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Model 3930A
Multifunction Synthesizer
Service Manual

Contains Operating and Servicing Information
WARRANTY
Keithley Instruments,Inc. warrants this product to be free from defectsin material and workmanship for a period of 1 year from date of
shipment.

Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeablebatteries,
diskettes,and documentation.

During the warranty period, we will, at our option, either repair or replace any product that proves to be defective.

To exercisethis warranty, write or call your local Keithley representative,or contact Keithley headquartersin Cleveland, Ohio. You will
be given prompt assistanceand return instructions. Send the product, transportation prepaid, to the indicated service facility. Repairs
will be made and the product returned, transportation prepaid. Repaired or replacedproducts are warranted for the balanceof the origi-
nal warranty period, or at least 90 days.

LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from product modification without Keithley's expresswritten consent,or misuse of
any product or part. This warranty also does not apply to fuses, software, non-rechargeablebatteries, damagefrom battery leakage, or
problems arising from normal wear or failure to follow instructions.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED HEREIN ARE
BUYER'S SOLE AND EXCLUSIVE REMEDIES.

NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT, INDI-
RECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRUMENTS AND
SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF
SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS OF REMOVAL
AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR DAMAGE TO PROPERTY

Keithley Instruments, Inc. 28775Aurora Road Cleveland,OH 44139 216-248-0400 Fax: 216-248-6168 http://www.keithley.com
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CHINA: Keithley Instruments China Holiday Inn Lido Office Building 404C Beijing, 100004 8610-4362871 Fax: 8610-436616s
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FRANCE: Keithley Instruments SARL BP 60 3 alMe des Garays 91122 Palaiseau CXdex 31-6-0115155 Fax: 31-6-0117726
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GE- Keithley Instruments GmbH Landsberger St&e 65 82110 Germering 49-89-849307-o Fax: 49-89-84930759
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GREAT BRITAIN: Keithley Instruments, Ltd. The Minster 58 Portman Road Reading, Berkshire RG30 lEA* 44-01734-575666 Fax: 44-01734-596469
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ITALY: Keitbley Instruments SRL Viale S. Gimig~~ano 20146Milano 39-2-48303008 Fax: 39-2-48302274
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JAPAN: Keithley Instruments Far East KK Aibido Bldg. 7-20-2 Nishishinjuku Shinjuku-ku, Tokyo 160 81-3-5389-1964 Fax: 81-3-5389-2068
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NETHERLANDS: Keithley Instruments BV* Avelingen West 49 4202 MS Gorinchem. 31-(0)183-635333 Fax: 31-(0)183-630821
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SWITZERLAND: Keithley Instruments SA Kriesbachstrasse 4 8600 Diibendorfe 41-1-8219444 Fax: 41-I-8203081
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TAIWAN: Keithley Instruments Taiwan 1, Ming-Yu First Street Hsinchu, Taiwan, R.O.C. 886-35-778462 Fax: 886-35-778455
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Model 3930A Multifunction Synthesizer
Service Manual

Q 1991, Keithley Instruments, Inc.
Test Instrumentation Group
All rights reserved.
Cleveland, Ohio, U.S.A.
August 1991, First Printing
Document Number: 3930A-902-01 Rev. A
All Keithley product names are trademarks or registered trademarks of Keithley Instruments, Inc.

Other brand and product names are trademarks or registered trader&k of their respective holders.
Safety Precautions

The following safety precautions should be observed before using the Model 3930A Muhifunction Synthesizer and any
associated instruments.

This instzument is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety
precautions required to avoid possible injury. Read over this manual carefully before using the instrument.

Exercise extreme caution when a shock hazard is present at the test circuit. The American National Standards Institute
(ANSI) states that a shock hazard exists when voltage levels greater than 30V rms or 424V peak are present. A good
safety practice is to expect that hazardous voltage is present in any unknown cikuit before measuring.

Inspect the connecting cables and test leads for possible wear, cracks, or breaks before each use.

For maximum safety, do not touch the test cables or any instruments while power is applied to the circuit under test.
Turn off the power and discharge any capacitors before connecting or disconnecting cables from the instrument.

Do not touch any object which could provide a current path to the common side of the circuit under test or power line
(earth) ground. Always make measurements with dry hands while standing on a dry, insulated surface capable of with-
standing the voltage being measured.

Instrumentation and accessories should not be connected to humans.
HOW TO USE THIS MANUAL

Details procedures to verify that the instrument meets
stated specifications.
SECTION 1
Performance Verification

.

Describes basic operating principles for the various cirtits
the Model 3930A.
in SECTION 2
Principles of Operation

Covers fuse replacement, calibration and repair of the instru-
ment, and lists replacement parts.
SECTION 3
Service Information

WARNJNG
The information in this manual is intended for qualified serv-
ice personnel who can recognize possible shock hazards. Do
not attempt these procedures unless you are qualified to do so.
Table of Contents
SECTION 1 - Performance Verification
1.1 INTRODUCTION .............................................................. 1-l
1.2 ENVIRONMENTALCONDITIONS.. ............................................... l-l
1.3 INTTIALCONDlTIONS ......................................................... l-l
1.4 LINEPOWER ................................................................. l-l
1.5 RECOMMENDED TEST EQUIPMENT .............................................. l-l
1.6 VERIEICATIONPROCEDTJEES ................................................... 1-2
1.6.1 Frequency and Duty Cycle Accuracy .............................................. l-2
1.6.2 Amplitude Accuracy .......................................................... l-4
1.6.3 Frequency Response (Sine) ..................................................... l-5
1.6.4 Frequency Response (Triangle, Sawtooth, Square) ..................................... l-7
1.6.5 TotalHmonicDistortion ..................................................... l-8
1.6.6. DC Voltage Accuracy ......................................................... l-9
1.6.7 DCLevel(Square)andDCOffsetError(Sine) ........ . .............................. l-9
1 1.6.8 RiseandFaLlTimes ........................................................... l-9

SECTION 2 - Principles of Operation
2.1 INTRODUCTION .............................................................. 2-l
2.2 BLOCK DIAGRAM ............................................................ 2-l
2.2.1 ControlSection .............................................................. 2-l
2.2.2 Display and Keyboard Section ................................................... 2-l
2.2.3 TriggerSection.. ............................................................ 2-l
2.2.4 Synthesizer Section ........................................................... 2-l
2.2.5 AnalogSection .............................................................. 2-l
2.2.6 Power Supply Section ......................................................... 2-3
2.3 ANALOGCIRCUITDESCRD?TION ................................................ 2-3
2.3.1 Analog Section Block Diagram .................................................. 2-3
2.3.2 D/A Converter .............................................................. 2-3
2.3.3 SquareWaveGenerator ....................................................... 2:3
2.3.4 AmplitudeModulation ........................................................ 2-3
2.3.5 Amplitude and DC Offset Control ................................................ 2-3
2.4 SYN'IHESIZEROl'ERATINGPRINCII'LES .......................................... 2-5

SECTION 3 - Service Information
3.1 INTRODUCTION .............................................................. 3-l
3.2 LINEFLJSEREPLACEMENT ..................................................... 3-l
3.3 CALIBRATION ............................................................... 3-l
3.3.1 EnvironmentalConditions ..................................................... 3-2
3.3.2 InitialConditions ............................................................ 3-2
3.3.3 LinePower ................................................................. 3-2
3.3.4 Recommended Calibration Equipment ................. . ........................... 3-2
3.3.5 Cover Removal .............................................................. 3-3
3.3.6 Calibration Adjustments ....................................................... 3-3
3.3.7 CalibrationProcedures ........................................................ 3-6
3.3.8 Cover Replacement ........................................................... 3-9
3.4 FAN FILTER CLEANING ........................................................ 3-9
3.5 FCTN OTJTJUMPER ........................................................... 3-9
3.6 RECHARGEABLE BATTERY REPLACEMENT ........................................ 3-10
3.7 REPAIR ..................................................................... 3-10
3.7.1 Factory Service .............................................................. 3-10
3.7.2 PowerSupplyTestPoints ...................................................... 3-10
.3.7.3 Board-Level Repair ........................................................... 3-12
3.8 REPLACEABLE PARTS ......................................................... 3-12
3.8.1 Parts List .................................................................. 3-12
3.8.2 Ordering Parts .............................................................. 3-12

APPENDICES
A TypicalData............................................................,..... A-l
B Model3930ASpecifications ...................................................... B-l
List of Illustrations

SECTION 1 - Performance Verification
Figure l-l Connections to Timer/Counter ............................................... l-3
Figure l-2 Connections to Model 197A DMM ............................................ l-4
Figure l-3 Connections to Wideband AC DVM ........................................... l-5
Figure l-4 Co~ections to Audio Analyzer .............................................. l-8

SECTION 2 - Principles of Operation
Figure 2-l Overall Block Diagram ..................................................... 2-2
Figure 2-2 Analog Selection Block Diagram .............................................. 24
Figure 2-3 Frequency Synthesizer Address Generator Diagram ............................... 2-5
Figure 2-4 Address Generator Waveform ............................................... 2-6
Figure 2-5 Waveform Memory and D/A Converter ........................................ 2-6

SECTION 3 - Service Information
Figure 3-l CoverRemoval ........................................................... 3-3
Figure 3-2 Analog Board (NP-21022) Calibration Adjustments ................................ 3-4
Figure 3-3 Control Board (NJ?-10408)Calibration Adjustments ................................ 3-5
Figure 3-4 Co~eciions to Model 197A DMh4 ............................................ 3-6
Figure 3-5 Second Model 3930A Corux!ctions ............................................. 3-7
Figure 3-6 Co~eciions to PM 6654C Counter ............................................ 3-8
Figure 3-7 connections to Dv'M ...................................................... 3-9
Figure 3-8 Power Supply Test Point Locations ............................................. 3-11
Figure 3-9 ExplodedView ........................................................... 3-13

-. -
List of Tables
SECTION 1 - Performance Verification
Table l-l VerificationEquipment ..................................................... l-2
Table l-2 Limits for Frequency and Duty Cycle Accuracy ................................... 13
Table l-3 Limits for Amplitude Accuracy ............................................... l-4
Table l-4 Limits for Frequency Response (Sine) .......................................... l-6
Table l-5 Limits for Frequency Response (Triangle, Sawtooth, Square) ......................... l-7
Table l-6 Limits for Total Harmonic Distortion .......................................... l-8
Table l-7 Limits for DC Voltage Accuracy .............................................. l-9
Table l-8 Limits for DC Level (Square) and DC Offset Error (Sine) ............................ l-9
Table l-9 Limits for Rise/Fall Times ................................................... l-10

SECTION 3 - Service Information
Table 3-l Recommended Line Fuses ................................................... 3-l
Table 3-2 Recommended Test Equipment for Calibration ................................... 3-2
Table 3-3 Power Supply Test Point Summary ............................................ 3-10
Table 3-4 Board Level Repair Summary ................................................ 3-12
Table 3-5 Replaceable Parts ......................................................... 3-12
SECTION 1
Performance Verification

1.1 INTRODUCTION cation procedures. If the instrument has been subject to
extremes of temperature (outside the range specified in
The procedures outlined in this section may be used to the previous paragraph), additional time should be al-
verify that the Model 3930A is operating within the limits lowed for internal temperatures to reach normal operat-
stated in the specifications. Performance verification may ing temperature. Typically, it takes one additional hour
be done when the instrument is first received to ensure to stabilize a unit that is 10