the following
paragraphs.
a. HOLD: When the HOLD pushbutton is
depressed a high inductance coil LI is
connected across the Model 3555B
balanced INPUT terminals if the INPUT
Figure 4-2. Simplified DIAL BAT Function
4-2
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Model 3555B
Section IV
Figure 4-3. Simplified NG Function
e. 600 (Vf/Nm): The 600 function switch S5
attenuator is composed of four L pads, selectable in
combinations to provide from 0dB to 80dB of
attenuation. Two 30dB pads are selected by A2S1A and
A2S1B, a 20dB pad is selected by A2S1C and a 10dB
pad is selected by A2S1D. Another section of the
RANGE attenuator switch provides gain switching for
the Input Amplifier in the -80dBm, -70dBm and -60dBm
selects terminating resistors A1R2 and
A1R10 for a 600 ohm termination. The
INPUT switch completes the circuit for this
termination. The 600 (Vf/Nm) signal is
applied to T2.
No gain switching is
performed in this function since the set is
normalized at 600 ohms HOLD can be
accomplished on this function.
600 (Carrier): This function is identical to
the 600 (Vf/Nm) function except that the
signal is applied to A1T1 and HOLD cannot
be accomplished on this function.
information on range attenuation and amplifier gain.
4-20. INPUT AMPLIFIER A3. (Schematic No. 2)
4-21. The purpose of the Input Amplifier is to provide
the necessary gain at each setting of the RANGE switch
and to provide the necessary gain at all impedances.
This amplifier is normalized at 600 ohms and the
following discussion is for the 600 ohm function.
4-22. Diodes A3CR1 thru A3CR4 serve as protection
for the input amplifier. Signals greater than 7 volts
peak-to-peak will be conducted to ground through these
diodes. The gain of this amplifier is determined by the
negative feedback from the emitter of A3Q5 to the base
of A3Q2. This feedback is first determined by the ratio
of A3R13 to the sum of A3R14 and A3R15. In position
1 of the RANGE switch (-80DBM) this feedback is
further divided by the ratio of A3R11 to the sum of
A3R25 and A3R26. In position 2 (-70DBM) of the
RANGE switch the feedback is determined by the ratio
of A3R11 to the sum of A2R13, A3R25 and A3R26. In
position 3 (-60DBM) of the switch the feedback is
determined by the ratio of A3Rll to the sum of A2R13,
A2R14, A3R25 and A3R26.
f.
g. 135 (Carrier): The 135 function is identical
to the 600 (carrier) function except that the
gain switching in the Input Amplifier is
accomplished by one section of the 135
function switch S7.
h. 75 UNBAL:
bypasses the balanced input circuitry and
transformer AlT1 and A1T2. Gain
The 75 UNBAL function
switching is performed by one section of
this function switch. When the 75 UNBAL
function is selected the output of the
balanced circuitry is disconnected. A 75
ohm termination is provided thru the
INPUT switch.
4-18. RANGE ATTENUATOR A2.
4-19. The RANGE attenuator adjusts the input signal
to a suitable level for the Input Amplifier. This
4-3
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Section IV
Model 3555B
Table 4-1. Range Attenuation and Amplifier Gain
RANGE
RANGE
Attenuation
80dB
ATTENUATOR
PADS USED
Setting
+30dBm
+20dBm
+10dBm
0dBm
-10dBm
-20dBm
-30dBm
-40dBm
-50dBm
-60dBm
-70dBm
-80dBm
Input Amplifier Gain
1,2,3
1,2,4
1,2
2,3
2,4
2
3
4
0
0
3.6dB
3.6dB
3.6dB
3.6dB
3.6dB
3.6dB
3.6dB
3.6dB
3.6dB
13.6dB
23.6dB
33.6dB
70dB
60dB
50dB
40dB
30dB
20dB
10dB
0dB
0dB
0dB
0dB
0
0
In positions 4 thru 12 (-SODBM thru +30DBM), A3R11 is
bypassed for maximum feedback. The gain of the
amplifier in these nine positions is a constant 2.5dB.
Potentiometer A3R26 is for calibration of the -80DBM
range, 600 ohm function. Resistor A3R27 is used to
maintain a charge on A3C22 to prevent transients when
changing ranges.
4-23. In order that the meter always indicate in DBM
regardless of the impedance selected, additional gain
switching must be performed. When the 75 function is
chosen, A3K2 energizes and places A3R16 in parallel
with A3R14 and A3R15. This reduces the negative
feedback (with respect to the 600 function) and
increases the amplifier gain by 9dB. When the 135
function is selected, A3R22/R23/R24 are connected in
series with A3R16. This combination is then in parallel
with A3R14 and A3R15, reducing the feedback and
increasing the amplifier gain by 6.4dB with respect to
the 600 function. When the 900 function is depressed,
A3R17, A3R19 and A3R20 are connected in parallel
with A3R13, increasing the negative feedback and
reducing the amplifier gain by 1.7dB. Relays A3K1 thru
A3K3 are controlled by the FUNCTION switch when any
of the impedance functions except 600 are selected.
4-24. Transistors A3Q1 and A3Q2 form a differential
amplifier. The signal is taken from the collector of
A3Q1, amplified by A3Q4 and A3Q5 with A3Q5
providing feedback to the base of A3Q2. Transistor
A3Q3 provides isolation between A3Q2 and A3Q4 to
prevent undesired feedback. This results in a greater
bandwidth than could be achieved without its use. The
output signal is coupled through A3R17 and A3C10 to
the INPUT switch.
4-25. FILTERS. (Schematic No. 3)
4-26. The 3555B contains a 3kHz FLAT weighting
filter, a C MSG weighting filter, a PROG weighting filter
and a 15kHz FLAT weighting filter. These active filters
consist of five amplifiers with controlled feedback for
waveshaping. They are used in combinations to form
these amplifiers are
Figure 4-4. Simplified Average Detection
4-4
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Model 3555B
Section IV
identical in operation, only the first will be discussed in
detail.
4-29. The 3kHz FLAT and 15kHz FLAT weighting
The only difference between these two active filters is in
the positive feedback used for shaping and in the
the assembly through pin 22. If C MSG is selected the
signal is first attenuated by A4R1, A4R2 and A4R3A.
Potentiometer A4R3A is for C MSG level adjustment for
0dB at 1kHz. The signal is then applied to the first in a
series of amplifiers. The first amplifier consists of A4Q1
through A4Q4. Differential amplifier A4Q1 and A4Q2
amplifies the signal and applies it to A4Q3 and A4Q4.
The emitter circuit of A4Q4 provides two feedback
signals, positive feedback through A4R8 and A4C4 to
the base of A4Q1 and negative feedback to the base of
A4Q2. The gain of this amplifier is controlled by the
ratio of the value of A4R10 to the value of A4R9. For
example, increasing the value of A4R9 would increase
the negative feedback and reduce the amplifier gain.
Gain can be calculated by the equation:
negative feedback used for gain.
The negative
feedback is altered by adding resistance to the feedback
divider at the base of A4Q12.
4-30. METER AMPLIFIER. (Schematic No. 4)
4-31. The meter amplifier consists of A3Q6 through
A3Q10. The signal is first amplified by differential
amplifier A3Q6 and A3Q7. The signal is taken from the
collector of A3Q6 and then amplified by A3Q9 and
A3Q10. Transistor A3Q8 provides isolation between
A3Q7 and A3Q9 to prevent undesired feedback. Two
signals are taken from A3Q10. The collector circuit
supplies a signal to the DIAL/AC MON jacks for the
purpose of listening to the measured signal. The emitter
circuit of A2Q10 provides a drive signal for the detector
circuit.
A4R10
Gain = 1 + A4R9
4-32. DETECTOR. (Schematic No. 4)
Positive feedback to the base of A4Q1 determines the
frequency response of this amplifier and is controlled by
the value of A4C4 and A4R8. All five of the amplifiers
are used in C Message weighting.
4-33. The detector is a class B rms detector which
combines the features of an average detector and a
peak detector. When the average detected signals and
the peak detected signals are combined in the proper
proportion an equivalent rms response is produced.
4-34. First consider the average detection in this
and A3Q15-A3Q16 are functionally symmetrical. This
means that A3Q14 and A3Q17 are driven by the same
signal. When the signal at the base of A3017 and
A3Q14 goes negative, A3Q! 4 turns on and A3Q17 turns
off. No current will flow through the meter. On the
positive half cycle A3Q14 turns off and A3Q17 turns on.
The current paths for the average detector are shown in
4-28. The Program weighting filter utilizes only
These amplifiers are identical to the one described in
the preceeding paragraph except for the value of the
positive feedback utilized for shaping and the negative
feedback used for gain control. This negative feedback
is modified by resistance in the feedback divider at the
base of A4Q12. Transistors A4Q5 and A4Q6 provide
additional gain required for Program weighting.
Potentiometer A4R3B is used for PROG level
adjustment at 1kHz.
Figure 4-7. Simplified Peak Detection
4-7
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Section IV
Model 3555B
no current flows through the meter from the peak
detector When A3Q14 is turned off and A3Q17 is turned
on, the current path is as shown by the heavy lines in
offset the junction drop of A3CR15 and A3CR16
respectively.
4-36. When the average detection and the peak
detector are combined in the proper proportion, an
equivalent rms response is produced. The advantage of
this type of rms detection is fast response.
4-37. POWER SUPPLY AND SERIES REGULATOR
(Schematic No. 4)
4-38. The 3555B can be operated from 115V or 230V
ac, the internal 48V dry cell battery or from a central
office battery (tip negative). When operating from an ac
source power is applied through transformer TI and the
AC/BAT switch S1 to the rectifier CR1. This rectified
voltage is filtered by C2 before being applied to the
series regulator through J2, S3, CR1 and cable W1.
4-39. The regulator is of the conventional series type
with A3Q19 acting as the sensing element and A3CR20
as the reference. Changes in the output level are
amplified by differential amplifier A3Q18 and A3Q19.
The output of the differential amplifier is amplified by
A3Q20 and applied to A3Q21 which controls the
conduction of the series transistor A3Q22. The output
of this series regulator is held at - 20 volts ±1 volt. The
maximum ac ripple and noise on the output voltage is
200mV rms.
4-40. It should be noted that when operating the set
from either the battery or from an ac source, capacitor
C2 will always be charged whether the set is turned on
or not. Caution should be exercised when servicing the
power supply.
4-8
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Model 3555B
Section V
SECTION V
MAINTENANCE
can be substituted provided they meet the required
specifications.
5-1.
5-2.
INTROOUCTION.
This section of the manual contains information
5-4.
5-5.
FACTORY SELECTED VALUES.
Factory selected values are denoted on the
necessary in the maintenance of the -hp- Model 3555B
Transmission and Noise Measuring Set. Included are
performance checks, adjustment and calibration
procedures and troubleshooting.
schematic diagrams by an asterisk. The nominal value
is shown. The value in your instrument may be different
or the part may be omitted.
5-3.
The test equipment needed to properly maintain
required specifications 'and recommended model. If the
recommended model is not available other equipments
5-6.
150 BAL CONVERSION.
a. To convert the 135 BAL function to a 150
BAL
Table 5-1. Required Test Equipment
INSTRUMENT
TYPE
Oscillator
RECOMMENDED
MODEL
-hp- 654A
REQUIRED CHARACTERISTICS
Frequency Range: 20Hz to 3MHz
Levels: -80dBm to +30dBm
Accuracy: ±0.1 5dB
Frequency Range: 100Hz to 20kHz
Amplitude: 30V
Oscillator
-hp- 201 C
Transformer
Voltmeter,
digital
Amplifier
Output:
Line matching
Function: AC and DC
Accuracy: ±.1%
Voltage gain: 20 dB
+/-20V peak at 0.5A peak
Frequency Range: 20Hz-4MHz
Accuracy: ±2%
50 ohms ±.25%
75 ohms ±.25%
-hp- 11004A
-hp- 3440A/3445A
-hp- 467A
Voltmeter, AC
-hp- 400FL
Termination
Termination
Cables
-hp- 11048B
-hp- 11094A
Trompeter Electronics
No. AD-1W
Balanced BNC to 310 plug
BNC to 358 plug
Adapter
Resistors
576 ohms ±1% (1)
875 ohms ±1% (1)
-hp- Part No. 06984598
(Use 825 ohm, 0757-0731 and
49.9 ohm, 0698A4110 in series)
-hp- Part No. 0698-6295
-hp- Part No. 0698-7408
-hp- Part No. 0698-7364
-hp- Part No. 0698-7363
Use 600 and 300 in series (0.1%)
-hp- Part No. 0698-6774
-hp- Part No. 0757-0465
300 ohms 0.1 % (4)
600 ohms ±0.1% (4)
135 ohms ±0.1%(4)
75 ohms ±0.1% (4)
900 ohms ±0.1%
150 ohms ±.1% (2)
100 kilohms 1% (1)
5-1
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Section V
Model 3555B
Figure 5-1. Balanced BNC to 310 Plug
function, remove or clip the shorting bar
b. Remove the 150 BAL decal from the small
envelope supplied with the set and stick it
over the existing 135 BAL decal.
FUNCTION........... CARRIER, 75 UNBAL
INPUT .................................TMS, TERM
RANGE......................................+10dBm
c. Adjust the 150 function as described in
b. Set the 654A frequency to 20kHz,
IMPEDANCE to 75 UNBAL and adjust the
output level for +10dBm. If the calibration
of the 654A is questionable, first connect
the output of the 654A through a 75 ohm
termination, directly to the input of the
3440A/3445A (3555B not connected) and
measure the voltage. This level should be
866mV rms. If it is not, adjust the 654A
amplitude control until it is and note the
654A meter indication for future reference.
Now that the 654A calibration has been
verified, disconnect
5-7.
5-8.
PERFORMANCE CHECKS.
The performance checks presented in this
section are in-cabinet checks designed to compare the
Model 3555B with its published specifications. These
checks can be used for incoming inspection, periodic
maintenance checks and to verify performance after
adjustment or repair. A performance check test card
appears at the end of this section which can be used to
record the specification performance of your set.
5-9.
LEVEL ACCURACY CHECKS.
a. Connect only the 654A and 3555B as
controls as follows:
Figure 5-2. Level Accuracy Check
5-2
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Model 3555B
Section V
Table 5-2. 75 UNBAL Carrier Accuracy Check
3555B INDICATION (dBm)
RANGE
FREQUENCY
30Hz to 1MHz
100Hz to 600kHz
1MHz to 3MHz
+10dBm
0dBm
+10 ±0.5
0 ±0.5
+10 ±0.2
0 ±0.2
-10 ±0.2
-20 ±0.2
-30 ±0.2
-40 ±0.2
-50 ±0.2
+10 ±0.5 ±10% of meter indication in dBm
0 ±0.5 ±10% of meter indication in dBm
-10 +0.5 ± 0% of meter indication in dBm
-20 ±0.5 ±10% of meter indication in dBm
-30 ±0.5 ±10% of meter indication in dBm
40 ±0.5 ±10% of meter indication in dBm
-50 ±0.5 ±10% of meter indication in dBm
-10dBm
-20dBm
-30dBm
-40dBm
-50dBm
-10 ±0.5
-20 ±0.5
-30 ±0.5
-40 ±0.5
-50 ±0.5
the 3440A/3445A and reconnect the output
of the 654A to the input of the 3555B.
Maintain the 654A meter reference
throughout the remainder of the following
checks.
l.
Tune the 201 C from 100Hz to 20kHz,
maintaining 7.75V on the 3440A/3445A.
Between 100Hz and 15kHz, the 3555B
indication must not change more than
±0.2dBm. Between 15 kHz and 20kHz, the
indication must not change more than
±0.5dBm.
c. The 3555B meter should indicate 0dBm
±0.1 dBm.
d. Check all the RANGES and frequencies
tolerances. Be sure to maintain the 654A
reference established in step b.
e. Change the 654A to 600 BAL and change
the 3555B to CARRIER, 600 BAL.
Connect the 654A 600 BAL output to the
3555B input using a balanced cable.
m. Check the +30dBm range using the
procedure described in Steps j through 1,
except change the 3555B range to +30dBm
and change the 201C output level for
24.49V.
n. To check the 900 ohm function on the
+20dBm and +30dBm ranges, connect a
300 ohm +0.1% resistor in series with the
f.
Check the RANGES and frequencies in
described for the 75 UNBAL function.
o. Change the 3555B to 900 BAL and change
the range to +20dBm.
g. Change the 654A to 135 BAL and change
the 3555B to 135 BAL. Repeat step e for
the same RANGES and tolerances
indicated for the CARRIER 600 BAL
h. Change the 3555B to VF/Nm, 600 BAL and
change the 654A to 600 BAL. Check the
for the tolerances indicated.
p. Adjust the 201 C output for 9.49V as
indicated on the 3440A/3445A.
r.
Change the 3555B range switch to +30dBm
and adjust the 201C for 30V on the
3440A/3445A. Check for the tolerances
range.
i.
j.
Change the 3555B to 900 BAL and connect
a 150 ohm ± 1% resistor in series with each
input lead. Readjust the 654A for 0dBM.
same tolerances.
To check the top two ranges, connect the
the 3555B controls as follows:
Table 5-3. Carrier Level Accuracy
3555B Indication (dBm)
RANGE
135 1kHz -600kHz
600 1kHz - 150kHz
10kHz - 300kHz
10kHz - 100kHz
-50 thru +10dBm
±0.5
±0.2*
FUNCTION....... VF/Nm 600 BAL
INPUT .................... TMS, TERM
RANGE..........................+20dBm
*Increase specification by ±0.3dB on 135 ohms (or 150
ohms) when not battery powered.
k. Adjust the 201C for 7.75V on the
3440A/3445A at 100Hz.
5-3
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Section V
Model 3555B
Figure 5-3. +20dBm and +30dBm Level Accuracy Check
FUNCTION..................VF/Nm, 600 BAL
5-10. RETURN LOSS CHECK.
INPUT ................................TMS, TERM
RANGE ........................................0dBm
a. To make a return loss check it will first be
necessary to construct a balanced bridge
utilizing 0.1% resistors for each of the four
equipment test set-up to be used. For this
check to be meaningful, all test leads
should be kept short. The leads connecting
the 3555B to the bridge should be short clip
leads and should be kept away from each
other and from other leads. Keep all the
instruments away from other instruments
that may be referenced to earth ground.
NOTE
The 3555B does not have to be
turned on for this check. If at any
frequency the 3555B return loss
check is out of specification, check
the reference at that frequency as
described
in
the
following
procedure.
c. Set the 654A frequency to 1kHz.
adjust the 654A output level for an up scale
indication on the 400FL AC Voltmeter.
Table 5-4. VF/Nm Level Accuracy Checks 600 BAL and 900 BAL
-80dBm through +30dBm
RANGE
+30dBm
+20dBm
+10dBm
0dBm
-10dBm
-20dBm
-30dBm
-40dBm
-50dBm
-60dBm
-70dBm
-80dBm
20Hz to 20kHz
40Hz to 15kHz
100Hz to 20kHz
+30 ±0.5
100Hz to 15kHz
+30 ±0.2
+20 ±0.5
+20 ±0.2
+10 ±0.2
+10 ±0.5
0 ±0.5
-10 ±0.5
-20 ±0.5
-30 ±0.5
-40 ±0.5
-50 ±0.5
-60 ±0.5
-70 ±0.5
-80 ±0.5
0 ±0.2
-10 ±0.2
-20 ±0.2
-30 ±0.2
40 ±0.2
-50 ±0.2
-60 ±0.2
5-4
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Model 3555B
Section IV
Figure 5-4. Return Loss Test Set-Up
d. Open S1 and down range the 400FL for an
on-scale indication. This indication
h. Change the 3555B FUNCTION to
CARRIER 600 BAL and repeat steps f and
g between 3kHz and 150kHz. Return loss
must be at least 26dB down from the
reference.
subtracted from the reference established
in step c, is the bridge balance and should
be greater than the return loss
specification.
i.
900 ohms f 0.1% (use 300 ohms + 0.1% in
series with 600 ohms ±0.1%) and change
the 3555B FUNCTION to VF/Nm 900 BAL.
Be sure to reset the reference level after
connect the 3555B tip and ring in its place.
Be sure to use short clip leads.
f.
Momentarily close S1 and recheck the
reference on the 400FL. .Open S1 in
on-scale indication. This indication must
be down at least 30dB from the reference.
the resistors are changed.
Check the
return loss between 50 Hz and 20 kHz.
The return loss must be better than 30 dB.
g. Tune the 654A from 50Hz to 20kHz. The
400FL indication must remain at least 30dB
down from the reference.
FIG 5-1
Figure 5-5. Filter Response Test Set-UP
5-5
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Section V
Model 3555B
Figure 5-6. Bridging Loss Test Set-Up
j.
135 ohms +0.1% and change the 3555B
FUNCTION to 135 BAL. Check the return
1. Connect the equipment as shown in
set the 3555B controls as follows:
loss between 1kHz and 600kHz.
The
return loss must be better than 26dB down
from the reference.
FUNCTION......... VF/Nm 600
INPUT ............ NOISE BRDG
RANGE .......................0dBm
k. Change the 3555B input connection to the
75 UNBAL jack. Change the resistors in
the 3555B FUNCTION to CARRIER 75
UNBAL.
2. Adjust the output of the 654A for
0dBm at a frequency of 1 kHz.
l.
Check the return loss between 1kHz and
3MHz. The return loss must be better than
30dB down from the reference.
b. 3kHz FLAT FILTER RESPONSE
1. Set the 654A frequency to 1kHz and
adjust the output level for 0dBm.
5-11. FILTER RESPONSE CHECKS.
a. C MSG FILTER RESPONSE
c. 15kHz FLAT FILTER RESPONSE
Table 5-5. Filter Response Checks
FREQUENCY
C MSG (dBm)
3kHz FLAT (dBm)
0 ±1.75
15kHz FLAT (dBm)
0 ±1.75
PROGRAM (dBm)
60Hz
200Hz
250Hz
500Hz
1kHz
2kHz
2.5kHz
3kHz
4kHz
5kHz
6kHz
8kHz
-55.7 ±2
-25 ±2
-17.3 ±2
0 ±1
0 ±1
-7.5 ±1
0(Ref)
-1.3 ±1
-1.4 ±1
-6.6 ±1
0(Ref)
4.8 ±2
0(Ref)
-0.5 ±1.75
-1.5 ±2
-3 ±3
0(Ref)
+6.5 ±2
+6.5 ±2
+6.5 ±2
+6.4 ±3
+4 ±3
-14.5 ±3
-28.5 ±3
0 ±1
10kHz
12.5kHz
15kHz
-0.5 ±1.75
-1.5 ±2
-3 ±3
-8.5 ±4
5-6
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Model 3555B
Section V
1. Reset the 654A output level for 0dBm
indication on the 3555B meter at a
frequency of 1kHz.
f.
With the 400FL set to the 0dB range, adjust
the 654A output level for exactly 0dB
indication on the 400FL.
g. Change the 3555B FUNCTION to VF/Nm
900 and connect the 3555B input to the
d. PROG FILTER RESPONSE
400FL input terminals.
The 400FL
1. Reset the 654A frequency to 1kHz and
adjust the output level for 0dBm
indication on the 3555B meter.
indication must not drop by more than
0.3dB.
5-13. INPUT BALANCE.
a. Set the 3555B controls as follows:
FUNCTION ............VF/Nm 600
5-12. BRIDGING LOSS.
INPUT...................TMS BRDG
FUNCTION ............VF/Nm 600
INPUT...................TMS BRDG
RANGE.......................... 0dBm
b. Adjust the output of the 654A (600 ohm
function) for 0dBm indication on the 400FL
at a frequency of 1kHz.
RANGE.......................... 0dBm
b. Connect the 654A 600 ohm output to-the
tip and ring input of the 3555B. Set the
output frequency of the 654A to 60Hz and
adjust the amplitude control for 0dBm
indication on the 3555B meter.
c. Change the equipment setup to that shown
c. Connect the 3555B to the 400FL input.
The indication on the 400FL should not
drop more than 0.3dB.
d. Change the FUNCTION switch to
CARRIER 600 and repeat the above
procedure at a frequency of 10kHz. The
400FL indication should not drop by more
than 0.05dB.
d. Change the 3555B RANGE switch to
-80dBm. The 3555B indication (meter +
RANGE setting) must be down at least
80dB.
e. Change the 3555B RANGE switch to
-70dBm and tune the 654A to 6kHz. The
3555B indication must be down at least
70dB.
e. Change the equipment setup by connecting
a 300 ohm ±1% resistor in series with the
400FL input and change the resistor
connected across the 400FL input to 900
ohms ±1%.
f.
Change 3555B RANGE to -60dBm and
tune the 654A to 20kHz. The 3555B
indication must be down at least 50dB.
g. Change the 3555B FUNCTION switch to
Figure 5-7. Input Balance Test Set-Up
5-7
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Section V
Model 3555B
CARRIER 600 and repeat the above
procedure. Between 1kHz and 10kHz, the
balance must be greater than 70dB.
Between 10kHz and 100kHz, the balance
must be better than 60dB. Between 100kHz
and 600kHz, balance must be better than
40dB.
c. Set the 654A meter for a reference indication
and be sure to maintain this indication
throughout the following procedures unless
otherwise instructed.
3440A/3445A voltmeter.
Disconnect the
d. Change the 654A to -50dBm and change the
3555B RANGE switch to -50dBm.
e. Disconnect the 3440A/3445A, the 11094A
termination and the cable. Connect the
654A output directly to the 3555B input.
5-14. ADJUSTMENT
PROCEDURE.
5-15. The following is a complete adjustment and
calibration procedure for the Model 3555B. These
adjustments should be performed only after it has been
determined by the performance checks that the set is not
operating within its published specifications.
5-16. POWER SUPPLY CHECK.
AND
CALIBRATION
f.
Adjust A3R43 for 0dBm indication on the
3555B meter.
g. Change
654A
frequency
to
3MHz
maintaining the reference established on the
654A meter.
h. Adjust A3C8 for 0dBm indication on the
3555B meter.
5-17. Before attempting the following calibration
procedures, first check the power supply voltage to be
sure that it is correct and that the ripple voltage is not
abnormal. To do this perform the following steps.
NOTE
5-19. ATTENUATOR CALIBRATION.
a. Remove the FUNCTION board and replace it
with the test board supplied with the set.
b. With the equipment and controls set as in
the preceding check, change the 3555B
RANGE to 40dBm and change the 654A
attenuator to -40dBm. Change the 654A
frequency to 100kHz.
Calibration of the 3555B should be
performed with the set operating from
the internal battery except for the
power supply ripple check in the
following steps. Operate the set from
the ac power source long enough to
make this check and then return the
set to internal battery operation. This
is accomplished by changing the
position of the slide switch mounted
on the side of the set. When operating
from the battery, disconnect the ac
power cord from the set.
c. Adjust A2C12 for 0dBm indication on the
3555B meter.
d. Change the 3555B RANGE switch to
-30dBm and change the 654A attenuator to -
30dBm. Adjust A2C7 for 0dBm indication on
the 3555B meter.
e. Change the 3555B RANGE switch to
-20dBm and change the 654A attenuator to -
20dBm. Adjust A2C4 for 0dBm indication on
the 3555B meter.
a. Remove the set from the case and connect
the 3440A/3445A dc voltmeter between the -
20V supply and ground. The negative side
of A3C34 is a convenient place.
f.
Change the 3555B RANGE switch to
+10dBm and change the 654A attenuator to
+10dBm. Adjust A2C1 for 0dBm indication
on the 3555B meter.
b. Turn the set on. The 3440A/3445A should
indicate -20 volts ±1.0V.
the tolerance indicated. If any of the checks
tolerances, repeat steps b through f.
c. Connect the 400FL AC Voltmeter to the
negative side of A3C34 and measure the
ripple voltage. The maximum allowable
ripple is 200uV rms.
5-20. FUNCTION CALIBRATION.
5-18. 75 UNBAL CALIBRATION.
a. Remove the test board from the set and
install the function board assembly. Connect
the 654A balanced output to the 3555B
Set the 3555B controls as follows:
a. Connect the 654A and 3440A/3445A as
controls as follows:
FUNCTION ................ 75 UNBAL
INPUT..................... TMS, TERM
RANGE..........................+10dBm
FUNCTION........ CARRIER, 600 BAL
INPUT ........................... TMS, TERM
RANGE ................................ -50dBm
b. Set the 654A frequency to 10 kHz, 75
UNBAL, and adjust the output level for 866
mV (+ 10 dBm) indication on the
3440A/3445A.
b. Set the 654A frequency to 10kHz and adjust
the output attenuators for -5OdBm output
level, using the 600 BAL output function.
5-8
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Model 3555B
c. Adjust A3R15 for 0dBm indication on the
Section V
RESPONSE............................. DAMP
3555B meter.
d. Change the 654A frequency to 1kHz.
Change the 3555B FUNCTION switch to
VF/Nm, 600 BAL. Compare the 3555B
meter indication with the indication in step
c. If any difference exists, adjust A3R15 to
split the difference between these two
indications.
c. Set the 654A (600 BAL) output level to
0dBm at a frequency of 20Hz. The 3555B
+0.3dBm. Note this indication.
d. Change the 654A output level to -70dBm at
a frequency of 20Hz. Change the 3555B
RANGE switch to -70dBm and change the
FUNCTION to VF/Nm 600 BAL.
The
NOTE
3555B meter should indicate 0dBm
+0.3dBm. Note the exact indication.
If the set is being operated from the
ac line ground currents may be
encountered on the low ranges,
particularly if other instruments are
connected in any way to the 3555B.
In order to eliminate this problem,
operate the set from its own internal
battery or use the C MSG filter. If the
C MSG filter is used, perform the
e. Compensation should be made between
the 900 BAL, 0dBm check (step c) and the
600 BAL, -70dBm check (step d). To raise
the level, increase the value of A3R72 until
the 900 BAL 0dBm check indicates high by
the same amount that the 600 BAL, -
70dBm check indicates low. The total
difference should not exceed +0.3dBm.
5-22. COMMON MODE ADJUSTMENT.
FUNCTION ................VF/Nm, 600 BAL
INPUT...............................TMS, TERM
RANGE.......................................0dBm
b. Set the 654A frequency to 20kHz and
adjust the output level of the 654A for
0dBm indication on the 3555B meter.
filter
calibration
described
in
following step.
e. Change the 654A to -80dBm output .level
at 1.00kHz. Change the 3555B RANGE
switch to -80dBm. Adjust A3R26 for 0dBm
indication on the 3555B meter.
f.
Change the 654A to 135 BAL (150 BAL)
and change the 3555B FUNCTION to 135
BAL (I50 BAL). Adjust A3R24 for 0dBm
indication on the 3555B meter.
c. Disconnect the left output terminal on the
654A and short the tip and ring together on
the cable. Down range the 3555B RANGE
switch for an on-scale indication.
d. Adjust A1C7 for minimum indication on the
3555B meter. This indication must be
down at least 60 dB.
e. Change the 3555B FUNCTION switch to
CARRIER, 600 BAL and change the 654A
frequency to 100kHz.
g. Change the 3555B RANGE switch to -
5OdBm, INPUT switch to TMS TERM, and
the FUNCTION switch to VF/Nm 600 BAL.
Change the 654A to 1kHz at an output
level of -50dBm, 600 BAL. Adjust the
AMPLITUDE control for exactly 0dBm
indication on the 3555B meter.
h. Change the 3555B FUNCTION switch to
900 BAL without changing anything else.
Adjust A3R20 for -0.15dBm indication on
the 3555B meter.
f.
Use the procedure described above and
adjust A1C4 for minimum indication on the
3555B meter. This indication must be
down at least 40dB.
5-21. FREQUENCY RESPONSE ADJUSTMENT.
a. The following adjustment consists of
selecting fixed values for frequency
compensation at 20Hz, 600 BAL, -70dBm
and 20kHz, 600 BAL, -70dBm.
5-23. BALANCE CHECK.
a. First check the balance as described in
does not meet specifications. If it does,
disregard this step. If it does not perform
the following procedure.
b. Connect the 654A 600 BAL output to the
3555B input. Set the 3555B controls as
follows:
b. Since there are no adjustments for balance
it will be necessary to change the value of
a fixed factory selected capacitor. To
adjust the balance on the
FUNCTION ............... VF/Nm 900 BAL
INPUT............................. TMS, TERM
RANGE..................................... 0dBm
5-9
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Section V
Model 3555B
CARRIER function, change C4. To change
the balance on VF/Nm, change the value of
A1C9.
c. Remove the two screws that secure the A3
board.
d. Gently lift up the bottom of the A3 board to
unplug it from the A1 FUNCTION
assembly.
e. Hold the bottom of the A3 board high
enough to clear the FUNCTION board and
pull the A3 assembly out. This is easily
accomplished by gently rocking the board
back and forth while pulling it down (toward
the FUNCTION board).
c. To determine whether the value of these
capacitors should be increased or
decreased, lightly touch the tip and ring
banana jack insulators and watch the
direction in which the meter indication
goes. The side (tip or ring) that causes the
meter indication to decrease needs added
capacitance. The capacitance should be
changed in very small steps and checked
again.
f.
Once the A3 assembly has been removed,
the AI FUNCTION board can be removed
by pulling it out.
5-24. FILTER CALIBRATION.
g. To gain access to the RANGE attenuator
(A2), Input switch and the NOISE WTG
switch, the shield must be removed. To do
this, remove the two screws on each side
of the set and lift out the shield.
controls as follows:
FUNCTION ................VF/Nm, 600 BAL
RANGE.......................................0dBm
INPUT........................... NOISE, TERM
NOISE WTG.......................3kHz FLAT
h. To reassembly the set, use the reverse of
the procedure described above.
5-27. TROUBLESHOOTING PROCEDURES.
5-28. The following information is supplied to assist in
locating a malfunction in the set in a minimum of time.
It should first be determined that a malfunction does
indeed exist and that the trouble is not external to the
set.
5-29. Before starting to troubleshoot the set, use the
front panel controls to determine exactly which function,
this analysis. In many cases a good front panel analysis
of the symptoms can lead you directly to the trouble.
5-30. To simplify troubleshooting the following
information is supplied:
b. Connect a frequency counter to the 3555B
AC MON terminals and adjust the 654A
frequency to exactly 1.00kHz as indicated
on the frequency counter. Adjust the 654A
output level for exactly 0dBm.
c. Adjust A4R3C for 0dBm indication on the
3555B meter.
d. Change the NOISE WTG switch to 15kHz
FLAT and note the meter indication. If it
differs from the indication set up in step c,
adjust A4R3C to split the difference
between these two indications.
a. Troubleshooting
Tree
-
-
The
e. Change the 3555B NOISE WTG switch to
C MSG and adjust A4R3A for 0dBm
indication on the 3555B meter.
on the half-split method of troubleshooting
a set. The trouble can be isolated to a
general area or block using this tree. Once
the trouble has been isolated to an area, a
reference is given. to a paragraph where
more specific information can be found.
b. Functional Block Diagram - - The functional
block diagram can also be used to isolate
the trouble to block. The diagram contains
all of the essential blocks that make up the
set and includes voltage levels, test points
and adjustments. The troubleshooting tree
and functional block diagram are keyed
together by the numbers with a circle
around them. If the levels or indications in
your set do not agree with those on the
functional block diagram or troubleshooting
tree, refer to the paragraph indicated for
more detailed information.
f.
Change the 654A frequency to 3.00kHz
and adjust A4R3D for an indication of -
2.15dBm on the 3555B meter.
g. Repeat steps e and f until both points are
within specifications.
h. Change the 3555B NOISE WTG switch to
PROG and change the 654A frequency
back to 1.001Hz with the output level still
set to 0dBm. Adjust A4R3B for 0dBm
indication on the 3555B meter.
5-25. ASSEMBLY REMOVAL.
5-26. To gain access to the various assemblies in the
3555B use the following procedure.
a. Turn the set off and. remove it from the
case by removing four front panel screws.
b. Unplug the small cable on the A3
assembly.
5-10
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Section V
Model 3555B
Table 5-6. Front Panel Trouble Analysis
3555B SHOULD INDICATE
(RANGE + METER)*
In green area, BAT GOOD
SET ACTUALLY
INDICATES
CORRECTIVE
ACTION
Replace battery
INPUT CONDITIONS
FUNCTION: VF/Nm
FUNCTION
DIAL BAT
1kHz, 0dBm, 600 BAL
Input: TMS, TERM
VF/Nm: 600 BAL
0dBm ±0.2dBm
Change INPUT to BRDG
RANGE to +10dBm
+6dBm ±0.2dBm
Depress 900 BAL
+4.2dBm ±0.2dBm
INPUT to TERM
RANGE to 0dBm
-0.1 5dBm ±0.2dBm
0dBm
FILTERS
INPUT: NOISE TERM
NOISE WTG: 3kHz FLAT
VF/Nm, 600 BAL
0dBm ±0.2dBm
0dBm +±0.2dBm
0dBrn ±0.2dBm
0dBm ±1dBm
Change to C MSG
Change to 15kHz FLAT
Change to PROG
FUNCTION: CARRIER
20kHz, 0dBm
600 BAL
INPUT: TMS, TERM
FUNCTION: CARRIER
600 BAL
0dBm
Refer to Paragraph 5-34
Change INPUT to BRDG
RANGE to +10dBm
+6dBm ±0.5dBm
+12.6dBm ±0.5dBm
-2.2dBm ±0.5dBm
0dBm ±0.2dBm
Depress 135 BAL
RANGE to +20dBm
Change INPUT to TERM
RANGE to 0dBm
Change to 75
UNBAL INPUT: TMS, TERM
FUNCTION: 75 UNBAL
RANGE: 0dBm
Change INPUT to BRDG
RANGE to 10dBm
±6dBm +0.2dBm
0dBm ±0.2dBm
Change INPUT back to
TERM
RANGE to 0dBm
RANGE
1kHz, 600 BAL,
LEVEL +10dBm
Change RANGE to +10dBm
FUNCTION: VF/Nm 600 BAL
Change RANGE to -10dBm
+10dBm ±0.2dBm
-10dBm ±0.2dBm
LEVEL -10dBm
LEVEL -20dBm
Change RANGE to -20dBm
-20dBm ±0.2dBm
5-12
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Model 3555B
Section V
Table 5-6. Front Panel Trouble Analysis (Cont'd)
3555B SHOULD INDICATE
(RANGE + METER)*
SET ACTUALLY
INDICATES
CORRECTIVE
INPUT CONDITIONS
FUNCTION
ACTION
LEVEL -30dBm
LEVEL 40dBm
LEVEL -500dBm
LEVEL -60dBm
LEVEL -70dBm
LEVEL -80dBm
LEVEL 0dBm
Change RANGE to -30dBm
Change RANGE to 400dBm
Change RANGE to -50dBm
Change RANGE to -60dBm
Change RANGE to -70dBm
Change RANGE to -80dBm
-30dBm ±0.2dBm
-40dBm ±0.2dBm
-50dBm ±0.2dBm
-60dBm ±0.2dBm
-70dBm ±0.2dBm
-80dBm ±0.2dBm
RANGE to 0dBm
0dBm
INPUT: TMS, TERM
Measure 270mV ac
±0.2dBm at
AC MON jacks
NG CHECK
75 UNBAL, Connect
UNBAL signal
RANGE: 0dBm
FUNCTION: VF/Nm
600 BAL
Adjust oscillator
level for 0dBm
on 3555B meter
between tip and ring
Change input
Depress NG button
-40dBm
connection. Connect
signal between tip
and ring and sleeve
(tip and ring shorted
together), ground
lead to sleeve
Change RANGE to 40dBm
*Some meter jitter may
be experienced, but the
reading should be within
the tolerance indicated.
c. Schematics-- The schematic diagrams
contain dc voltage levels and signal levels
indicated in column 3, refer to the "corrective action"
column.
for a specified input condition. This will
NOTE
assist in troubleshooting individual circuits.
This table is designed to help locate
catastrophic failures. If your set is
only out of the specified tolerances,
5-31. FRONT PANEL TROUBLESHOOTING.
5-32. Before attempting to troubleshoot the set, first
determine from the front panel controls exactly which
functions are performing properly and which ones are
not. In this way, many troubles can be isolated to a
specific area and sometimes to a component.
a
complete
adjustment
and
calibration procedure should be
checking out the front panel controls.
This table
5-34. FUNCTION TROUBLESHOOTING.
a. First determine from the Front Panel
the probable cause of the malfunction in
the FUNCTION switch assembly.
indicates what the results should be for each check
along with the specified tolerance. A space is provided
to enter your results. If these spaces are completed for
each check, they will be of great assistance in making
further troubleshooting checks.
Whenever
a
discrepancy exists between your results and those
5-35. RANGE TROUBLESHOOTING.
5-13
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Section V
Model 3555B
Table 5-7. Function Troubleshooting
properly, check the relay and the
energizing ground supplied through either
pins 1, 2 or 3 on XA1.
DEFECTIVE
FUNCTION
5-37. FILTER TROUBLESHOOTING.
VF/Nm
CARRIER
a. First determine that the set is operating in
the TMS input mode. This bypasses the
filters. If the set functions properly in the
TMS mode, check each of the filters by
applying a 1kHz signal at a 0dBm level to
the set. All filters are calibrated for 0dBm
indication on the 3555B meter at a
frequency of 1kHz.
used in C MSG, the loss of any one will
obviously cause the loss of the C MSG
weighting. However, the bad amplifier can
be isolated by checking the other filters.
Use the following guide to isolate the
trouble to a particular amplifier.
75 UNBAL
135 BAL
A3K2
A1T2, A3K3,
A3R22,A3R23,
A3L1, A3R24
600 BAL
600 BAL
900 BAL
A1T2
A1T1
A1T1, A3K1,
A3R19, A3R20
NG
A1R5 thru
A1R8, A1C1,
A1S3
1. First be sure that the filters have the
correct operating potential applied.
Check the voltage at the junction of
A4R49 and A4C33 to be sure that
there is -20 volts + 1 volt.
HOLD
L1A/B, A1S1
S1
2. If none of the filters work, check A3 in
3. If the PROG filter does not work but
the others do, check A6 (A4Q5 and
A4Q6).
DIAL BAT
A1S2, A3R59
a. First determine from the Front Panel
which range or ranges are defective.
changes that take place when switching
ranges. Select the attenuator pads and/or
gain switching resistors that match your
symptom and check them.
4. If C MSG does not work but the others
do, check A1, A4 and A5.
c. After the trouble has been isolated to an
amplifier, check the dc potentials indicated
on the schematic diagram.
This will
normally isolate the trouble to
a
component. If the dc levels are correct but
the filter response is out of tolerance, no
attempt should be made to change the filter
characteristics. Return the filter to your
nearest -hp- Sales and Service office listed
in the back of this manual.
5-36. TROUBLESHOOTING
AMPLIFIER.
THE
INPUT
a. Check the dc voltages as indicated in
failure does exist. If the dc voltages are
abnormal (greater than + 10% of the
indicated level), check for open or shorted
components in the area of the abnormal
indication.
b. Check to see that A3K1, A3K2 and A3K3
are operating properly. All relays are de-
energized when either of the 600 BAL
FUNCTION pushbuttons is depressed.
Depress each of the other impedance
functions (900 BAL, 135 BAL and 75
UNBAL) to see that A3K1, A3K3 and A3K2
respectively, energize and de-energize
properly. If any relay fails to operate
5-38. TROUBLESHOOTING
AMPLIFIER AND DETECTOR.
THE
METER
a. Inject a 1kHz, 0dBm signal (.775V rms) into
the 3555B and set the INPUT switch to
TMS TERM, RANGE to 0dBm and the
FUNCTION to VF/Nm, 600 BAL. Measure
the signal at the input of the meter
amplifier (XA3 pin 9). The signal level
should be 6.2mV rms.
If not the
malfunction is ahead of the meter amplifier
5-14
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Model 3555B
Section V
Table 5-8. FUNCTION Switch Resistance Values
NOTE
The following resistance measurements were made with C1 shorted. Be sure to
remove the short after completion of your measurements.
INPUT JACKS
DIAL/AC MON JACKS
Ring to Ground
BRDG TERM
FUNCTION
Tip to Ring
BRDG TERM
Tip to Ground
BRDG TERM
DIAL BAT
NG
80.4 kilohms
80.4 kilohms
80.4 kilohms
700 ohms
NG HOLD
VF/Nm
900 BAL
900 ohms
400 ohms
600 ohms
350 ohms
DIAL JACKS, resistance is
infinite Tip to Ring, Tip to
Ground and Ring to
900 BAL HOLD
600 BAL
Ground on all functions.
600 BAL HOLD
CARRIER
600 BAL
600 ohms
600 ohms
135 ohms
135 ohms
BRDG:
600 BAL HOLD
135 BAL
135 BAL HOLD
75 UNBAL, to Ground
100 kilohms,
120 kilohms,
400 kilohms,
75 ohms
-30dBm thru +30dBm ranges
40dBm Range
-50dBm thru -80dBm ranges
TERM:
b. With a 6.2mV rms signal at XA3 pin 9,
measure the signal at XA1, pin 6 or at the
AC MON jacks. This signal should be
270mV rms ± l10o. If not, check A3Q6
c. If a 270mV rms signal appears at the AC
MON jacks, check the detector circuit
(A3Q11 through A3Q17).
5-39. FACTORY SELECTED VALUES.
through
A3Q10
and
associated
components in the Model 3555B, along with the purpose
of each. Nominal values are shown on the schematic
components, using the dc levels indicated
5-15
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Section V
Model 3555B
Table 5-11. Factory Selected Values
Table 5-9. Range Attenuation and Amplifier Gain
Attenuator Pads Used
Amplifier Gain
Switching
Designator
C4
Purpose
Adjust balance at 600kHz, 135 BAL
RANGES
1
2
3
4
A1C5
A1C9
Padding capacitor for A1 C4
Adjust balance 20kHz, 600 BAL (VF/Nm)
+30
+20
+10
0
-10
-20
-30
-40
-50
-60
-70
-80
X
X
X
X
X
X
X
X
X
X
X
A1C8
Padding capacitor for A1C7
X
X
X
X
A1C10 and
A1R12
A1R14
Frequency response correction for A1TI
600 BAL, VF/Nm calibration
A3C1
Padding capacitor for A2C12
A2R13, A2R14
A2R13
A3C15
Frequency response, 20Hz, -80dBm, 600
BAL (VF/Nm)
Ranges Affected +30 -20 +30 +20
If Defective +20 thru -10
+10 +30 -30 -40
-60 and -70
A3R46
A3R72
Adjust the bias level for A3Q10 (-10V at +
side of A3C24)
0
Response, 20Hz, 600 BAL (VF/Nm)
-70dBm and 20Hz, 900 BAL, 0dBm.
Compromise between these two settings.
A3R74and
A3R75
Meter tracking at 1/3 full scale. Resistors
should be the same value.
Table 5-10. Resistance Checks
RANGE (dBm)
-50 thru +30
Pin 1 to 3
154 kilohms
13 kilohms
2.33 kilohms
0
Pin 2 to 3
0
28.64 kilohms
28.64 kilohms
28.64 kilohms
Pin 1 to 2
Infinity
41.6 kilohms
31 kilohms
28.64 kilohms
-60
-70
-80
5-16
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PERFORMANCE CHECK TEST CARD
Tests Performed By
Date
CHECK
Hewlett-Packard Model 3555B
Transmission and Noise Measuring Set
Serial No.
DESCRIPTION
CARRIER 75 UNBAL
LEVEL ACCURACY CHECK
30Hz to 1MHz
+10dBm Range
0dBm Range
-10dBm Range
-20dBm Range
-30dBm Range
+10dBm ±0.5dBm
0dBm ±0.5dBm
-10dBm ±0.5dBm
-20dBm ±0.5dBm
-30dBm ±0.5dBm
-40dBm ±0.5dBm
-50dBm ±0.5dBm
-40dBm Range
-50dBm Range
100Hz to 600kHz
+10dBm Range
0dBm Range
+10dBm ±0.2dBm
0dBm ±0.2dBm
-10dBm Range
-20dBm Range
-30dBm Range
-40dBm Range
-50dBm Range
-10dBm ±0.2dBm
-20dBm ±0.2dBm
-30dBm ±0.2dBm
-40dBm ±0.2dBm
-50dBm ±0.2dBm
1MHz to 3MHz
+10dBm Range
0dBm Range
+10dBm ±0.5dBm ±10% of meter indication
0dBm ±0.5dBm ±10% of meter indication
-10dBm ±0.5dBm ±10% of meter indication
-20dBm ±0.5dBm ±10% of meter indication
-30dBm ±0.5dBm ±10% of meter indication
-40dBm ±0.5dBm ±10% of meter indication
-50dBm ±0.5dBm ±10% of meter indication
-10dBm Range
-20dBm Range
-30dBm Range
40dBm Range
-50dBm Range
CARRIER 135 BAL
LEVEL ACCURACY CHECK
1kHz to 600kHz
+10dBm Range
0dBm Range
+10dBm ±0.5dBm
0dBm ±0.5dBm
-10dBm ±0.5dBm
-20dBm ±0.5dBm
-30dBm ±0.5dBm
-40dBm ±0.5dBm
-50dBm ±0.5dBm
-10dBm Range
-20dBm Range
-30dBm Range
-40dBm Range
-50dBm Range
10kHz to 300kHz
+10dBm Range
0dBm Range
+10dBm ±0.2dBm
0dBm ±0.2dBm
-10dBm Range
-20dBm Range
-30dBm Range
-40dBm Range
-50dBm Range
-10dBm ±0.2dBm
-20dBm ±0.2dBm
-30dBm ±0.2dBm
-40dBm ±0.2dBm
-50dBm ±0.2dBm
(1)
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PERFORMANCE CHECK TEST CARD (Cont'd)
CARRIER 600 BAL
LEVEL ACCURACY CHECK
1kHz to 150kHz
+10dBm Range
+10dBm ±0.5dBm
0dBm ±0.5dBm
-10dBm ±0.5dBm
-20dBm ±0.5dBm
-30dBm ±0.5dBm
-40dBm ±0.5dBm
-50dBm ±0.5dBm
0dBm Range
-10dBm Range
-20dBm Range
-30dBm Range
-40dBm Range
-50dBm Range
10kHz to 100kHz
+10dBm Range
+10dBm ±0.2dBm
0dBm ±0.2dBm
0dBm Range
-10dBm Range
-20dBm Range
-30dBm Range
-40dBm Range
-50dBm Range
-10dBm ±0.2dBm
-20dBm ±0.2dBm
-30dBm ±0.2dBm
-40dBm ±0.2dBm
-50dBm ±0.2dBm
VF/Nm 600 BAL and 900 BAL
LEVEL ACCURACY CHECK
20Hz to 20kHz
600 ohms
900 ohms
0dBm Range
0dBm ±0.5dBm
-10dBm ±0.5dBm
-20dBm ±0.5dBm
-30dBm ±0.5dBm
-40dBm ±0.5dBm
-50dBm ±0.5dBm
-60dBm ±0.5dBm
-70dBm ±0.5dBm
-80dBm ±0.5dBm
-10dBm Range
-20dBm Range
-30dBm Range
-40dBm Range
-50dBm Range
-60dBm Range
-70dBm Range
-80dBm Range
40Hz to 1SkHz
0dBm Range
-10dBm Range
-20dBm Range
-30dBm Range
-40dBm Range
-50dBm Range
-60dBm Range
0dBm ±0.2dBm
-10dBm ±0.2dBm
-20dBm ±0.2dBm
-30dBm ±0.2dBm
-40dBm ±0.2dBm
-50dBm ±0.2dBm
-60dBm ±0.2dBm
100Hz to 20kHz
+30dBm Range
+20dBm Range
+10dBm Range
+30dBm 0±0.5dBm
+20dBm ±0.5dBm
+l0dBm ±0.5dBm
100Hz to 15kHz
+30dBm Range
+20dBm Range
+10dBm Range
+30dBm ±0.2dBm
+20dBm ±0.2dBm
+10dBm ±0.2dBm
(2)
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PERFORMANCE CHECK TEST CARD (Cont'd)
RETURN LOSS CHECK
VF/Nm
600 ohms
900 ohms
30Hz to 20kHz
>30dB
CARRIER
600 ohms, 1kHz to 150kHz
>26dB
> 26dB
>30dB
135 ohms, 1kHz to 600kHz
75 ohms, 1kHz to 3MHz
FILTER RESPONSE CHECKS
C-MSG
60Hz
200Hz
500Hz
1kHz
-55.7dBm ±2dBm
-25dBm ±2dBm
-7.5dBm ±1dBm
0dBm (Ref)
2kHz
2.5kHz
4kHz
5kHz
-1.3dBm ±1dBm
-1.4dBm ±2dBm
-14.5dBm ±3dBm
-28.5dBm ±3dBm
3kHz FLAT
60Hz
250Hz
1kHz
0dBm ±1.75dBm
0dBm ±1dBm
0dBm (Ref)
2kHz
2.5kHz
3kHz
-0.5dBm ±1.75dBm
-1.5dBm ±2dBm
-3dBm ±3dBm
15kHz FLAT
60Hz
250Hz
0dBm ±1.75dBm
0dBm ±1dBm
1kHz
0dBm (Ref)
5kHz
10kHz
12.5kHz
0dBm ±1dBm
-0.5dBm ±1.75dBm
-1.5dBm ±2dBm
-3dBm ±3dBm
15kHz
PROGRAM
200Hz
-17.3dBm ±2dBm
-6.6dBm ±1dBm
0dBm (Ref)
500Hz
1kHz
2kHz
4kHz
5kHz
6kHz
8kHz
10kHz
+4.8dBm ±2dBm
+6.5dBm ±2dBm
+6.5dBm ±2dBm
+6.4dBm ±3dBm
+4dBm ±3dBm
-8.5dBm ±4dBm
BRIDGING LOSS CHECK
VF/Nm 900 BAL, 1kHz
VF/Nm 600 BAL, 1kHz
CARRIER 600 BAL, 10kHz
INPUT BALANCE CHECK
VF/Nm 600 BAL
60Hz
0.3dBm
<0.3dBm
<.05dBm
>80dB
>70dB
>50dB
6kHz
20kHz
CARRIER 600 BAL
1kHz to 10kHz
1kHz to 100kHz
1kHz to 600kHz
>70dB
>60dB
>40dB
(3)
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Model 3555B
Section VI
SECTION VI
REPLACEABLE PARTS
c. Typical manufacturer of the part in a five-
manufacturers.)
d. Manufacturer's part number.
Miscellaneous parts are listed at the end of
6-1.
6-2.
INTRODUCTION.
This section contains information for ordering
order of their reference designators and indicates the
description, -hp- part number of each part, together with
any applicable notes, and provides the following:
a. Total quantity used in the instrument (TQ
column). The total quantity of a part is
given the first time the part number
appears.
6-3.
6-4.
6-5.
ORDERING INFORMATION.
To order a part, note the manufacturer's part
reference that number in the cross-reference index
MFR PART NO. and the manufacturer's identification
b. Description of the part.
abbreviations below.)
(See list of
ABBREVIATIONS
Ag....................................................silver
Al..............................................aluminum
A..............................................ampere(s)
Au......................................................gold
ID.................................... inside diameter
impg.....................................impregnated
incd.....................................incandescent
ins...................................... insulation(ed)
ns............nanosecond(s) = 10-9 seconds
nar................. not separately replaceable
SPDT ........single-pole double-throw
SPST...........single-pole singe-throw
W.................................................. ohm(s)
obd...........................order by description
OD ................................outside diameter
Ta........................................tantalum
TC ............... temperature coefficient
TiO2......................... titanium dioxide
tog ...........................................toggle
tol .......................................tolerance
trim.......................................trimmer
TSTR ................................ transistor
C................................................capacitor
cer...............................................ceramic
coef .........................................coefficient
com ........................................... common
comp ....................................composition
conn .......................................connection
kW........................ kilohm(s) = 10+3 ohms
kHz ..........................kilohertz = 10+3hertz
P ...................................................... peak
Pa .................................... picoampere(s)
pc.......................................printed circuit
pF.................................picofarad(s) 10-12
farads
piv ...........................peak inverse voltage
p/o..................................................part of
pos..........................................position(s)
poly ....................................... polysterene
pot...........................................potiometer
p-p.......................................peak-to-peak
ppm................................parts per million
prec..................... precision (temperature
........................coefficient, long term sta-
............................ bility, and/or tolerance)
L.................................................. inductor
lin...........................................linear taper
log.................................logarithmic taper
V..............................................volt(s)
vacw.................... alternating current
working voltage
var ........................................variable
vdcw.. direct current working voltage
dep ...........................................deposited
DPDT ..............double-pole double-throw
DPST ...............double-pole single-throw
mA.......... milliampere(s) = 10-3 amperes
MHz .................... megahertz = 10+6 hertz
mW ...................megohm(s) = 10+6 ohms
met film.................................... metal film
mfr ......................................manufacturer
ms..........................................millisecond
mtg ........................................... mounting
mV........................millivolt(s) = 10-3 volts
mF ...................................... microfarad(s)
ms....................................microsecond(s)
mV .......................microvolt(s) = 10-6 volts
my.................................................Mylar®
elect ....................................... electrolytic
encap .................................encapsulated
W ...........................................watt(s)
w/................................................with
wiv...............working inverse voltage
w/o.........................................without
ww................................... wirewound
F..................................................farad(s)
FET .........................field effect transistor
fxd.....................................................fixed
.................................................................
GaAs.............................gallium arsenide
GHz.......................gigahertz = 10+9 hertz
gd .............................................guard(ed)
Ge ......................................... germanium
grd..........................................ground(ed)
R ..................................................resistor
Rh ...............................................rhodium
rms..............................root-mean-square
rot....................................................rotary
*.............. optimum value selected at
factory, average value
shown (part may be omitted)
** .............. no standard type number
assigned (selected or
nA ..........nanoampere(s) = 10-9 amperes
NC ..................................normally closed
Ne.................................................... neon
NO.................................... normally open
NPO...................... negative positive zero
..................(zero temperature coefficient)
Se ............................................. selenium
sect..........................................section(s)
Si....................................................silicon
sl ...................................................... slide
special type
H.............................................. henry(ies)
Hg............................................... mercury
Hz................. hertz (cycle(s) per second)
® Dupont de Nemours
DECMAL MULTIPLIERS
Multiplier Prefix
centi
Prefix
tear
giga
mega
kilo
hecto
deka
deci
Symbols
Symbols
Multiplier
10-2
T
G
1012
c
m
m
n
p
f
109
106
103
102
10
milli
10-3
M or Meg
K or k
micro
nano
pico
10-6
10-9
h
da
d
10-12
10-15
10-18
femto
atto
10-1
a
DESIGNATORS
A............................................... assembly
B..................................................... motor
BT .................................................battery
C................................................capacitor
CT ...................................................diode
DL............................................. delay line
DS ....................................................lamp
E...............................misc electronic part
F........................................................fuse
FL ..................................................... filter
HR .................................................heater
IC.................................. integrated circuit
J.........................................................jack
K ...................................................... relay
L.................................................. inductor
M.....................................................meter
MP ................................. mechanical part
P ....................................................... plug
Q...............................................transistor
QCR................................transistor-diode
R ..................................................resistor
RT............................................thermistor
S ....................................................switch
T ........................................... transformer
TB.....................................terminal board
TC......................................thermocouple
TP............................................. test point
TS ............................... terminal strip
V.................vacuum tube, neon bulb
photocell, etc.
W .............................................cable
X.............................................socket
XDS................................ lampholder
XF.....................................fuseholder
Y.............................................crystal
Z...........................................network
6-1
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Section VI
Model 3555B
Table 6-1. Replaceable Parts
REFERENCE
DESIGNATOR
-hp-
PART NO.
TQ
DESCRIPTION
MFR.
MFR. PART NO.
A1
03555-66507
1
PC Board Ass'y: function
-hp-
C1
C2.C3
C4
C5*
C6
0170-0055
0180-0089
0121-4105
0160-0205
0160-2206
1
2
3
2
1
C: fxd mylar 0.1uF +/-20% 200 vdcw
C: fxd Al elect 10uF +50% -10% 150 vdcw
C: var 9-35pF
56289
56289
72982
72136
72136
192P10402-PTS
30D106F150DD2-DSM
538-00694D
RDM15C100J5S
RDM15F161J3C
C: fxd mica 10pF +/-5%
C: fxd mica 160pF +/-5%
C7
0121-0105
0140-0204
0140-0193
0160-0763
C: var 9-35pF
72982
72136
72136
14655
53830694D
DM15E470J0500W1CR
RDM15E82OJ3C
RDM15C050K5S
MFF-1/2-T-1
CB2211
C8*
C9*
C10
1
1
1
C: fxd mica 47pF +/-5%
C: fxd mica 82pF +/-5%
C: fxd mica 5pF 10%
obd
R1
0698-0090
0811-2846
0684-2211
0811-2847
0698-3499
2
2
3
2
2
R: fxd met flm 464 ohms +/-1% 1/2W
R: fxd ww 300 ohms +/-1% 1/2W
R: fxd comp 220 ohms +/-10% 1/4W
R: fxd ww 67.5 ohms +/-1% 1/2W
R: fxd met flm 40.2 kilohms +/-1% 1/8W
91637
-hp-
01121
-hp-
91637
obd
R2
R3
R4
R5,R6
MF-1/10-32
obd
R7
0698-4508
0698-4467
0698-0090
0811-2846
0684-2211
1
1
R: fxd met flm 78.7 kilohms +/-1% 1/8W
R: fxd met flm 1.05 kilohms +/-1% 1/8W
R: fxd met flm 464 ohms +/-1% 1/2W
R: fxd ww 300 ohms +/-1% 1/2W
14674
91637
91637
-hp-
C4
obd
obd
obd
R8
MF-1/10-32
MFF-1/2-T-1
R9
R10
R11
R: fxd comp 220 ohms +/-10% 1/4W
01121
CB2211
CB4711
R12*
R13
R14*
R15
R16
0684-4711
0811-2794
0684-2211
0757-0472
0811-2847
1
1
R: fxd comp 470 ohms +/-10% 1/4W
R: fxd prec ww 25 kilohms 5%
R: fxd comp 220 ohms +/-10% 1/4W
R: fxd met flm 200 kilohms +/-1% 1/8W
R: fxd ww 67.5 ohms +/-1% 1/2W
01121
-hp-
01121
75042
-hp-
CB2211
CEA
3
obd
obd
R17
S1
0683-1505
3100-1793
1
1
R: fxd 15 ohms +/-5% 1/4W
Switch Ass'y: pushbutton
01121
71590
CB1505
1332
T1
T2
9100-1458
9100-1460
1
1
Transformer: carrier frequency
Transformer: audio
-hp-
-hp-
W1
03555-61616
1
Cable Ass'y: function
-hp-
A2
03555-66509
1
PC Board Ass'y: range switch
-hp-
C1
C2
C3
C4
C5
0121-0128
0160-0196
0160-2130
0121-0128
0160-0196
4
2
4
C: var 1.4-9.2pF air trim
C: fxd mica 24pF +/-5%
C: fxd mica 865pF +/-1% 100 vdcw
C: var 1.49.2pF air trim
74970
72136
72136
74970
72136
189-503-5
RDM15C240J3S
RDM15F(865)F1C
189-503-5
C: fxd mica 24pF +/-5%
RDM15C240J3S
C6
0160-2130
0121-0128
0160-2307
0160-3482
0160-3586
C: fxd mica 865pF +/-1% 100 vdcw
C: var 1.4-9.2pF air trim
72136
74970
00853
14655
72136
RDM15F(865)F1C
189-503-5
RDM15E470J3C
RDM15F431F3C
RDM15E4300D3C
C7
†C8
†C9
†C10
1
1
1
C: fxd mica 47pF 5%
C: fxd mica 430pF 1% 300 vdcw
C: fxd mica 43pF 300 vdcw
†C11
C12
0160-3083
0121-0128
1
C: fxd mica 62pF 1% 500 V
C: var 1.4-9.2pF air trim
72136
74970
RDM15D620F5C
189-503-5
R1
R2
R3
R4
R5
0698-7330
0698-7329
0684-2701
0698-7330
0698-7329
2
2
2
R: fxd flm 96.84 kilohms +/-0.1% 1/8W
R: fxd met firm 3.266 kilohms +/-0.1% 1/8W
R: fxd comp 27 ohms +1-10% 1/4W
R: fxd flm 96.84 kilohms +/0.1% 1/8W
R: fxd met firm 3.266 kilohms +/-0.1% 1/8W
91637
91637
01121
91637
91637
CMF-1/10-32
CMF-1/10-32
CB2701
CMF-1/10-32
CMF-1/10-32
obd
obd
obd
obd
6-2
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Model 3555B
Section VI
Table 6-1. Replaceable Parts (Cont'd)
REFERENCE
DESIGNATOR
-hp-
PART NO.
TQ
DESCRIPTION
MFR.
MFR. PART NO.
A2 (Cont'd)
R6
R7
R8
R9
R10
0683-1805
0698-4342
0698-4339
0698-5095
0698-7328
1
1
1
1
1
R: fxd comp 18 ohms +/-5% 1/4W
01121
91637
91637
01121
91637
CB1805
R: fxd met flm 90 kilohms +/-0.1% 1/8W
R: fxd met flm 11.11 kilohms +/-0.1% 1/8W'
R: fxd carbon comp 12 ohms +/-10% 1/2W
R: fxd met flm 68.38 kilohms +/-0.1% 1/8W
MF-1/10-32
MF-1/10-32
CB1201
obd
obd
MF-1/10-32
obd
obd
R11
R12
R13
R14
0698-7331
1
R: met flm 46.28 kilohms +/-0.1% 1/8W
Not assigned
R: fxd met flm 2.37 kilohms +/-1% 1/8W
R: fxd met flm 11.8 kilohms +/-1% 1/8W
91637
MF-1/10-32
0698-3150
0698-3264
1
1
91637
14674
MF-1/1O 2
C4
obd
obd
S1
3100-1791
1
Switch: rotary range
76854
1332
obd
A3
03555-66508
1
Board Ass'y: amplifier
-hp-
C1*
C2
C3
C4
C5
0160-0763
0180-0197
0180-1746
0160-2964
0160-0205
2
5
4
6
C: fxd mica 5pF +/-10%
72136
56289
56289
72982
72136
RDM15COFOKSS
C: fxd Ta 2.2uF +/-10% 20 vdcw
C: fxd Ta elect 15uF +/-10% 20 vdcw
C: fxd cer 0.01uF +80% -20% 25 vdcw
C: fxd mica 10pF +/-5%
150D225X902oA2-DYS
150D156X9020B2-DYS
5835000.Y5UO-10 32
RDM15C100J58S
C6,C7
C8
0160-0378
0121-0105
0140-0196
0180-0228
0180-0106
2
1
C: fxd mica 27pF +/-5%
C: var 9-35pF
C: fxd mica 150pF +/-5%
C: fxd Ta elect 22uF +/-10% 15 vdcw
C: fxd Ta 60uF +/-20% 6 vdcw
72136
72982
72136
37942
56289
RDM15E27OJ5S
538400694D
RDM15F151J3C
TAS226K015P1C
90803
C9
C10
C11
10
1
C12 thru C14
C15*
0160-2964
0180-0228
0180-0393
0160-2964
C: fxd cer 0.01uF +80% -20% 25 vdcw
C: fxd Ta elect 22uF +/-10% 15 vdcw
C: fxd Ta elect 39uF +/-10% -10 vdcw
C: fxd cer 0.01uF +80% -20% 25 vdcw
Not assigned
72982
37942
37942
72982
5835000)Y5U-1032
TAS226K015P1C
TAS396KO10PIC
5835000.Y5UO-1032
C16
3
C17
C18
C19
C20
C21
C22
C23
0180-0197
0160-0763
0180-1702
0160-2964
0180-0197
C: fxd Ta 2.2uF +/-10% 20 vdcw
C: fxd mica 5pF +/-10%
C: fxd Ta elect 180uF +/-20% 6 vdcw
C: fxd cer 0.01uF +80% -20% 25 vdcw
C: fxd Ta 2.2uF +/-10% 20 vdcw
56289
72136
37942
72982
56289
150D225X9020A2-DYS
RDM15C050K5SS
1
obd
5835-000-Y5U0-1032
150D225X9020A2-DYS
C24
C25
C26
C27
C28
0180-0137
0180-0197
0150-0011
0180-0393
0180-0196
1
1
1
1
C: fxd Ta 100uF +/-20% 10 vdcw
C: fxd Ta 2.2uF +/-10% 20 vdcw
C: fxd TiO2 1.5pF +/-20% 500 vdcw
C: fxd Ta elect 39uF +/-10% -10 vdcw
C: fxd Ta 56uF +/-10% 15 vdcw
56289
56289
78488
37942
37942
150D107X0010R2-DYS
150D225X9020A2-DYS
Type GA
obd
TAS396KO10P1C
TAS566K015P F
C29
C30 thru C32
C33
C34
C35 thru C37
0180-0374
0180-0228
0180-0197
0180-1794
0180-1746
C: fxd Ta elect 1OuF +/-10% 20 vdcw
C: fxd Ta elect 22uF +/-10% 15 vdcw
C: fxd Ta 2.2uF +/-10% 20 vdcw
C; fxd Ta elect 22uF +/-10% 35 vdcw
C: fxd Ta elect 15uF +/-10% 20 vdcw
37942
37942
56289
56289
56289
TAS106K020F1C
TAS226K015PlC
150D225X9020A2-DYS
150D226X9035R2-DYS
150D156X9020B2-DYS
1
CR1,CR2
CR3,CR4
CR5 thru CR7
CR8
1901-0376
1902-3030
1901-0040
1902-0761
1902-3030
2
Diode: Si 35 wiv 2pF
Diode: zener 3.01V +/-5% 400mW 20mA
Diode: Si 30 wiv 2pF 30mA 2ns
Diode: zener 6.2V +/-5% 400mW 7.5mA
Diode: zener 3.01V +/-5% 400mW 20mA
07933
04713
07263
04713
04713
RD5288
4
SZ10939-32
FDG1O88
Type 1N821
SZ1Q939-32
11
3
CR9
CR10
1901-0040
1902-3030
1901-0040
1902-0761
1901-0040
Diode: Si 30 wiv 2pF 30mA 2ns
Diode: zener 3.01V +/-5% 400mW 20mA
Diode: Si 30 wiv 2pF 30mA 2ns
Diode: zener 6.2V +/-5% 400mW 7.5mA
Diode: Si 30 wiv 2pF 30mA 2ns
07263
04713
07263
04713
07263
FDG1OB8
SZ10939-32
FDG1088
Type 1N821
FDG1088
CR11
CR12,CR13
CR14
CR15,CR16
CR17
CR18,CR19
1901-0025
1901-0040
7
Diode: Si 100 wiv 12pF 10mA
Diode: Si 30 wiv 2pF 30mA 2ns
24446
07263
SS410
FDG10O88
6-3
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Section VI
Model 3555B
Table 6-1. Replaceable Parts (Cont'd)
REFERENCE
DESIGNATOR
-hp-
PART NO.
TQ
DESCRIPTION
MFR.
MFR. PART NO.
A3 (Cont'd)
CR20
CR21
1902-1275
1901 0040
Diode: zener 6.2V +/-5% 400mW 7.5mA
Diode: Si 30 wiv 2pF 30mA 2ns
04713
07263
Type 1N821
FDG1088
K1 thru K3
0490-0780
0490-0778
9100-1637
3
3
1
Relay Ass'y: reed
Reeds
-hp-
95348
82142
MR5830
L1
Inductor: fxd 120uH +/-5%
15-1315-14J
Q1
Q2, Q3
Q4
Q5 thru Q8
Q9
Q10
1853-0086
1853-0036
1854-0215
1853-0036
1854-0215
1853-0036
7
9
3
TSTR: Si PNP 2N5087
TSTR: Si PNP 2N3906
TSTR: Si NPN 2N3904
TSTR: Si PNP 2N3906
TSTR: Si NPN 2N3904
TSTR: Si PNP 2N3906
04713
04713
04713
04713
04713
04713
SPS-3322
SPS-3612
SPS-3611
SPS-3612
SPS-3611
SPS-3612
Q11
Q12
Q13
Q14
Q15
1855-0057
1853-0036
1854-0092
1853-0049
1854-0215
1
TSTR: Si FET N channel Type A
TSTR: Si PNP 2N3906
TSTR: NPN 2N3563
04713
04713
04713
04713
04713
SS-3651
SPS-3612
MPS-3563
-hp-
2
2
TSTR: Si PNP
TSTR: Si NPN 2N3904
SPS-3611
Q16
1853-4049
1854-0401
1853-0235
1854-0022
1853-0235
TSTR: Si PNP
04713
04713
12040
01295
12040
-hp-
Q17
1
3
1
TSTR: NPN
-hp-
Q18,Q19
Q20
Q21
TSTR: Si PNP 2N3547
TSTR: NPN
TSTR: Si PNP 2N3547
NS62048
SG1294
NS62048
Q22
1853-0037
1
TSTR: Si PNP
04713
2N2904A
R1
0757-0334
0698-4521
0698-4533
0684-4731
0684-1221
0684-1011
0684-2241
0684-4721
0684-1011
0698-7375
1
2
1
2
2
5
2
3
R: fxd met flm 301 ohms +/-1% 1/4W
R: fxd met flm 154 kilohms +/-1% 1/8W
R: fxd met flm 294 kilohms +/-1% 1/8W
R: fxd comp 47 kilohms +/-10% 1/4W
R: fxd comp 1.2 kilohms +/-10% 1/4W
R: fxd comp 100 ohms +/-10% 1/4W
R: fxd comp 220 kilohms +/-10% 1/4W
R: fxd comp 4700 ohms +/-10% 1/4W
R: fxd comp 100 ohms +/-10% 1/4W
R: fxd met flm 28.64 kilohms +/-0.1% 1/8W
91637
14674
14674
01121
01121
01121
01121
01121
01121
91637
MF-1/8-44
C4
obd
obd
obd
R2
R3
C4
R4
CB4731
CB1221
CB1011
C82241
CB4721
CB1011
CMF-1/10-32
R5
R6
R7,R8
R9
R10
R11
3
obd
obd
obd
R12
R13,R14
R15
0684-1011
0757-0273
2100-2829
R: fxd comp 100 ohms +/-10% 1/4W
R: fxd met flm 3.01 kilohms +/-1% 1/8W
R: var carbon comp 500 ohms +/-30%
1/4W 4 sec type V
R: fxd met flm 590 ohms +/-1% 1/8W
R: fxd comp l00 ohms +/-10% 1/4W
01121
91637
CB1011
MF-1/10-32
2
1
71590
14674
01121
Type E8-83716
C4
CB1011
R16
R17
0698-4458
0684-1011
1
R18
R19
R20
R21
R22
0684-1041
0698-3154
2100-2829
0698-3155
0698-4405
1
1
R: fxd comp 100 kilohms +/-10% 1/4W
R: fxd met flm 4.22 kilohms +/-1% 1/8W
R: var carbon comp 5 kilohms +/-30%
R: fxd metflm 4.64 kilohms +/-1% 1/8W
R: fxd met flm 107 ohms +/-1% 1i8W
01121
91637
71590
91637
14674
CB1041
MF-1/10-32
Type E8-83716
MF-1/10-32
C4
obd
1
1
obd
obd
R23
0684-2221
2100-2829
0698-4014
2100-2829
0698-4521
1
1
R: fxd comp 2200 ohms +/-10% 1/4W
R: var carbon comp 500 ohms +/-30%
R: fxd met flm 787 ohms +/-1% 1/8W
R: var carbon comp 500 ohms +/-30%
R: fxd met flm 154 kilohms +/-1% 1/8W
Not assigned
R: fxd comp 330 kilohms +/-10% 1/4W
R: fxd comp 150 kilohms +/-10% 1/4W
R: fxd comp 100 ohms +/-10% 1/4W
R: fxd comp 1.2 kilohms +/-10% 1/4W
01121
71590
14674
71590
14674
CB2221
Type E8-83716
C4
Type E883716
C4
R24
R25
obd
obd
R26
R27
R28,R29
R30
0684-3341
0684-1541
0684-1011
0684-1221
1
3
01121
01121
01121
01121
CB3341
CB1541
CB1011
CB1221
R31
R32
R33
R34
R35,R36
R37
R38
R39
0684-1021
0684-1541
0684-4721
0698-4454
0684-3921
6
R: fxd comp 1O000 ohms +/-10% 1/4W
R: fxd comp 150 kilohms +/-10% 1/4W
R: fxd comp 4700 ohms +/-10% 114W
R: fxd met flm 523 ohms +/-1% 1/8W
R: fxd comp 3900 ohms +/-10% 1/4W
01121
01121
01121
91637
01121
C81021
CB1541
C84721
MF-1/10-32
CB3921
1
3
obd
6-4
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Model 3555B
Section VI
Table 6-1. Replaceable Parts (Cont'd)
REFERENCE
DESIGNATOR
-hp-
PART NO.
TQ
DESCRIPTION
MFR.
MFR. PART NO.
A3 (Cont'd)
R40
R41,R42
R43
R44
R45
0684 4721
0698-3382
2100-1770
0698-3223
0684-2231
R: fxd comp 4700 ohms +/-10% 1/4W
R: fxd met flm 5.49 kilohms +/-1% 1/8W
R: var ww 00 ohm +/-10O% 1/2W trimmer
R: fxd met flm 1.24 kilohms +/-1% 1/8W
R: fxd comp 22 kilohms +/-10% 1/4W
01121
91637
80294
91637
01121
CB4721
2
1
1
3
MF-1/10-32
3-365P-E88-101
MF-1/10-32
CB2231
obd
obd
R46*
R47
R48
R49
R50
0684-3921
0684-8211
0684-2231
0757-4442
0684-1031
R: fxd comp 3900 ohms +/-10% 1/4W
R: fxd comp 820 ohms +/-10% 1/4W
R: fxd comp 22 kilohms +/-10% 1/4W
R: fxd met flm 10 kilohms +/-1% 1/8W
R: fxd comp 10 kilohm +/-10% 1/4W
01121
01121
01121
91637
01121
CB3921
CB8211
CB2231
MF-1/10-32
CB1031
2
3
2
obd
R51
0084-8211
0767-0280
0684-1211
0757-0442
R: fxd comp 820 ohm +/-10% 1/4W
R: fxd met flm 1 kilohm +/-1% 1/8W
R: fxd comp 120 ohm +/-10% 1/4W
R: fxd met flm 10 kilohms +/-1% 1/8W
Not assigned
01121
91637
01121
91637
CB8211
R52
CMF-1/10-32
CB1211
obd
obd
R53,R54
R55
R56 thru R58
2
MF-1/10-32
R59
R60
R61
R62
R63
0757-4468
0684-3331
0684-1001
0684-3921
0684-1031
1
1
3
R: fxd met flm 130 kilohm +/-1% 1/8W
R: fxd comp 33 kilohms +/-106 1/4W
R: fxd comp 10 ohm +/-10O% 1/4W
R: fxd comp 3900 ohms +/-10% 1/4W
R: fxd comp 10 kilohms +/-10O 1/4W
14674
01121
01121
01121
01121
C4
obd
CB3331
CB1001
CB3921
CB1031
R64
R65 thru R67
R68
R69
R70,R71
0684-2231
0684-1021
0698-4503
0698-4491
06841001
R: fxd comp 22 kilohms +/-10% 1/4W
R: fxd comp 1000 ohms +/-10% 1/4W
R: fxd met flm 66.5 kilohms +/-1% 1/8W
R: fxd met flm 30.9 kilohms +/-1% 1/8W
R: fxd comp 10 ohm +/-10% 1/4W
01121
01121
91637
91637
01121
CB2231
CB1021
1
1
MF-1/10-32
MF-1/10-32
CBI001
obd
obd
R72*
0684-2701
0684-1021
0684-8221
R: fxd comp 27 ohm +/-10% 1/4W
R: fxd comp 1000 ohm +/-10% 1/4W
R: fxd comp 8200 ohm +/-10% 1/4W
01121
01121
01121
CB2701
CB1021
CB8221
R73
R74*,R75*
2
XA1
W1
1251-1941
0355-61616
1
1
Connector: PC 6 pin
Cable
71785
-hp-
252-06-30-310
A4
03555-66506
1
PC Board Ass'y: filter
-hp-
C1
0140-0177
0180-0291
0160-2130
0140-0203
0180-0228
1
4
C: fxd mica 400pF +/-1%
72136
56289
72136
72136
37942
RDM15F3C
C2
C: fxd Ta elect 1uF +/-10% 35 vdcw
C: fxd mice 865pF +/-1% 100 vdcw
C: fxd mica 30pF +/-5%
150D105X9035A2-DYS
RDM15F(865)F1C
RDM15F421F3C
C3,C4
C5
C6
5
C: fxd elect 22uF +/-10% 15 vdcw
TAS226K015PlC
C7
0140-0163
0160-3024
0140-0203
0160-3024
0180-0228
6
4
C: fxd mice 4751pF +/-1% 300 vdcw
C: fxd mica 1700pF +/-1% 100 vdcw
C: fxd mice 30pF +/-5%
C: fxd mice 1700pF +/-1% 100 vdcw
C: fxd Ta elect 22uF +/-10% 15 vdcw
72136
72136
72138
72138
37942
RDM20F(4751)F3S
RDM19F 72F1S
RDM15F421F3C
RDM19F172F1S
TAS226KOlPlC
C8
C9
C10
C11
C12
C13 thru C15
C16
C17
C18
0140-0163
C: fxd mica 4751pF +/-1% 300 vdcw
Not assigned
C: fxd mice 1700pF +/-1% 100 vdcw
C: fxd mica 30pF +/-5%
C: fxd mica 1700pF +/-1% 100 vdcw
72136
RDM20F(4751)F3S
0160-3024
0140-0203
0160-3024
72136
72136
72136
RDM19F172F1S
RDM15F421F3C
RDM19F172F1S
C19
C20,C21
C22
C23
C24
0180-0228
0180-0291
C: fxd Ta elect 22uF +/-10% 15 vdcw
C: fxd Ta elect 1uF +/-10% 35 vdcw
Not assigned
C: fxd Ta 2.2uF +/-10% 20 vdcw
C: fxd mica 4751pF +/-1% 300 vdcw
37942
56289
TAS226KO15P1C
15OD105X9035A2-DYS
0180-0197
0140-0163
56289
72136
150D225X9020A2-DYS
RDM20F(4751)F3S
C25
0140-0203
0140-0163
0180-0228
0140-0163
0140-0203
C: fxd mice 30pF +I-5%
72136
72136
37942
72136
72136
RDM15F421F3C
RDM20F(4751)F3S
TAS226K01SPIC
RDM20F(4751)F3S
RDM15F421F3C
C26
C: fxd mice 4751pF +/-1% 300 vdcw
C: fxd Ta elect 22uF +/-10% 15 vdcw
C: fxd mica 4751pF +/-1% 300 vdcw
C: fxd mice 30pF +/-5%
C27
C28,C29
C30
6-5
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Section VI
Model 3555B
Table 6-1. Replaceable Parts (Cont'd)
REFERENCE
DESIGNATOR
-hp-
PART NO.
TQ
DESCRIPTION
MFR.
MFR. PART NO.
A4 (Cont'd)
C31
C32
C33
0180-0228
0180-0291
0180-0387
C: fxd Ta elect 22uF +/-10% 15 vdcw
C: fxd Ta elect 1uF +/-10% 35 vdcw
C: fxd Ta elect 47uF +/-5% 20 vdcw
37942
56289
37942
TAS226K015P1C
150D105X9035A2-DYS
TAS476J020P1F
1
CR1 thru CR5
1901-0026
Diode: Si 100 wiv 12pF 100mA
24446
SS410
Q1,Q2
Q3
Q4,Q5
Q6
Q7,Q8
1854-0071
1853-0086
1854-0071
1853-0086
1854-0071
16
6
TSTR: Si NPN 2N3391
TSTR: Si PNP 2N5087
TSTR: Si NPN 2N3391
TSTR: Si PNP 2N5087
TSTR: Si NPN 2N3391
01296
04713
01296
04713
01296
SKA1124
SPS-3322
SKA1124
SPS-3322
SKA1124
Q9
1853-0086
1854-0071
1853-0086
1854-0071
1853-0086
TSTR: Si PNP 2N5087
TSTR: Si NPN 2N3391
TSTR: Si PNP 2N50B7
TSTR: Si NPN 2N3391
TSTR: Si PNP 2N5087
04713
01295
04713
01295
04713
SPS-3322
SKA1124
SPS-3322
SKA1124
SPS-3322
Q10 thru Q12
Q13
Q14 thru Q16
Q17
Q18 thru Q20
Q21
Q22
1854-0071
1853-0086
1854-0071
TSTR: Si NPN 2N3391
TSTR: Si PNP 2N5087
TSTR: Si NPN 2N3391
01295
04713
01296
SKA1124
SPS-3322
SKA1124
R1
0757-0450
0038-4412
2100-0406
0698-7373
0698-7374
2
1
1
1
2
R: fxd et flm 22.1 kilohms +/-1% 118W
R: fxd met flm 17.4 kilohms +/-1% 1/8W
R: var carbon comp 5 kilohms +/30% 4 sec
R: fxd met flm 98.941 kilohms +/-0.1% 1/8W
R: fxd met flm 217Jkilohms +/-0.1% 1/8W
75042
91637
71590
91637
91637
CEA
obd
R2
MF-1/10-32
Series 5 Type 70-4
CMF-1/10-32
CMF-1/10-32
obd
R3
R4
R5,R6
obd
obd
R7(A/B/C)
R8
1810-0027
0698-7372
0698-7376
0698-6313
0698-7375
5
1
1
5
R: carbon flm network 2X1OOK 10 kilohms +/-10%
R: fxd met flm 108.94 kilohms +/-0.1% 1/8W
R: fxd met flm 11.397 kilohms +/-0.1% 1/8W
R: fxd met flm 20 kilohms +/-0.1% 118W
56289
91637
91637
91637
91637
178C5
CMF-1/10-32
CMF-1/10-32
CMF-1/10-32
CMF-1/10-32
obd
obd
obd
obd
R9
R10
R11
R: fxd met flm 28.640 kilohms +/-0.1% 1/8W
R12,R13
R14
0757-0476
0684-6821
0604-4731
0698-3557
0698-3519
2
1
R: fxd met flm 301 kilohms +/-1% 1/8W
R: fxd comp 6800 ohms +/-10% 1/4W
R: fxd comp 47 kilohms +/-10% 11/4W
R: fxd met flm 806 ohms +/-1% 1/8W
R: fxd met flm 12.4 kilohms +/-1% 1/8W
14674
01121
01121
14674
91637
C4
obd
CB6821
C84731
C4
R15
R16*
R17
1
1
obd
obd
MF-1/10-32
R18*
0757-0443
1
R: fxd met flm 11 kilohms +/-1% 1/8W
Not assigned
R: fxd met flm 28.640 kilohms +/-0.1% 1/8W
R: carbon flm network 2X100K 10 kilohms +/-10%
R: fxd met flm 24.3 kilohms +/-1% 1/8W
14674
C4
obd
obd
obd
R19
R20
R21(A/B/C)
R22
0698-7375
1810-0027
07570451
91637
56289
14674
CMF-1/10-32
178C5
C4
1
R23
0757-0450
0698-0043
0638-1407
1810-0027
0698-7365
R: fxd met flm 22.1 kilohms +/-1% 1/8W
R: fxd met flm 20 kilohms +/4.1% 1/8W
R: fxd met flm 44.2 kilohms +/-1% 1/8W
R: carbon flm network 2X100K 10 kilohms +/-10%
R: fxd me flm 13.394 kilohms +/-0.1% 1/8W
75042
91637
14674
56289
91637
CEA
CMF-1/10-32
C4
178C5
CMF-1/10-32
obd
obd
obd
R24
R25
R26(A/B/C)
R27
1
1
obd
R28
0038 6043
0757-0465
0684-1051
0757-0280
0757-0442
R: fxd met flm 20 kilohms +/4).1%
R: fxd met flm 100 kilohms +/-1% 1/8W
R: fxd comp 1 megohm +/-10% 1/4W
R: fxd met flm 1 kilohm +/-1% 1/8W
R: fxd met flm 10 kilohm +/-1% 1/8W
91637
14674
01121
91637
91637
CMF-1/1032
C4
obd
obd
R29
1
3
2
R30,R31
R32
R33
C81051
CMF-1/10-32
MF-1/10-32
obd
obd
R34
0757-0448
0757-0472
0698-7366
1810-0027
0638-0043
1
2
R: fxd met flm 1&2 kilohms +/-1% 1/8W
R: fxd met flm 200 kilohms +/-1% 1/8W
R: fxd met flm 109.64.kilohms +/-0.1% 1/8W
R: carbon flm network 2X100K 10 kilohms +/-10%
R: fxd met flm 20 kilohm +/-.1%
91637
75042
91637
56289
91637
MF-1/10-32
CEA
CMF-1/10-32
178C5
CMF-1/10-32
obd
obd
obd
R35,R36
R37,R38
R39(A/B/C)
R40
obd
R41
0698-7367
0698-7369
1810-0027
0698-7368
0698-6943
1
2
R: fxd met flm 78.028 kilohms +-0.1% 1/8W
R: fxd met flm 73803 kilohms +/-0.1% 1/8W
R: carbon flm network 2X100K 10 kilohms +/-10%
R: fxd met flm 36.901 kilohms +/-0.1% 1/8W
R: fxd met flm 20 kilohms +/-0.1%
91637
91637
56289
91637
91637
CMF-1/1032
CMF-1/10-32
178C5
CMF-1/10-32
CMF-1/10-32
obd
obd
R42,R43
R44(A/B/C)
R45
1
obd
obd
R46
6-6
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Model 3555B
Section VI
Table 6-1. Replaceable Parts (Cont'd)
REFERENCE
DESIGNATOR
-hp-
PART NO.
TQ
DESCRIPTION
MFR.
MFR. PART NO.
A4 (Cont'd)
R47
R48
R49
0698-7370
0684-1051
0684-1021
1
R: fxd met flm 17.579 kilohms +/-0.1% 1/8W
R: fxd comp 1 megohm +/-10% 1/4W
R: fxd comp 1000 ohms +/-10% 1/4W
91637
01121
01121
CMF-1/10-32
CB1051
CB1021
obd
03565-60104
1
Chassis Ass’y: power supply
-hp-
CHASSIS MOUNTED COMPONENTS
BT1
1420-0026
1
Battery: 45V
83740
No. 482
C1
C2
C3
C4*
C5
C6
0180-2230
0180-0149
0180-0393
0160-0987
0150-0023
0160-0195
1
1
C: fxd A1 elect 150uF - 10% + 100% 200 vdcw
C: fxd A1 elect 65uF 60 vdcw
C: fxd Ta elect 39uF +/-10% -10 vdcw
C: fxd mica 12pF +/-5%
C: fxd cer 2000oF +/-20% 1000 vdcw
C: fxd cer 1000 pF 20% 250 vac
56289
hp-
37942
72136
56289
56289
62D10046-DFP
TAS396K010P1C
RDM15C120J5S
20C295A2-CDH
19C251A1-CDH
1
1
1
CR1-4
CR6
1901-0025
1901-0040
4
1
Diode: Si 100 wiv 12pF 100mA
Diode: Si 30 V 50 mA
24446
-hp-
SS410
DS1,DS2
F1
2140-0298
2
Neon lamp
74276
A230
2110-0320
1400-0085
2
2
Fuse: 0.15A 125V Slo-Blo
Holder: fuse
71400
75915
MDL 15/100
342004
J1
J2
J3
J4
J5
1251-2357
1251-1900
1200-0163
1251-1144
1251-1143
1
4
1
1
Connector: AC power cord receptacle
Jack: telephone
82389
82389
74868
82389
82389
EAC-301
22A
78PCG5
MT-342B
MT-332B
obd
Receptacle: 5 pin
Jack: telephone
Jack: telephone
J6,J7
J8,J9
J10
1251-0065
1510-0084
1510-0087
1510-0531
1251-0065
4
2
1
1
Jack: telephone
Binding post: red
Binding post Ass'y
Binding post Ass'y
Jack: telephone
82389
-hp-
MT-331
-hp-
J11
-hp-
82389
J12,J13
MT-331
J14
1251-1143
Jack: telephone
82389
MT-332B
J17
J18
1250-1053
1251-1143
1
Jack: coaxial
Jack: telephone
70674
82389
CJ-1010
MT-332B
L1
L2
9100-1390
9140-0088
1
1
Inductor: audio
Inductor: fxd .33uH +%-5% 200mA
-hp-
95262
NB 0.37 PS
M1
1120-0909
1
Meter: log calibrated
-hp-
6-7
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Section VI
Model 3555B
Table 6-1. Replaceable Parts (Cont'd)
REFERENCE
DESIGNATOR
-hp-
PART NO.
TQ
DESCRIPTION
MFR.
-hp-
MFR. PART NO.
CHASSIS MOUNTED COMPONENTS (Cont'd)
03555-67902
1
Power Supply Ass'y
R1
R2
R3
R4
R5
0757-0795
0698-4205
0698-7371
0698-3158
0698-4488
1
1
2
2
1
R: fxd met flm 75 ohms +/-1% 1/2W
91637
91637
91637
91637
91637
MFF-1/2-T-1
MF-1/10-32
CMF-1/10-32
MF-1/10-32
MF-1/10-32
obd
obd
obd
obd
obd
R: fxd met flm 21 kilohms +/-1% 1/8W
R: fxd met flm 20.605 kilohms +/-0.1% 1/8W
R: fxd met flm 23.7 kilohms +/-1% 1/8W
R: fxd met flm 26.7 kilohms +/-1% 1/8W
R6
R7
R8
R9
R10
0698-7371
0757-0290
0698-3158
0698-3245
0757-0455
R: fxd met flm 20.605 kilohms +/-0.1%
R: fxd met flm 6.19 kilohms +/-1% 1/8W
R: fxd met flm 23.7 kilohms +/-1% 1/8W
R: fxd flm 20.5 kilohms +/-1% 1/8W
R: fxd met flm 36.5 kilohms +/-1% 1/8W
91637
14674
91637
14674
14674
CMF-1/10-32
obd
obd
obd
obd
obd
1
C4
MF-1/10-32
Cr
C4
1
1
R11
0698-4434
1
R: fxd met firm 2.32 kilohms +/-1% 1/8W
91637
CMF-1/10-32
1332
obd
obd
S1
3100-1794
03555-61904
3101 0045
3101 -0001
3101-1234
1
1
1
2
1
Switch: lever, input
Switch Ass'y: weighting
Switch: slide
Switch: toggle SPST
Switch: slide DPDT
76854
-hp-
82389
04009
82389
S2
S3
11A-1014A
80994-HB
11A-1242A
S4,S5
S6
T1
9100-1457
1
Transformer: power
-hp-
W1
W2
W3
W4
W5
03555-69503
03555-69504
03555-69502
03555-69505
1
1
1
1
Cable Ass'y
Cable Ass'y
Cable Ass'y
Cable Ass'y
Not assigned
-hp-
-hp-
-hp-
-hp-
W6
W7
03555-69501
03555-61611
1
1
Cable Ass'y
Cable Ass'y: interconnecting and range
-hp-
-hp-
MISCELLANEOUS
0340-0099
0340-0100
0370-0035
0370-0046
0370-0440
4
2
1
2
8
Insulator: binding post
-hp-
-hp-
-hp-
-hp-
-hp-
Insulator: binding post single
Knob: bar w/arrow black
Knob: lever switch, black
Knob: pushbuttons, grey
1390-0137
1390-0186
1400-0062
1400-0076
1520-0001
4
4
1
2
1
Washer: retaining 1/4 turn fastener
Stud: 1/4 turn fastener
Clip: cable
71286
71286
78553
75915
56137
2600-1W
265424
C21891-017-24
101002
Grade X-831
Clip: fuse
Wafer: cap plate mtg 4 lug
4040-0476
5000-7126
5000-7134
5000-7135
5000-7136
5000-7138
5000-7139
5000-7140
5000-7147
8120-1518
1
1
1
1
2
1
1
1
1
1
Insulator: jack
-hp-
-hp-
-hp-
-hp-
-hp-
-hp-
-hp-
-hp-
-hp-
70903
Decal: pushbutton "75 UNBAL"
Decal: pushbutton "135 BAL"
Decal: pushbutton "150 BAL"
Decal: pushbutton "600 BAL"
Decal: pushbutton "HOLD"
Decal: pushbutton "DIAL-BAT"
Decal: pushbutton "NG"
Decal: pushbutton "900 BAL"
Cord Set: power
obd
6-8
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Model 3555B
Section VI
Table 6-1. Replaceable Parts (Cont'd)
REFERENCE
DESIGNATOR
-hp-
PART NO.
TQ
DESCRIPTION
MFR.
MFR. PART NO.
MISCELLANEOUS (Cont'd)
1251-1145
1
2
1
Plug: battery
72825
-hp-
7364
525C-49A
Handle: panel
00236-04105
1390-0186
00741-01212
03555-00206
03555-00204
0340-0732
Cover: battery
-hp-
Stud: fastener cadmium plated steel
Bracket: meter
Panel: front
71286
-hp-
26542-4
2
1
1
1
-hp-
Panel: sub
Insul: Bdg Post
-hp-
-hp-
03555-26510
03555-60604
03555-61204
0355541203
1
1
1
1
Test board: blank
-hp-
-hp-
-hp-
-hp-
Shield Ass'y: amplifier
Retainer Ass'y: cord/headphone
Retainer: headphone
03556-64507
03556-64508
03556-90007
1
1
1
Cover: assembly
-hp-
-hp-
-hp-
Case Assembly
Manual: operating and service
6-9
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TM 11-6625-2779-14&P
TABLE 6-2.
PART NUMBER - NATIONAL STOCK NUMBER
CROSS REFERENCE INDEX
REPLACEMENT
NATIONAL
STOCK
NATIONAL
STOCK
PART
PART
NUMBER
FSCM
NUMBER
NUMBER
FSCM
NUMBER
CB1001
CB1041
CB1541
CB1805
CB2211
CB2221
CB3921
CB4731
CB6821
CB8211
CB8221
EAC-301
MDL15/100
MPS-3563
MT-331
MT-332-B
MT-3428
01121
01121
01121
01121
01121
01121
01121
01121
01121
01121
01121
82389
71400
04713
82389
82389
82389
07933
01295
04713
04713
04713
04713
37942
78488
04713
28480
82389
82389
56289
56289
56289
04713
71286
74868
04009
5905-00-989-8653
5905-00-254-7432
5905-00-726-5345
5905-00-833-0718
5905-00-721-0131
5905-00-726-6433
5905-00-755-0795
5905-00-985-5609
5905-00-721-0671
5905-00-755-0796
5905-00-721-0674
5935-00-233-6728
5920-00-665-3074
5961-00-122-8671
5935-00-201-8993
5935-00-192-4825
5935-00-500-7439
5961-00-222-6128
5961-00-137-4608
5961-00-224-5601
5961-00-137-0966
5961-00-137-0967
5961-00-137-0999
5910-00-816-2474
5910-00-577-1219
5961-00-804-7548
5905-00-489-2050
5930-00-402-6752
5930-00-406-8746
5910-00-850-0830
5910-00-852-2644
5910-00-797-9742
5961-00-941-2056
5325-00-449-3024
5935-00-919-6391
5930-00-929-1970
RCR07G100JS
RCRO7G104JS
RCR07G154JS
RCR07G180JS
RCR07G221JS
RCR07G222JS
RCR07G392JS
RCR07G473JS
RCR07G682JS
RCR07G821JS
RCR07G822JS
81349
81349
81349
81349
81349
81349
81349
81349
81349
81349
81349
5905-00-107-0656
5905-00-110-0388
5905-00-114-5339
5905-00-115-7953
5905-00-135-3973
5905-00-105-7764
5905-00-141-0743
5905-00-141-0717
5905-00-110-7622
5905-00-119-8768
5905-00-104-8358
F03B250V15-100A
JJ086
81349
81349
5920-00-661-0530
5935-00-192-4826
RD5288
RD5288
49956
5961-00-222-6128
SKA1124
SPS3322
SPS3611
SPS3612
SS3651
TAS396K015PIC
TYPE-GA
TYPE-LN821
0698-4521
LLA-1014A
11A-1242A
150D107X0010R2D
19C251AL-CDH
192P10402-PTS
2N2904A
2600-1W
M39003-01-2979
GAO-47PFPORM5PCT 78488
JAN1N821
81349
5910-00-192-7180
5910-00-834-9437
5961-00-866-5454
81349
192P10452
78PCG5
56289
02660
5910-00-984-2845
5935-00-919-6391
78PCG5
80994-HB
6-10
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6-11
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CODE LIST OF MANUFACTURERS (Continued)
6-13
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Model 3555B
Section VII
SECTION VII
CIRCUIT DIAGRAMS
should be used in conjunction with the troubleshooting
7-1.
INTRODUCTION.
7-2.
This section of the Manual contains circuit
7-5.
SCHEMATIC DIAGRAMS.
diagrams for the Model 3555B Transmission and Noise
dc voltage levels which should also aid in locating faulty
components.
7-6.
the Model 3555B. Components marked with an asterisk
are those that are critical in value. The value of these
components may vary slightly from one set to another
due to variations in transistor Beta etc, and the values
shown on the schematic are average.
7-3.
FUNCTIONAL BLOCK DIAGRAM.
7-4.
7-7.
schematics
troubleshooting the set.
voltages a high input impedance voltmeter (1 megohm
or greater) should be used to prevent circuit loading.
Voltage levels have been included on the
which should greatly assist in
When measuring these
3555B serves the dual purpose of showing how various
circuits are arranged to form the set and at the same
time gives voltages and adjustments for use in
troubleshooting the set. This functional block diagram
REFERENCE DESIGNATIONS
7-1
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Section VII
Model 3555B
7-2
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APPENDIX A
REFERENCES
DA Pam 310-4
Index of Technical Manuals, Technical Bulletins, Supply Manuals (Types 7, 8, and 9), Supply
Bulletins and Lubrication Orders.
DA Pam 310-7
US Army Equipment Index of Modification Work Orders.
TM 11-6625-320-12
Operator’s and Organizational Maintenance Manual: Voltmeters ME-30A/U, and voltmeters,
Electronic, ME-30B/U, ME-30C/U and ME30E/U.
TM 11-6625-683-15
TM 11-6625-2953-14
Operator’s Organizational, Direct Support, General Support and Depot Maintenance Manual:
Signal Generator AN/URM-127 (NSN 6625-00-783-5965).
Operator’s, Organizational, Direct Support, and General Support Maintenance Manual:
Multimeter AN/USM-451 (NSN 6625-01-060-6804).
TM 38-750
The Army Maintenance Management System (TAMMS).
TM 740-90-1
TM 750-244-2
Administrative Storage of Equipment.
Procedures for Destruction of Electronics Materiel to Prevent Enemy Use (Electronics
Command).
A-1
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APPENDIX B
MAINTENANCE ALLOCATION
Section I. INTRODUCTION
j.
Overhaul.
That maintenance effort
B-1.
General
(service/action) necessary to restore an item to a
completely serviceable/operational condition as
This appendix provides a summary of the maintenance
operations for TA-885/U. It authorizes categories of
maintenance for specific maintenance functions on
repairable items and components and the tools and
prescribed by maintenance standards (i.e., DMWR) in
appropriate technical publications. Overhaul is normally
the highest degree of maintenance performed by the
Army. Overhaul does not normally return an item to like
new condition.
equipment required to perform each function.
This
appendix may be used as an aid in planning maintenance
operations.
k. Rebuild. Consists of those services/actions
necessary for the restoration of serviceable equipment to
B-2.
Maintenance Function
a
like new condition in accordance with original
Maintenance function will be limited to and defined as
follows:
a. Inspect. To determine the serviceability of
an item by comparing its physical, mechanical, and/or
manufacturing standards. Rebuild is the highest degree
of materiel maintenance applied to Army equipment. The
rebuild operation includes the act of returning to zero
those age measurements (hours, miles, etc.) considered
in classifying Army equipments/components.
electrical characteristics with
through examination.
established standards
B-3.
Column Entries
a. Column 1, Group Number. Column 1 lists
b. Test. To verify serviceability and to detect
incipient failure by measuring the mechanical or electrical
characteristics of an item and comparing those
characteristics with prescribed standards.
c. Service. Operations required periodically to
keep an item in proper operating condition, i.e., to clean
(decontaminate), to preserve, to drain, to paint, or to
replenish fuel, lubricants, hydraulic fluids, or compressed
air supplies.
group numbers, the purpose of which is to identify
components, assemblies, subassemblies, and modules
with the next higher assembly.
b. Column 2, Component/Assembly. Column 2
contains the noun names of components, assemblies,
subassemblies, and modules for which maintenance is
authorized.
c. Column 3, Maintenance Functions. Column
3 lists the functions to be performed on the item listed in
column 2. When items are listed without maintenance
functions, it is solely for purpose of having the group
numbers in the MAC and RPSTL coincide.
d. Adjust. To maintain, within prescribed limits,
by bringing into proper or exact position, or by setting the
operating characteristics to the specified parameters.
e. Align. To adjust specified variable elements
of an item to bring about optimum or desired
performance.
d. Column 4, Maintenance Category. Column 4
specifies, by the listing of a "work time" figure in the
appropriate subcolumn(s), the lowest level of
maintenance authorized to perform the function listed in
column 3. This figure represents the active time required
to perform that maintenance function at the indicated
category of maintenance. If the number or complexity of
the tasks within the listed maintenance function vary at
different maintenance categories, appropriate "work time"
figures will be shown for each category. The number of
taskhours specified by the "work time" figure represents
the average time required to restore an item (assembly,
subassembly, component, module, end item or system) to
a serviceable condition under typical field operating
f.
Calibrate.
To determine and cause
corrections to be made or to be adjusted on instruments
or test measuring and diagnostic equipments used in
precision measurement. Consists of comparisons of two
instruments, one of which is a certified standard of known
accuracy, to detect and adjust any discrepancy in the
accuracy of the instrument being compared.
g. Install. The act of emplacing, seating, or
fixing into position an item, part, module (component or
assembly) in a manner to allow the proper functioning of
the equipment or system.
h. Replace.
The act of substituting
a
serviceable like type part, subassembly, or module
(component or assembly) for an unserviceable
counterpart.
conditions.
This time includes preparation time,
troubleshooting time, and quality assurance/quality control
time in addition to the time required to perform the
specific tasks identified for the maintenance functions
authorized in the maintenance allocation chart.
Subcolumn of column 4 are as follows:
i.
Repair.
The application of maintenance
services (inspect, test, service, adjust, align, calibrate,
replace) or other maintenance actions (welding, grinding,
riveting,
straightening,
facing,
remachining,
or
C
O
-
-
Operator/Crew
Organizational
resurfacing) to restore serviceability to an item by
correcting specific, damage, fault, malfunction, or failure
in a part, subassembly, module (component or assembly),
end item, or system.
B-1
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F
H
D
-
-
-
Direct Support
General Support
Depot
b. Maintenance Category. The codes in this
column indicate the maintenance category allocated the
tool or test equipment
e. Column 5, Tools and Equipment. Column
5 specifies by code those common tool sets (not
individual tools) and special tools, test, and support
equipment required to perform the designated function.
c. Nomenclature. This column lists the noun
name and nomenclature of the tools and test equipment
required to perform the maintenance functions.
d. National/NATO Stock Number.
This
f.
Column 6, Remarks. Column 6 contains an
column lists the National/NATO stock number of the
specific tool or test equipment.
alphabetic code which leads to the remark in section IV,
Remarks, which is pertinent to the item opposite the
particular code.
e. Tool Number.
This column lists the
manufacturer's part number of the tool followed by the
Federal Supply Code for manufacturers (5-digit) in
parentheses.
B-4.
B-5.
Remarks (Sec IV)
a. Tool or Test Equipment Reference Code.
a. Reference Code. This code refers to the
The number in this column coincide with the numbers
used in the tools and equipment column of the MAC.
The numbers indicate the applicable tool or test
equipment for the maintenance functions.
b. Remarks.
This column provides the
required explanatory information necessary to clarify
B-2
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TM 11-6625-2779-14&P
SECTION II. MAINTENANCE ALLOCATION CHART
FOR
AUDIO LEVEL METER TA-885/U
(1)
(2)
(3)
(4)
(5)
(6)
MAINTENANCE CATEGORY
GROUP
NUMBER
MAINTENANCE
FUNCTION
TOOLS AND
EQUIPMENT REMARKS
COMPONENT ASSEMBLY
C
O
F
H
D
00
AUDIO LEVEL METER TA-885/U
(HP 3555B)
Inspect
Test
Service
Repair
Overhaul
0.5
7
0.5
0.8
1.2
1 thru 7
1 thru 7
1 thru 7
2.0 1 thru 7
B-3
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TM 11-7725-2779-14&P
SECTION III. TOOL AND TEST EQUIPMENT REQUIREMENTS
FOR
AUDIO LEVEL METER TA-885/U
TOOL OR
TEST
EQUIPMENT
REF CODE
MAINTENANCE
CATEGORY
NATIONAL/
NATO STOCK
NUMBER
TOOL
NUMBER
NOMENCLATURE
1
2
3
4
5
6
7
H,D
H,D
H,D
H,D
H,D
H,D
O
OSCILLATOR SG-1128/U, HP #654A
OSCILLATOR AN/URM-127
TRANSFORMER (LINE MATCHING) MX-8385/U
MULTIMETER AN/USM-451
AMPLIFIER HP-467A
VOLTMETER, ELECTRONIC ME-30 E/U
COMMON TOOLS NECESSARY TO THE PERFORMANCE OF
THIS MAINTENANCE FUNCTION ARE AVAILABLE TO
MAINTENANCE PERSONNEL FOR THE MAINTENANCE
CATEGORY LISTED.
6625-00-450-7590
6625-00-783-5965
6625-00-567-5837
6625-01-060-6804
6625-00-458-2480
6625-00-643-1670
B-4
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Model 3555B
APPENDIX C
Appendix C
MANUAL BACKDATING CHANGES
Model 3555B
TRANSMISSION AND NOISE MEASURING SET
This manual backdating sheet makes this manual applicable to earlier instruments.
Instrument-component values that differ from those in the manual, yet are not listed in
the backdating sheet, should be replaced using the part number given in the manual.
Instrument Serial Prefix
916-00500 and below
916-00509 and below
953-00544 and below
953-00825 and below
0992A01395 and below
0992A03536 and below
Make Manual Changes
1 thru 7
Instrument Serial Prefix
0992A03537 and below
Make Manual Changes
7
2 thru 7
3 thru 7
4 thru 7
5 thru 7
6, 7
Change No. 1
In instruments with S/N 916-00500 and below CR1 and C2 in the power supply were located as shown in the
following figure:
Change No. 2
A2C8 to 33pF, part no. 0160-2150
A2C9 to 320pF, part no. 0140-0226
A2C10 to 39pF, part no. 01400175
A2C11 to 51 pF, part no. 0160-2201
Change No. 3
Figure 7-4, change the pin connections as follows: 7 to 6, 13 to 12, 16 to 15, 15 to 13. Instruments with serial
numbers 953)00544 and below had a 03555-66506 Revision A board in them. This board is not interchangeable
with the Revision B board. The above pin connections are for the Revision A board.
Change No. 4
Delete S6 in figure 7-5 and in Table 6-1. Earlier instruments did not have this switch. See the following figure
for earlier instruments.
C-1
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Appendix C
Model 3555B
Change part no. of the case assembly to 03555-04505.
Change cover part no. to 03555-04504.
Change the part no. of the power cord to 81 20-0249.
Change the part no. of the power connector J1 to 1251-0148.
Change No. 5
Cover, battery
Bracket, meter
Panel, front
Assy. cover
Assy. case
00236-04104
00741-0 1209
03555-00203
03555-64504
03555-64506
0370-0440
Knob, pushbutton
Change No. 6
Change C2 to 0180-0110, 8 mF
Delete CR2 -4 1901-0025.
Change T1 part no. to 9100-1457.
Delete CR2 -4 from the Power Supply Rectifier.
Change No. 7
Delete CR6, 1901-0040.
Delete CR6 across M1.
*U.S. GOVERNMENT PRINTING OFFICE: 1980-603-128/66
C-2
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By Order of the Secretary of the Army:
E. C. MEYER
General, United States Army
Chief of Staff
Official:
J. C. PENNINGTON
Major General, United States Army
The Adjutant General
DISTRIBUTION:
Active Army:
HISA (Ft Monmouth) (21)
USAINSCOM (2)
COE (1)
TSG (1)
USAARENBD (1)
DARCOM (1)
TRADOC (2)
OS Maj Comd (4)
TECOM (2)
USAICS (3)
MAAG (1)
USARMIS (1)
USAERDAA (1)
USAERDAW (1)
Ft Carson (5)
Ft Gillem (10)
Ft Gordon (10)
(CERCOM Ofc)
USA Dep (1)
USACC (4)
MDW (1)
Armies (2)
Corps (2)
Sig Sec USA Dep (1)
Army Dep (1) except
LBAD (14)
Svc Colleges (1)
USASIGS (5)
SAAD (30)
TOAD (14)
USAADS (2)
SHAD (3)
USAFAS (2)
USAIS (2)
Units org under fol TOE:
29-207 (2)
USAFS (2)
29-610 (2)
ARNG: None
USAR: None
For explanation of abbreviations used, see AR 310-50.
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PIN: 043606-000
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