HP 4935A Service manual

Errata
Title & Document Type:
Manual Part Number:
Revision Date:
HP References in this Manual
This manual may contain references to HP or Hewlett-Packard. Please note that Hewlett-
Packard's former test and measurement, semiconductor products and chemical analysis
businesses are now part of Agilent Technologies. We have made no changes to this
manual copy. The HP XXXX referred to in this document is now the Agilent XXXX.
For example, model number HP8648A is now model number Agilent 8648A.
About this Manual
We’ve added this manual to the Agilent website in an effort to help you support your
product. This manual provides the best information we could find. It may be incomplete
or contain dated information, and the scan quality may not be ideal. If we find a better
copy in the future, we will add it to the Agilent website.
Support for Your Product
Agilent no longer sells or supports this product. You will find any other available
product information on the Agilent Test & Measurement website:
www.tm.agilent.com
Search for the model number of this product, and the resulting product page will guide
you to any available information. Our service centers may be able to perform calibration
if no repair parts are needed, but no other support from Agilent is available.
4935A Operating & Service
Manual
04935-90029
November 1966

Warnirlgs/(:autions
Model 4YXA
[ WARNING 1
SAFETY GROUNDING
If this instrument is to be energized via an autotransformer
for voltage reduction, make sure the common terminal is
connected to the earthed pole of the power source.
BEFORE SWITCHING ON THIS INSTRUMENT, the
protective earth terrninals of this instrument must be
connected to the protective conductor of the (mains)
power cord. The rnains plug shall only be inserted in a
socket outlet provided with a protective earth contact. The
protective actlon must not be negated by use of an
extension cord (power cable) without a protective con-
ductor (grounding).
Any interruption of the protective (grounding) conductor
(inside or outside the instrument) or disconnecting the
protective earth terminal can make this instrument
dangerous. Intentional interruption is prohibited.
HIGH VOLTAGE
Any adjustment, maintenance, and repair of the opened
instrument under voltage should be avoided as much as
possible and, when inevitable, should be carried out only by
a skilled person who is aware of the hazard involved.
Make sure that only fuses with the required rated current
and of the specified type (normal blow, time delay, etc.)
are used for replacement. The use of repaired fuses and the
short-circuiting of fuse holders must be avoided.
Capacitors inside the instrument may still be charged even
if the instrument has been disconnected from its source of
SUPPlY.
Whenever It is likely that the protection offered by fuses
has been impaired, the instrument must be made
inoperative and be secured against any unintended
operation.
Adjustments and service described herein are performed
with power supplied to the instrument while protective
covers are removed. Energy available at many points, if
contacted, result in personal injury.
LINE VOLTAGE
BEFORE SWITCHING ON THIS INSTRUMENT, make
sure instrument requirements match the voltage of the
power source.
BEFORE SWITCHING ON THIS INSTRUMENT, ensure
that the line power (mains) plug is connected to a
three-conductor line power outlet that has a protective
(earth) ground. (Grounding one conductor of a two-
conductor outlet is not sufficient.)
GROUNDING
BEFORE SWITCHING ON THIS INSTRUMENT, ensure
that all devices connected to this instrument are connected
to the protective (earth) ground.
ii

Model &%A IEC Symbols
IEC SYMBOLS
The follownq IS rl 1151 of key I EC symbols used by Hewlett-Packard. All symbols
are normally applwd adlacent to the device requur~ng the symbol. They shall not
be placed on removable parts likely to be detached or lost.
A
!
1
-
-
---
A
V
VA
w
Wh
VAh
lnstrucf~on Manual symbol: If necessary. to preserve the
apparatus from damage !t IS necessary for the user to refer to
the mstruct~on manual, then shall the apparatus be marked
wth thlssymbol (IEC 348;16a).
Termnal dewces fad from the ~ntertor by live voltages that
may be dangerous when connecting to or dlsconnectlng from
those dewces shall be marked wth the flash shown when the
volrdge exceeds 1 KV: The flash shall be red (IEC 348;lEc).
Earth Termunals. If the use of this symbol for the protectwe
earth termmal 1s not permttted by National Standards, it may
be modlfled. for example, by bang placed irwde a circle (IEC
348.18a).
AC current (IEC 117-l. symbol No. 3).
DC current fIEC 117-l. symbol No. 2).
AC or DC current (I EC 1 17-l. symbol No. 8).
Frame or chaws connection. The hatchmg may be com-
pletely or partly omitted if there II no ambiguity. If the
hatching is omated, the line representing the frame or chassis
shall be thrcker (I EC 117.1, symbol No. 87).
Ampere (IEC 1174, symbol No. 356).
Volt lltC 1174. symbol No. 357).
Voltampere (I EC 1174, symbol No. 358).
Watt (I EC 1174, symbol No. 3601.
Watthour (I EC 1174, symbol No. 361).
Voltamperehour (IEC 1174, symbol No. 362).
HZ Hertz (IEC 1174. symbol No. 365).
z
Contactor, normally closed. In order to avold confusion with
the symbol for a capacitor. the deance between the
horizontal (as drawn here) lines should be at least equal to
the length of those lines (IEC 117-3, symbol No. 215.21.
In addltlon the following describes the use of Warmngs. Cautions and Notes used
in HP Automatic Test System Manuals.
Warnings, cautions and notes. (All) Warmngs and caut!ons shall precede the text
to which each apples but notes may precede or follow applicable text depending
on the material to be highllghted. Warnings, cautions, and notes shall not contan
procedural steps nor shall they be numbered. When a warmng, caution, or note
consists of two or more paragraphs, the heading WARNING, CAUTION, NOTE,
shall not be repeated above each paragraph. If it is ever necessary to precede a
paragraph by both a warmng and a note, or a caution and a note, etc. they shall
appear m the sequence as noted, namely. warnings. cautions, notes. Such inserts
I” the text shall be short and concise and be used to emphasize important and
critical mstructtons.
An operating procedure, practtce. etc. which. If not
correctly followed, could result III personal injury or
loss of life.
An operating procedure, practw, etc. which, if not
strictly observed, could result tn damage to, or
destruction of, eqwpment.
NOTE: An operating procedure, condmon, etc. whwzh
it is essential to hIghlIght.
-health hazards precaution data. (All) When hazardous chemicals or adverse health
factors, in the environment or use of the equipment cannot be eliminated,
,tppropriate precautionary requirements shall be mcluded.
iii/(iv blank)

Model 4935A Table of Contents
TABLE OF C:ONTENTS
Section Title Page Section Title Page
I. GENERAL INFORMATION
l-l. Introduction.. ................................................... l-l
l-3. General Description.. ..................................... l-l
l-5. Instrument Identification.. .............................
l-1
l-7. Specifications.. ................................................. l-l
l-9. Safety Considerations.. ..................................
.1-4
1-12. Related Manuals............................................. l-4
1-14. User Repair.. ................................................... l-4
1-16. Options
and Accessories.. .............................. l-4
1-19. Warranty.. ......................................................
..l- 4
1-21. Recommended Test Equipment.. ................. l-4
l-23. Battery Operation (0pt.s 001 & 003) ..........l-6
l-26. Charging the Batteries.. ........................... l-6
l-29. Operating Temperature.. ......................... l-6
3-48. Signal Frequency Interference .................... .3-24
3-52. Impulse Noise.. .............................................. .3-24
3-55. Noise-to-Ground Measurement.. ................ .3-25
3-59. Peak-to-Average Ratio Measurement.........3-2 5
IV. PERFORMANCE TESTS
II. INSTALLATION
2-l. Introduction.. ..................................................
.2-l
2-3. Initial Inspection.. ..........................................
.2-l
2-6. Preparation for Use....................................... .2-l
2-7. Power Requirements.. ...................................
.2-l
2-9. Line Voltage Selection................................... 2-l
2-11. Power Cable.. ................................................. .2-2
2-13. Operating Environment.. .............................. .2-2
2-16. Storage and Shipment.. ................................. .2-2
2-17. Environment.. ........................................... .2-2
2-19. Instrument Packaging ................................... .2-2
4-l. Introduction ...................................................
.4-l
4-3. Equipment Required.. ..................................
.4-l
4-5. Test Record ...................................................
.4-l
4-7. Self Check ...................................................... .4-l
4-9. Performance Verification.. ...........................
.4-l
4-12. Performance Tests........................................ .4-2
4-13. Transmitter Flatness at + 10dBm..
........ .4-2
4-14. Transmitter Flatness at -40dBm.. ..........
.4-4
4-15. Receiver Accuracy at t 1ldBm
&-4OdBm..
..............................................
.4-8
4-16. Autorange Test........................................ .4-10
4-17. Filter Tests.. ............................................. .4-11
4-18. Impulse Noise DACTest.......................
.4-14
4-19. Count Limit Test.. ................................... .4-16
4-20. Termination Impedance
Test.. .............. .4-17
4-21. Hold Tone Dropout Detector Test........4-19
4-22. Hold Circuit Test.................................... .4-20
4-23. Distortion Test ........................................ .4-21
4-24. P/AR Test..
.............................................. .4-25
4-25. Noise-to-Ground(Std. dc Opt. 001). ...... .4-26
V. ADJUSTMENTS/CALIBRATIONS
III. OPERATION
3-l. Introduction.................................................... .3-l
3-3. Self Check.......................................................
.3-l
3-5. Error Messages.. ............................................
.3-l
3-7. Operating Instructions .................................. .3-6
3-9. Measurements ................................................ .3-7
3-10. Measurement Principles ............................... .3-17
3-12. Input-Output Switching ................................ .3-17
3-19. Level and Frequency Measurements..
........ .3-18
3-21.
1000 HzLoss.................................................. .3-18
3-24. Frequency Shift .............................................. .3-18
3-26. Attenuation Distortion.. ................................ .3-18
3-30. SF Skip ............................................................ .3-19
3-32. Message Circuit Noise Measurements..
.... ..3-19
3.40. Noise Measurements.....................................
.3-22
3-42. Noise-with-Tone (Notched Noise) ...............3-22
3-45. Signal-to Noise Measurement.. .................... .3-22
5-l. Introduction ...................................................
.5-l
5-3. Safety Considerations.. ................................. .5-l
5-5. Equipment Required.. ..................................
.5-l
5-6. Instrument Access.. ................................. .5-l
5-9. Adjustment Locations...................................
.5-l
5-11. Adjustments.. .................................................
.5-2
5-13. t 5V, + 14V, and -14V Power
Supply Adjustments ......................................
.5-3
5-14. Output Level & Transmit
Monitor Loop Adjustments.. .................
.5-4
5-15. Receiver Adjustments................................... .5-5
5-17. Notch Filter Adjustments.............................
.5-7
5-18. Al3 P/AR Filter and Latch
Adjustments(0pt.s
001 & 003). ................... .5-8
5-19. Hold Circuit Adjustments.. ....................
.5-9
V

Table of Contents Model 4935A
TABLE OF CONTENTS (cord)
Section Title Page Section Title Page
VI. REPLACEABLE PARTS
6-l. Introduction.. ..................................................
.6-l
6-3. Replaceable Parts List.. ............................... ..6- 1
6-5. Ordering Information ................................... .6-l
VII. MANUAL CHANGES
7-1. Introduction .................................................... .7-l
7-3. Manual Changes.. .......................................... .7-l
7-6. Manual Change Instructions.......................... 7-l
VIII. SERVICE
8-l. General Information .................................... ..8- 1
8-8. How Measurements are Made ....................
.8-3
8-10. Level and Frequency.. ............................. .8-4
8-13. Noise.. ......................................................... 8-4
8-16. Noise-with-Tone ...................................... .8-4
8-19. Signal-to-Noise.. ....................................... .8-5
8-22. Impulse Noise .......................................... .8-5
8-26. Noise-to-Ground (Std & Opt. 001). ...... .8-6
8-29. Peak-to-Average Ratio: P/AR
(0pt.s 002 & 003) .................................... .a-6
8-32. Frequency Measurement.. ............................ .8-6
8-34. Level Measurement.. ..................................... .8-7
8-38. How to Compute Frequency and Level
Measurement ................................................. .8-8
8-39. Level Calculation Example.. ................... .8-8
8-42. Control Theory of Operation....................... .8-11
8-44. Microprocessor to Instrument.. ................... .8-11
8-45.
System Latches......................................... .8-H
8-48. Instrument to Microprocessor.. ................... .8-12
8-51. Operator to Microprocessor ........................ .8-12
8-52. Keyboard Interrupt.. ................................ .8-12
8-54. Receiver Impedance
Switches.. .............. .8-12
8-57. Microprocessor to Operator.. ...................... .8-13
8-58. Displays..................................................... .8-13
8-60. Instrument to Operator ................................ .8-13
8-62. Monitor Amp ........................................... .8-13
8-64. Beep Generator ....................................... .8-13
8-66. Operator to Instrument ................................ .8-13
8-68. Miscellaneous Circuitry................................ .8-13
8-73. Receiver Theory of Operation..................... .8-15
8-76. I/O Switching/Hold Circuits/
Termination .............................................. .a-16
8-80. Input Select/Notch Filter/
25 dB Amp.. ............................................. .8-17
8-85. Noise Filter Circuitry.. ............................ .8-17
8-97. Level Detectors ....................................... .8-19
8-100. Impulse Noise Detectors.. ...................... .8-19
8-102. Transmitter .................................................... .8-19
8-104. Test Signal Generation Method.. .......... .8-20
811.3. Circuit Description.. ................................ .8-21
8-126. Power Supply Theory.................................... .8-23
8-128. AC Line Supplies .................................... .8-23
8-131. Regulators.. .............................................. .8-24
8-139. Charger Board Theory of Operation.. ........ .8-25
8-141. Battery Charging.. ................................... .8-26
8-144. Power Source Selection.. ........................ .8-26
8-146. Relay Drive Circuitry.. ............................ .8-26
8-148. Inhibit Circuit ........................................... 8-26
8-153. Maintenance .................................................. .8-28
8-1.55. Periodic Maintenance.. ........................... .8-28
8- 157. Failure Maintenance.. ............................. .8-28
8-159. Component Replacement ...................... .8-28
8-164. Soldering .................................................. .8-28
8-166 . Cleaning.. .................................................. .8-28
8-168. Disassembly .................................................... 8-29
8-169. Remove Case.. .........................................
.8-29
8-171. Receiver Board/Shield Plate/
Battery Charger Board Disassembly.. ........ .8-29
8-173. Switchboard/Front Panel Removal.. .......... .8-30
8-175. Transmitter Board Removal.. ...................... .8-30
8-177. Reassembly.. .................................................. .8-31
8-179. Power Supply Troubleshooting................... .8-33
8-181. Minimum Core Troubleshooting................ .8-34
8-183. Procedure .................................................. 8-35
8-186. Display Troubleshooting.. ...................... .8-36
8-189. Control Troubleshooting.............................. .8-36
8-190. Troubleshoot Keyscan/
Interrupt Circuitry.. ................................. .8-36
8-192. Control and Counting Section
Troubleshooting.. .......................................... .8-36
8-194. Transmitter Troubleshooting ...................... .8-37
8-196. Transmit Clock Generator.. ...................
.8-37
8-200.
Transmitter Signature Analysis
Procedure.. ............................................... .8-37
8-202. Digital-to-Analog Conversion ............... .8-39
8-204. Filter and Signal Select Circuitry.. ........ .8-40
8-207. Output Amplifier.. ................................... .8-42
8-210.
Transmit Monitor.. .................................. .8-43
8-212. Receiver Troubleshooting............................ .8-43
vi

Model 4935A Table of Contents
TABLE OF CONTENTS
Section Title Page Section Title Page
8-217.
8-219.
8-222.
8-225.
8-227.
8-229.
8-232.
8-233.
8-235.
8-237.
8-239.
8-242.
Setup.......................................................... .8-44
Overall Transmit Monitor Test ............. .8-44
Transmit Monitor Signal ........................ .8-45
Noise Filter.. ............................................. .8-45
Simplified Autorange Check.. ................ .8-46
Detector Select......................................... .8-47
Inputs from Front Panel/
Notch Filter/ 25dB Amp/Tone
Dropout Signal Path.. .............................. .8-47
Setup.......................................................... .8-48
Input Transformer.. ................................. .8-48
Noise-to-Ground Input Path
(Noise-to-Ground Units only) ............... .8-48
Tone Dropout Signal Path...................... .8-49
Notch Filter .............................................. .8-49
8-259. Relay Drive Circuitry,
Low Voltage Inhibit Circuitry.. ............. .8-53
8-261. Inhibit Circuitry AC and
Low Voltage.. ........................................... .8-54
8-263. Delay and Relay Drive Circuitry.. ......... .8-54
8-265. AC and Low Voltage Inhibit
Troubleshooting ...................................... .8-55
8-267. Service Aids ................................................... .8-57
8-268. Service Selection of Input/
Notch Filter/25dB Amp.. ............................. .8-57
8-270. Procedure.. ............................................... .8-57
8-272. Service Selection of Noise Filters
by Hand.. ........................................................ .8-58
8-274. Procedure ................................................. .8-58
8-276. Service Selection of Autorange
Gain for Service............................................. .8-58
8-278. Procedure ................................................. .8-58
8-279. Hand Selection of AX57 and A3C160
(A3C57 and A3C160 for P/AR Units)
for Desired Frequency Response.. .............. .8-59
8-282. Hand Selection of C57 and Cl60.. ........ .8-60
8-283. FiIters: Response of Each Stage.................. .8-60
8-246. Noise Filters ................................................... .8-49
8-248. Autorange ................................................. .8-49
8-250. Detector Troubleshooting.. .................... .8-50
8-252. Impulse Noise Circuitry.. .............................. .8-50
82.54. Charger Board Troubleshooting ................. .8-52
8-255. Procedure ................................................. .8-52
8-257. Charge Circuitry/Charge
Inhibit Circuitry ....................................... .8-52
vii

Table of Contents
Model 4935A
LIST OF ILLUSTRATIONS
Section Title Page Section Title Page
l-l. Model 4935A Transmission Impairment
Measuring Set
................................................ .1-O
l-2. Charge Acceptance at Various
Tempcraturcs.. ................................................ l-6
5-1. Output Level and Transmit Monitor
Loop Adjustments.. .......................................
.5-4
5-2. Receiver Adjustments...................................
.5-5
5-3. Hold Circuit Adjustments............................
.5-9
2-l. Lint Voltage Selection.. ................................ .2-l
3-l. Front and Rear Panel Controls/
Connectors/indicators..
................................ .3-2
3-2. Measurements ................................................ .3-6
3-3. Input-Output Switching ................................. 3-17
3-4. Level and Frequency Mcasurcments.......... .3-18
3-5. Message Circuit Noise Measurements ...... ..3-19
3-6. C-Mcssagc Weighting Characteristic.......... .3-20
3-7. 3 kHz Flat Weighting Characteristic.. ......... .3-20
3-8. Program Weighted liltcr.. ............................. .3-21
3-9. 15 kHz Flat Filter .......................................... .3-21
3-10. SOkBit Filter.
................................................... .3-22
3-11. C-Message Weighting with Notch
Characteristic.. ............................................... .3-23
3-12. Signal-to-Noise Measurement ..................... .3-23
3-13. Impulse Noise Waveform
Rcprcscntation.. ............................................. .3-24
3-14. Noise-to-Ground Related to Message
Circuit Noise..................................................
.3-2.5
3-15. P/AR Transmit Signal Frcqucncy
Spectrum.. ....................................................... .3-26
3-16. P/AR Transmit Signal Envelope.. ............... .3-26
6-l. Exploded View Case and Covers.................6-4
6-2. Exploded View Assemblies and Cables..
.. ..6- 5
6-3. Exploded View Battery Option...................
.6-7
4-l. Transmitter Flatness Test
at +10 dBm
.................................................... .4-2
4-2. Transmitter Flatness Test
at -40 dBm ...................................................... .4-4
4-3. Reccivcr Test at + 11 dBm
and -40 dBm ................................................... .4-8
4-4. Autorangc Test .............................................. .4-10
4-5. Filter Tests.. .................................................... .4-11
4-6. Impulse Noise DAC
Test ............................. .4-14
4-7. Count Limit
Test ........................................... .4-16
4-8. Termination Impedance Test....................... .4-17
4-9. Hold Tone Dropout Detector Test..
........... .4-19
4-10. Hold (Xrcuit ‘Test.. ......................................... .4-20
4-11. Distortion Test ................................................ 4-21
4-12. -40 dBm Distortion Test.. ............................. .4-22
4-13. Filter Circuits ................................................. .4-23
4-14. P/AR Test.. .................................................... .4-25
4-15. Noise-to-Ground Test.. ................................. .4-26
7-l. A2 Switch Board Component Locator..
.... ..7-10
7-2. A5 Charger Board Component Locator.. . ..7-14
7-3. Partial A5 Charger Board Schematic.. ....... .7-14
7-4. Al4 Transmitter Board Component
Locator ........................................................... .7-15
7-5. Partial A4 and Al4 Schematic ...................... 7-16
7-6. Al4 P/AR Transmitter Board
Component Locator.. .................................... .7-16
7-7. A4 Transmitter Board Component
Locator ........................................................... .7-17
7-8. Partial Power Supply Schematic.................. .7-18
7-9. Al3 P/AR Receiver Board Component
Locator ........................................................... .7-19
7-10. A3 Receiver Board Component
Locator ........................................................... .7-20
7-11. A3 Receiver Board Schematic
(Sheet
1 of 2) ................................................. .7-21
7-12. A3 Receiver Board Schematic
(Sheet 2of 2) ................................................. .7-23
7-13. Al3 P/AR Receiver Board Component
Locator ........................................................... .7-25
7-14. A3 Receiver Board Component
Locator ........................................................... .7-26
7-15. A3 Receiver Board Schematic
Diagram (Partial). ......................................... .7-27
7-16. A4 Transmitter Board Component
Locator ........................................................... .7-28
7-17. Al4 Transmitter Board Component
Locator ...........................................................
.7-28
7-18. A4 Transmitter Board Schematic
Diagram ......................................................... .7-29
7-19. Al4 Transmitter Board Schematic
Diagram (Partial). ......................................... .7-30
7-20. Al4 Transmitter Board Schematic
Diagram (Partial). ......................................... .7-30
7-21. A2 Switchboard Component Locator..
....... .7-32
7-22. A2 Switchboard Schematic Diagram.. ........ .7-33
7-23. A3 Receiver Board Component
. . .
VW

Model 4935A Table of Contents
LIST OF ILLUSTRATIONS
Section Title Page Section Title Page
Locator.. .......................................................... .7-34
7-24. Al3 Receiver Board Component
Locator.. .......................................................... .7-35
7-25. Receiver Board Schematic
Diagram (Sheet 1 of 2) ................................. .7-36
7-26. Receiver Board Schematic
Diagram (Sheet 2of 2) ................................. .7-37
7-27. A4 Transmitter Board Component
Locator.. .......................................................... .7-38
7-28. Al4 Transmitter Board Component
Locator ............................................................ .7-39
7-29. A4 Transmitter Board Schematic
Diagram (Sheet 1 of 2) ................................. .7-40
7-30. A4 Transmitter Board Schematic
Diagram (Sheet 2 of 2) .................................
.7-41
7-31. A5 Charger Board Component Locator......7-4 2
7-32. A5 Charger Board Schematic Diagram.......7-4 3
8-l. 4935A Main Block Diagram.. ....................... .8-l
8-2. Voltage-to-Frequency Conversion
Characteristics ................................................. 8-7
8-3. Voltage-to-Frequency Conversion
output ............................................................. .8-8
8-4. Frequency and Level Measurement
Timing.. ........................................................... .8-9
8-5. Control Circuitry Block Diagram................ .8-11
8-6. Receiver Block Diagram.. ............................. .8-14
8-7. Switchboard Block Diagram ........................ .8-15
8-8. Input-Output Switching ................................ .8-16
8-9. Filter Block Diagram .................................... .8-17
8-10. Autorange Block Diagram ........................... .8-18
8-11. Stair-Step Sinewave.. ..................................... .8-20
8-12. Transmitter Block Diagram ......................... .8-21
8-13. Power Supply Block Diagram.. .................... .8-23
8-14. Charger Board Block Diagram.. .................. .8-25
8-17. Instrument Troubleshooting ........................ .8-32
8-18. Stair-Step Sinewave.. ..................................... .8-39
8-19. P/AR Signal Frequency Spectrum ..............8-41
8-20. P/AR Transmit Signal Envelope................ .8-42
8-21. 20 HzWaveform ........................................... .8-43
8-22. Transmit Monitor Test Output ................... .8-44
8-23. 4935A Signal Flow Block Diagram............. .8-67
8-24. Al Front Panel Schematic Diagram............8-69
8-25. A2 Switchboard Component Locator.. ....... .8-70
8-26. A2 Switchboard Schematic Diagram.. ........ .8-71
8-27. A3 Receiver Board Component
Locator ........................................................... .8-72
8-28. Al3 Receiver Board Component
Locator ........................................................... .8-72
8-29. A3 Receiver Board Schematic
Diagram (Sheet 1 of 4)................................. .8-73
8-30. A3 Receiver Board Schematic
Diagram (Sheet 2of 4)................................. .8-75
8-31. A3 Receiver Board Schematic
Diagram (Sheet 3 of 4)................................. .8-77
8-32. A3 Receiver Board Schematic
Diagram (Sheet 4of4). ................................ .8-79
8-33. A4 Transmitter Board Component
Locator ........................................................... .8-80
8-34. Al4 Transmitter Board Component
Locator ........................................................... .8-80
8-35. A4 Transmitter Board Schematic
Diagram (Sheet 1 of 5)................................. .8-81
8-36. A4 Transmitter Board Schematic
Diagram (Sheet 2 of 5). ................................ .8-83
8-37. A4 Transmitter Board Schematic
Diagram (Sheet 3 of 5)................................. .8-85
8-38. A4 Transmitter Board Schematic
Diagram (Sheet 4of 5). ................................ .8-87
8-39. A4 Transmitter Board Schematic
Diagram (Sheet 5 of 5)................................. .8-89
8-40. A5 Charger Board Component Locator.. .. ,890
8-41. A5 Charger Board Schematic Diagram.. .. ..8-9 1
ix

Table of Contents
Model 4935A
LIST OF TABLES
Table Title Page Table Title Page
l-l.
l-2.
l-3.
Specificalions..
................................................. l-2
Recommended
Test Equipment.. ................. l-5
List of Parts Used for Performance
Tests ................................................................. l-5
7-l. Manual Changes............................................ .7-l
2-l. HP Plug
Styles.. ............................................... 2-3
4-1.
4-2.
4-3.
4-4.
4-5.
4-6.
4-7.
4-8.
4-9.
4-10.
4-11.
4-12.
4-13.
4-14.
4-15.
4-16.
Transmitter Flatness at + 10 dBm ............... .4-3
Transmitter Flatness at -40 dBm.. ............... .4-5
Abbreviated Transmitter Flatness................4-7
Receiver Accuracy Test Table ..................... .4-9
Abbreviated Receiver Accuracy
Test Table.. ..................................................... .4-9
Autorange Test
.............................................. .4-10
C-Message Filter Test................................... .4-11
3 kHz Filter Test............................................ .4-12
15 khz flat Filter Test.. .................................. .4-12
Program Filter Test....................................... .4-12
50 kBit Filter Test.......................................... .4-13
Notch Filter
Test.. .......................................... .4-13
Impulse Noise DACTest ............................. .4-15
Filter Circuit Parts List.. ............................... .4-23
Abbreviated Distortion Test ........................ .4-24
P/AR Filter
Responses ................................ .4-25
6-l.
6-2.
6-3.
Reference Designation and
Abbreviations ................................................. .6-2
Manufacturer
Code List ............................... .6-8
Replaceable Parts.. ........................................
.6-9
8-l. Measurements Summary.. ............................
.8-3
8-2. Noise Amplification....................................... 8-5
8-3. Reference Signatures.. .................................. .8-38
8-4. Wideband Filter Response ........................... S-40
8-5. 5 kHz Low Pass Filter Response .................8-40
8-6. Output Select MUX.. .................................... .8-41
8-7. Transmit Monitor Test................................. .8-43
8-8. A3UlB Voltages ........................................... .8-51
8-9. TP3 Voltages ................................................. .8-51
S-10. Hand Selection of Noise Filters .................. .8-58
8-11. Autorange States........................................... .8-59
8-12. Hand Selection of C57 and Cl60.. .............. .8-60
8-13. 4935A C-Message Filter.. ............................. .8-61
8-14. 4935A 3 kHz Filter.. ...................................... .8-61
8-15. 4935A 15
kHz Filter...................................... .8-61
8-16. 4935A Program Filter.. ................................. .8-61
8-17. 4935A 50 kBit Filter.. .................................... .8-62
8-18. 4935A Notch Filter.. ...................................... .8-62
8-19. 4935A P/AR Filter ....................................... .8-62
8-20. 4935A 150 kHz Low Pass Filter .................. .8-62
8-21. 4935A 110 kHz Low Pass Filter .................. .8-63
8-22. Bell 41009
C-Message Filter.. ...................... .8-63
8-23. Bell 41009 3 kHz Filter................................. .8-64
8-24. Bell 41009 15 kHz Filter.. ............................. .8-64
8-25. Bell 41009 Program Filter.. .......................... .8-64
8-26. Bell 41009 50
kBit Filter.. ............................. .8-65
8-27. Bell 41009 P/AR Filter ................................
.8-65
8-28. Bell 41009 Notch Filter.. ...............................
.8-65
x /(xi blank)

(hctral Inii,rmi,ti~,,,
Model 4935A
Figure f-1. Model 4935A f
ransnhdon
Impairment Measuring set

Model 4935A . t General Information
SECTION I
GENERAL INFORMATION
l-l. INTRODUCTION
1-2. This Operating and Service manual contains information to install, operate, maintain, and service
the HI’ Model 49:{5A Transmission Impairment Measuring Set (TIMS). Figure 1-l shows the HP Model
49XA with cover and power cord. The manual is divided into eight major sections which provide the
following information:
SECTION I. GENERAL INFORMATION. Provides identification, specifications, related
manuals, and user-repair information.
SECTION II. INSTALLATION. Contains unpacking and inspection information, power
requirements, packaging, and storage instructions.
SECTION III. OPERATION. Includes an explanation of controls, connectors, indicators, and an
automatic self check procedure. Describes measurement principles and front panel instructions for
making each measurement.
SFCTION IV. PERFORMANCE TESTS. C’ xtves test procedures required to verify that the
instrument’s performance is in accordance with the specifications.
SECTION V. ADJUSTMENTS. Provides adjustment and calibration procedures.
SECTION VI. REPLACEARLE PARTS. Lists and identifies the instrument assemblies and
replaceable parts.
SEXTION VII. MANUAL CHANGES. Cor
ams information to backdate the manual fort
instruments with earlier serial numbers.
SECTION VIII. SERVICE. Includes theory of operation, troubleshooting procedures, flowcharts,
component locators, and schematic diagrams.
1-3.
GENERAL DESCRIPTION
l-4. HI’ Model
49XA is a Transmission Impairment Measuring Set (TIMS) which measures wideband
data and voice impairments. The frequency range over which measurements are made is 20 Hz to 110 kHz,
in steps of I, 10, 100, 1000, or 10,000 Hz. There are four permanently stored, fixed frequencies -404, 1004,
2804. and 271:s Hz. Any other four frequencies may be temporarily assigned and stored by the user.
1-5. INSTRUMENT IDENTIFICATION
l-6. A IO character serial number (OOOOAOOOOO) is inscribed on the rear panel. The first four digits and
the letter are the serial prefix. The serial prefix will change only if changes are made to the instrument; a
Manual Change Sheet will be included with the manuals of any instruments affected. Thelast five numbers
form the serial suffix which is unique to each instrument.
1-7. SPECIFICATIONS
l-8. Instrument specifications are listed in Table I -1.
l-l

Table l-l. Specifications
Model 49:EA
TRANSMITTER RECEIVER
Frequency Frequency
Frequency Range . . . . . . . . . .20 Hz to 110 kHz
Resolution Accuracy
Frequency Range.. . . . . . . . . . . . .20 Hz to 110 kHz
Resolution Accuracy
20-99,999 Hz
1 Hz f .005% of output frequency 20-9.999 Hz 1 Hz
kO.5 Hz
100-l 10 kHz 10 Hz
t .012% of output frequency 10-110 kHz
10 Hz +5 Hz
Store and Recall Functions
SK Skip . . . At power up skips a band from 2450-2750 HZ
Frequencies . . . . . At power up Fl is 404 HZ
F2 is 1004 Hz
F3 is 2804 Hz
F4 is 2713 Hz
Level
Range . . . . . . . . . . . . . . . .-40 to +13 dl3m
Resolution . . . . . . . . . . . . . . . . . . . . . 0.1 dB
Flatness . . . . . . . . . . . . . . . . . _. . . . . . . _(in dB)
FREQUENCY, Hz
20 200
15k
60k 85k
1 IOk
z+13
+im
g;+1;
3 -40
Distortion: (in dB from fundamental)
(Includes harmonics, spurious and background noise within
a filter with a 3 dB bandwidth of 4 kHz or 4 f0, whichever
is greater.)
FREQUENCY (Hz)
_ 30 Hz 100 Hz 4k IlOk
At 1004 Hz, 0 dBm, THD using a 4 kHz filter is more than
65 dB down from the fundamental.
Message Circuit Noise
Transmitter is quiet terminated
Level
Range . .._........................ -6Oto+13dBm
Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.1 dB
Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (in dl3)
FREQUENCY (Hz)
20 50 200
15k
60k 85k
1 IOk
z-+13
5:
Q---40
K.s
3-60
Receiver accuracy not specified below 500 Hz when using
13562 termination.
At 1004 kHz accuracy is fO.l dB from -20 to +I3 dBm.
Cross talk: >78 dB isolation @ 4 kHz, decreasing 6 dB per
octave above 4 kHz.
Message Circuit Noise
Range (@ 6OOa and 9OOn) . . . . . . . . . . .O to 100 dBrn
@ 13516 lower limit is 7 dB higher
Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 dB
Accuracy . . . . . . . . . . . . . . .
.+ 1 dB from IO to 100 dBrn
+2 dB from 0 to IO dBrn
Filters . . . . . . . . . . . .C-Message, 3
kHz Flat, 15 kHz Flat,
Program, 50 kBit
Specifications describe the instrument’s warranted performance. Supplemental characteristics shown in shaded areas or in
italics are intended to provide information useful in applying the instrument by giving typical, but non-warranted
performance parameters.

Model 4935A
General Information
TRANSMITTER
Noise with Tone
Frequency . . . . . . . . . . . . . . 1004 Hz fixed tone
(For other specifications, see Level and Frequency)
Signal-to-Noise Ratio
Frequency . . . . . . . . . . . . . . . . 1004 Hz fixed tone
(For other specifications, see Level and Frequency)
3-Level Impulse Noise
Frequency . . . . .1004 Hz fixed tone or quiet terminated
depending on filter selection
(For other specifications, see Level and Frequency)
Table l-l. SpecificatilJns (Continued)
1
RECEIVER
Noise with Tone
Notch Filter. .....
>50 dB rejection from 995 to 1025 HZ
Range (@ 600R and 900R)
.............. IO-100
dBrn
Accuracy ................. ?I dB from 20 to 100 dBrn
*2 dB from 10 to 20 dBrn
(For other specifications, refer to Message Circuit Noise)
Noise-to-Ground
Transmitter is quiet terminated
P/AR (Optional)
Frequency . . Signal spectrum is a complex pulse train of
16 frequencies between 140 Hz and 3890 Hz.
Level Range . . . . . . . . . . . . . . . . . . . . .-40 to 0 dBm
Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 dB
Signal-to-Noise Ratio
Signal Level Range .................. .-40 to +I 3 dBm
Ratio Range ........................... IO to 45
dB
Resolution ................................. .I dB
3-Level Impulse Noise
Level Range ....................... .-40 to
+I3 dBm
Notch Filter. ................... .See Noise with Tone
Threshold Ranges (@ 6OOfi)
Low ............................. .30 to 109 dBrn
Mid
High : : : : ....
.4 dB above Low to a maximum of 109 dBrn
.8 dB above Low to a maximum of 109 dBrn
Loss of Holding Tone Indication ............ Minus sign
Threshold Accuracy (above 40 dBrnl
............
+1 dB
Count Timer ............... 5, 15,60 min. or non-stop
Count Range ............... O-9999 for each threshold
Count Rate ............................. 8per sec.
Noise-to-Ground
Range (@ 600R and 9OOfi)
............
.50 to 130 dBrn
Resolution .................................. 1
dB
Accuracy ................................
+I .5 dl3
P/AR (Optional)
P/AR Range. .................. .O to 120 P/AR units
Resolution ........................... 1 P/AR unit
Accuracy (from 30 to 110 P/AR units) ... +2 P/AR units
Level Range ....................... .-40 to
+3 dBm
Resolution ................................ .I dB
Temperature Range:
Operating . . . . . . . . . . . . . . 0°C to 50°C (32’F to 122°F)
with batteries O°C to 40°C (32OF to 104OF)
Storage . . . . . . . . . . -20°C to 75’C (-4OF to 167OF)
with batteries -2O’C to 45’C (-4’F to 113°F)
Warm up time @ 20°C for stated accuracy . . . . . . . . .5 min.
Dimensions .I 1.2 x 25.9 x 28.6 cm (4.4 x 10.2 x 11.25 in.)
Weight . . . . . .5.0 kg (11 Ibs.), 6.5 kg (14 Ibs.) with battery
OPTIONS
001 . . . . . . . . . . . . . . . . . Adds rechargeable battery pack
002 Adds P/AR measurement in place of Norse-to-Ground
003 . . . . . . . . . . . . . Adds both battery pack and P/AR
Deletes Noise-to-Ground
ACCESSORIES:
15513A . . . . . . . . . Test cord w/31 0 male at both ends
18132A . . . . . . . . . . . . . . . . . . . 19” rack mount adapter
18134A . . . . . . . . . . . . . . . . . . . . . Soft pack carrying case
18161 A . . . . . . . . . . . . . . . . . . . . . , . . . . . . . Ladder bracket
I-3

(;cnt~r:tl Inf’orm;rtIotl
1-9. SAFETY CONSIDERATIONS
1-12. RELATED MANUALS
1 1:; ( lI)t.ritting int’t~rtnation is summariztd on it t,arcl in the instrumt~nt t‘ovtsr.
l-14. USER REPAIR
I I .-I. 1 ntctrnal rthpairs tcl thta instrument should t)rl dents by ;tuthoriztd rtbpair shops only. I~orassistant~t~,
c,ont;it.t thus tlta;lrtsst t It~u,l~~tt-~‘at,kartl Sales antI Servit,ta Of’fit~, listed at the r(‘ar of’ this manual.
1-16. OPTIONS AND ACCESSORIES
()I)( eon 002: Adds 1’ Al< (I’ta;ik! Avrragts Ratio) mr;lsurt~mrnt in Plato of’ Nois+to-(;round
I -%(I. Itlstrumr~nt warranty is as listctl on thth insidtx of’ the f’ront c’ovt’r. Hattc~ry warranty is 90 days
1-21. RECOMMENDED TEST EQUIPMENT
l-22.
tit~t~~~rnmc~ntlt~tl ttsst tquipmt~nt is listed in ‘I’whlt~ l-2. Equipment with quivnlcnt characteristics
m;,y tit) llS~‘(l
1 -4

Model 4935A
Table 1-2. Recommended Test Equipment
INSTRUMENT
I
CRITICAL SPECIFICATIONS MODEL
RECOMMENDED
I
USE*
AC CALIBRATOR OUTPUT LEVEL 1 mV TO 1 OV
FREQUENCY: 20Hz TO 11 OkHz
ACCURACY O.l%@>7mV
FLUKE 5200A
OR EQUIVALENT
PAT
OSCILLOSCOPE > 15MHz BANDWIDTH
A VS B CAPABILITY HP 1740A
PAT
SYNTHESIZER OUTPUT LEVEL 1 mV TO 1 OV HP 3325A
FUNCTION GE
Ic
ERATOR FREQUENCY: 20Hz TO 110kHz P,T
ACCURACY 0.1% @ >7mV
MULTIMETER AC AND DC FUNCTIONS
AC VOLTS: 1V MIN. TO 1OOOV
DC VOLTS: .l V TO 1 OOOV
BALANCED INPUT
HP3455A
PAT
DIGITAL MULTIMETER 1DC CURRENT: 1 AMF’ MAX
I
HP 3466A
I
PAT
DUAL OUTPUT POWER
SUPPLY
[email protected] HP 6234A
DUAL RANGE
DC POWER SUPPLY OdOVdc
@ 0 TO 0.2A HP 6218A
PAT
AUDIO ANALYZER INPUT VOLTAGE RANGE
50mV-300V
BANDWIDTH 500kHz
FILTER 3OkHz
HP 8903A
P
COUNTER RANGE: AC COUPLED 30Hz
TO 100MHz
SENSITIVITY: 1 OmV TO 1 OOMHz
HP 5315A
*P = PERFORMANCE TESTS A = ADJUSTMENTS
T = TROUBLESHOOTING
Table 1-3. List of Parts Used for Performance Tests
PART NUMBER
(IF APPLICABLE) DESCRIPTION
0698-7364
0698-7408
0698-6344
HP 11095A
1250-0781
1251-3757
0493560014
135ohm 1% RESISTOR
6000hm 1% RESISTOR
900ohm 1% RESISTOR
TERMINATION, 6000hm BNC-TO-BNC
BNC-TEE FEMALE
BNC TO TYPE 310 POMONA NO. 2798 OR EQUIVALENT
BNC TO DUAL BANANA JACK POMONA NO. 1296
DUAL BANANA COMPONENT CARRIER POMONA NO. 1
DIAGNOSTIC SERVICE KIT 330-ST

General Information Model 497’,A
t <
l-23. BATTERY OPERATION (Options 001 and 003)
l-24. Nickel-Cadmium batteries enable the 4935A to be used in areas removed from AC power.
Typical operating time is2.5 hrs when fully charged. The batteries are trickle-charged whenever the
instrument is connected to an AC source and the POWER switch is in STBY.
1 -EL Regular discharge-charge cycles are recommended to maintain battery capacity. The instrument
should be operated until batteries are discharged (instrument stops working) then recharged, at least every
30 days. Normal recharge time is about 17 hours. Typical battery life under normal operating conditions
should he at least 100 charge-discharge cycles.
l-26. Charging the Batteries
l-27.
The internal battery pack consists of three rechargeable battery packs (+6V, +156V, and -156V).
These provide typically 2.5 hours of continuous use without recharging. To recharge the battery packs, connect
the HP 4935A to an AC power source and press the power switch to STBY. Normal recharge time is about 17
hours.
I-28. The batteries may be charged at temperatures between 5°C and 4O’C (41°F and 104”F), but have
greater charge capacity if charged between 5’C and 25°C (41°F and 77’F). At temperatures above 25°C
the charge acceptance falls off’ as shown in Figure 1-2. For example, a cell charged at 45°C accepts about
60-70’s of its rated capacity. Temperatures below 5°C cause pressure to build up within the cell as it is
charged, which could result in venting of the cell. This results in a permanent degradation of the battery
capacity due to loss of electrolyte.
l-29. Operating Temperature
I-30. Normal operating temperature of the I-IP 4935A with batteries (options 001 and 003) should be
between -2OOC and +40°C. However, there will be a loss of capacity when operating at the extremes. At low
temperatures, the batteries cannot fully discharge even if they were fully charged at room temperature. At high
temperatures this same effect take place to a lesser degree, in addition to the problem of charge acceptance
previously mentioned.
100% EFFICIENCY
8 U 40 80 120 160 200
CHARGE INPUT (% OF NOMINAL CAPACITY) - O.IC CHARGE RATE
024 G 8 lo 12 14 16 18 20
CHARGING TIME IN HOURS - O.lC CHARGE RATE
Figure 1-2. Charge Acceptance at Various Temperatures
l-6

Installation
SECTION II
INSTALLATION
2-l. INTRODUCTION
2-2. This section contains information on initial inspection, preparation for use, power requirements
antI storagcb and shipment. Table 2-l shows all power cords available.
2-3. INITIAL INSPECTION
2-4. Inspect the shipping container for damage. I“ the container or cushioning material is damaged,
keep it. Check the contents of the shipment for completeness, then check the unit mechanically and
electrically. Refer to Section IV for electrical checks.
2-5. If the unit is mechanically damaged or fails electrical tests, notify the carrier and the nearest HP
officbe (listed at the rear of this manual). Hewlett-Packard will arrange for repair or replacement of the
instrument without waiting for claim settlement.
2-6. PREPARATION FOR USE
Before connecting this instrument to an AC power source, be sure that the rear panel line
module is set to the szme voltage as the AC so_urce and that the correct fuse for that AC
voltage is installedk.BiAmp for 120 Vac<&Q@Amp for 220 Vat).
-
(I A. SC
2-7.
POWER REOlJlk’lENTS
2-8. This instrument requires a power source of 100, 120, 220, or 240 Vat. +5’%-lo%, 48 to 66 Hz
single phase. Power consumption is no more than 25 Vat.
2-9.
LINE VOLTAGE SELECTION
2-10. Figure 2-1 provides instructions for line voltasje selection. Card and fuse are factory installed for
120 Vat operation.
I
PROCEDURE
1. Slide cover door to left (the line power cord
must be disconnected).
2. Rotate FUSE PULL to left. Remove the fuse.
3. Remove the PC board by pulling it out. Select
operating voltage by positioning PC board to
show the desired voltage on top-left side,
4. Reinsert the PC board.
Operatang voltage 1s
shown In module window. 5. Rotate FUSE-PULL back into normal position
and reinsert fuse. Use caution to select correct
fuse value.
I
Figure 2-1. Line Voltage Selection
2-1