Tektronix 3933A Service Manual

ice

ase

ifte

ontains Servicing Information

Publication Date: August 1991
Document Number: 3933A-902-01 Rev. A

WARRANTY

Keithley Instruments, Inc. warrants this product to be free from defects in 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,
rechargeable batteries, diskettes, and documentation.

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

To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in
Cleveland, Ohio. You will be given prompt assistance and return instructions. Send the product, transporta­tion prepaid, to the indicated service facility. Repairs will be made and the product returned, transportation
prepaid. Repaired or replaced products are warranted for the balance of the original warranty period, or at
least 90 days.

LIMITATION OF WARRANTY

This warranty does not apply to defects resulting from product modification without Keithley’s express writ­ten consent, or misuse of any product or part. This warranty also does not apply to fuses, software, non-re­chargeable batteries, damage from battery leakage, or problems arising from normal wear or failure to follow
instructions.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANT

IES, EXPRESSED OR IMPLIED, INCLUDING
ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE
REMEDIES PROVIDED HEREIN ARE BUYERS SOLE AND EXCLUSIVE REMEDIES.

NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR
ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQ

UENTIAL 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.

Instruments Division, Keithley Instruments, Inc. l 28775 Aurora Road l Cleveland, Ohio 44139 l [phone] l Fax: [phone]

WEST GERMANY:
GREAT BRITAIN: Keithley Instruments, Ltd. . The Miner l 58, Portman Road l Reading, Lkerkshire RG 3 IEA l 01144 734 575 666 l Fax: [phone]
FRANCE Keitbley Instruments SARL l 3 Allee des Garays l B.P. 60 l 91lZ4 Palalseau/Z.L l 1-6-0115 155 l Telex: 600 933 l Fax I-6-0117726
NEIXERLANDS: Keithley Instruments BV . Avelingen West 49 l 4202 MS Gorinchem l P.O. Box 559 l 4200 AN Gorinchem .0X+30-35333 l Telex 24 684 l Fax [phone]
SWITZERLAND: Keitbley Instruments SA . Kriesbachstr. 4 l 8600 Dubendorf l 01-821-9444 l T&x 828 472. Fax: [phone]
AUSTRIA: Keitbley Instruments GesmbH . Rosenhugelshasse 12 l A-1120 Vienna l (027.2) 84 65 45. Telex: I31677 l Fax: [phone]
ITALY: Keithley Instruments SRL l Vi&S. Gimignano 4/A. 20146 Milano. 02-4120360 or 02-4156540 l Fax: [phone]

Keithley Instruments GmbH l Heiglhofstr. 5 l Munchen 70 l OSY-7IOOZ-O l Telex 52-12160 l Fax: [phone]

Service Manual

Model 3933A
Phase Shifter

01991, Keithley Instruments, Inc.

All Rights Reserved

Instruments Division

Cleveland, Ohio, U. S. A.

Document Number: 3933A-902-01

All Keithley product names are trademarks or registered trademarks qf Keithley Instruments, Inc.
Other brand and product names are trademarks or registeredLtrademarks of their respective holders.

r. . *

Safety Precautions

The following safety precautions should be observed before using the Model 3933A Phase Shifter and any associated
instruments.

This instrument 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 42.4V peak are present. A good

safety practice is to expect that hazardous voltage is present in any unknown circuit 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.

Describes basic operating principles for the various circuits in
the Model 3933A.

Covers fuse replacement, calibration and repair of the instru­ment, and lists replacement parts.

WARNING

The information in this manual is intended for qualified serv­ice personnel who can recognize possible shock hazards. Do
not attempt these procedures unless you are qualified to do so.

SECTION 1

Performance

Verification

SECTION 2

Principles of Operation

SECTION 3

Service Information

Table of Contents

SECTION 1

1.1

1.2 ENVIRONMENTAL CONDITIONS ................................................

1.3

1.4 LINEPOWER .................................................................

1.5

1.6

1.6.1

1.6.2 Frequency and Duty Cycle Accuracy

1.6.3 Amplitude Accuracy ..........................................................

1.6.4

1.6.5

1.6.6

1.6.7.

1.6.8

1.6.9

- Performance Verification

INTRODUCTION ..............................................................

INITIAL CONDITIONS .........................................................

RECOMMENDED TEST EQUIPMENT
VERIFICATION PROCEDURES

SynthesizerConnections .......................................................

FrequencyResponse(Sine)
Frequency Response (Triangle, Sawtooth, Square)
Total Harmonic Distortion
DCVoltageAccuracy
DC Level (Square) and DC Offset Error (Sine)
RiseandFallTimes

...........................................................

.....................................................

.....................................................

.........................................................

..............................................

...................................................

..............................................

....................................

.......................................

SECTION 2 - Principles of Operation

2.1

2.2

2.2.1

2.2.2

2.2.3

2.2.4

2.2.5

2.3

2.3.1

2.3.2

2.3.3

2.3.4

2.3.5

2.4

INTRODUCTION.

BLOCKDIAGRAM ............................................................

Control Section
Display and Keyboard Section
Phase Shift Section
Analog Section
PowerSupplySection

ANALOG CIRCUIT DESCRIPTION

Analog Section Block Diagram
D/A Converter
Square Wave Generator
AmplitudeModulation
Amplitude and DC Offset Control

MULTIPHASE OSCILLATOR OPERATION

.............................................................

..............................................................

...................................................

...........................................................

..............................................................

.........................................................

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l-l
l-l
l-l
l-l
l-l
1-2
1-2
l-3
1-4
1-6
1-8
1-9
l-10
l-10
l-10

2-l
2-l
2-1
2-l
2-l
2-1
2-3
2-3
2-3
2-3
2-3
2-3
2-3
2-3

SECTION 3 - Service Information

3.1

3.2

3.3

3.3.1

3.3.2

3.3.3

INTRODUCTION

LINE FUSE REPLACEMENT .....................................................

CALIBRATION

Environmental Conditions
Initial Conditions
LinePower

..............................................................

...............................................................

.....................................................

............................................................

.................................................................

3-1
3-1
3-1
3-2
3-2
3-2

3.3.4

3.3.5

3.3.6

3.3.7

3.3.8

3.3.9

3.4

3.5

3.6

3.7

3.7.1

3.7.2

3.7.3

3.8

3.8.1

3.8.2

Recommended Calibration Equipment
CoverRemoval
CalibrationAdjustments
Function Synthesizer Connections
CalibrationProcedures

Cover Replacement
FANFILTERCLEANING
FCTNOUTJUMPER
RECHARGEABLE BATTERY REPLACEMENT
REPAIR

Factory Service

Power Supply Test Points

Board-levelRepair

REPLACEABLEPARTS .........................................................

PartsList

Ordering Parts ..............................................................

APPENDICES

............................................

........... ..;

.......................................................

........................................................

...........................................................

........................................................

...........................................................

.....................................................................

...............................................................

......................................................

...........................................................

..................................................................

.........

................................................

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........................................

s .I .,

3-2
3-3
3-3
3-5
3-5
3-8
3-9
3-9
3-9
3-9
3-9
3-10
3-10
3-10
3-10
3-10

A
B

Typical Data
Model 3933A Specifications

List of Illustrations

SECTION I- Performance Verification

Figure l-1 Connections Between Model 3933A and Model 3930A Multifunction Synthesizer
Figure l-2 Connections to Timer/Counter
Figure l-3
Figure l-4 Connections to Wideband AC DVM
Figure l-5 Connections to Audio Analyzer

Connections to Model 197A DMM

...............................................

............................................

...........................................

..............................................

SECTION 2 - Principles of Operation

Figure 2-1
Figure 2-2 Analog Section Block Diagram
Figure 2-3

Overall Block Diagram

Multiphase Oscillator Block Diagram

.....................................................

...............................................

..........................................

SECTION 3 - Service Information

Figure 3-l Cover Removal
Figure 3-2 Analog Board (NE-21022) Calibration Adjustments
Figure 3-3
Figure 3-4
Figure 3-5
Figure 3-6
Figure 3-7
Figure 3-8
Figure 3-9

Function Synthesizer Connections
Connections to Model 197A DMM
Second Model 3930A Connections
Connections to PM6654C Counter
Connections to Wideband AC DVM
Power Supply Test Point Locations
Model 3933A Exploded View

...........................................................

................................ 3-4

.............................................

............................................ 3-5

.............................................

.............................................

...........................................

............................................

................................................

.........

l-2
l-3

1-4
1-6
1-9

2-2
2-4
2-5

3-3

3-5

3-6
3-7
3-8
3-11
3-12

List of Tables

SECTION 1 - Performance Verification

Table 1-l Verification Equipment
Table 1-2 Limits for Frequency and Duty Cycle Accuracy
Table 1-3
Table l-4 Limits for Frequency Response (Sine)
Table 1-5
Table l-6
Table l-7
Table l-8
Table l-9

Limits for Amplitude Accuracy

Limits for Frequency Response (Triangle, Sawtooth, Square)
Limits for Total Harmonic Distortion
Limits for DC Voltage Accuracy
Limits for DC Level (Square) and DC Offset Error (Sine)
Limits for Rise/Fall Times

.....................................................

...............................................

..........................................

..........................................

..............................................

...................................................

SECTION 3 - Service Information

Table 3-1
Table 3-2
Table 3-3
Table 3-4
Table 3-5

Recommended Line Fuses

Recommended Test Equipment for Calibration
Power Supply Test Point Summary
BoardLevelRepairSummary
Replaceable Parts

.........................................................

...................................................

............................................

................................................

...................................

.........................

............................

...................................

l-2
l-3
l-5
1-7
l-8
1-9
l-10
l-10
l-11

3-1
3-2
3-10
3-10
3-13

SECTION 1

Performance Verification

1 .I INTRODUCTION

The procedures outlined in this section may be used to
verify that the Model 3933A is operating within the limits
stated in the specifications. Performance verification may
be done when the instrument is first received to ensure
that no damage or misadjustment has occurred during
shipment. Verification may also be performed whenever
there is a question of instrument accuracy, or following
calibration, if desired.

NOTE
If the instrument is still under warranty (less
than one year from the date of shipment), and
its performance falls outside the specified
range, contact your Keithley representative or
the factory to determine the correct course of
action.

1.2 ENVIRONMENTAL CONDITIONS

All measurements should be made at 18-28OC (65-82°F)
and at less than 70% relative humidity.

1.3 INITIAL CONDITIONS

cation procedures. If the instrument has been subjected
to extremes of temperature (outside the range specified
in the previous paragraph), additional time should be al­lowed for internal temperatures to reach normal operat­ing temperature. Typically, it takes one additional hour
to stabilize a tit that is 10°C (18°F) outside the specified
temperature range.

1.4 LINE POWER

Be sure to set the line voltage switch for the correct volt-

age. The instnunent should be operated at a voltage
within&lo% of the line voltage setting and at a frequency
from 48 to 62Hz.

1.5 RECOMMENDED TEST EQUIPMENT

Table l-l lists all the test equipment needed for verifica­tion. The procedure for performance verification is based
on using this exact equipment.

NOTE
The verification limits reflect only the accu­racy specifications of the Model 3933A. They
do not include test equipment tolerance.

The Model 3933A must be turned on and allowed to
warm up for at least one hour before beginning the verifi-

Alternate equipment may be used as long as the substi­tute equipment has specifications at least as good as

l-l

SECTION 1
Performance Verification

Table l-1. Verification Equipment

Manufacturer
Keithley
Keithley
Fluke
Philips
Panasonic
Keithley
Keithley

Pomona

those listed in Table l-l (except for the Model 3930A

Multifunction Synthesizer, which is required in all cases>.

Model
3930A
197A
8920A
PM 6654C

PM 9678
VP-7722A

7051-2
7755
1468

Description Specifications
Multifunction Synthesizer
DMM (DC volts, AC volts)

(5-l /2 digits)
DVM (AC volts)
(3-l /2 digits)
Timer/Counter
TCXO option
Audio Analyzer

BNC Interconnect Cable
5OQ Feed-through Terminator
BNC-banana Adapter

1.6 VERIFICATION PROCEDURES

0. 1mHz to 1.2MHz; k5ppm
20V range; f(0.015% of rdg + 3 counts)

ACV; f(0.35% of rdg + 100 counts)
20V range; lkHz-2OOlcHz (0.5% of rdg),
2OOkHz-1MHz (0.7%), l-1OMHz (3%), lo-20MHz (5%)
O.OlHz-12OMHz; time base aging
<l x 10-7/month; Vp-p measurements
IOHz-1lOkI-k; 0.001% at full scale; fldB harmonic dis­tortion accuracy from 1OHz to 15.99kHz
5OQ coaxial cable (RG-58C), male BNC connectors, 2ft
(0.6m)
BNC to BNC adapter, 500 termination, DC to
25OMHz, VSWR of <l.l
Female BNC connector to double banana plug

1.6.1

The Model 3933A must be tested in conjunction with a
Model 3930A Mutlifunction Synthesizer. Figure l-1
shows DIGITAL OUT/DIGmAL IN in connections using
the CA-94 cable supplied with the Model 3933A. Note
that frequency is set on the Model 3930A Synthesizer.

Synthesizer Connections

The following paragraphs contain the detailed proce­dures for verifying the accuracy specifications of the
Model 3933A using the equipment listed in Table 1-l.
The allowable reading limits in these procedures do not
include error that could be contributed by this equip­ment.

These procedures are intended for use only by qualified
personnel using accurate and reliable test equipment. If
the instrument is out of specifications and not under war­ranty, refer to the calibration information in Section 3.

CA-94 Dinital Cable

Model 3930A Synthesizer Model 3933A Being Tested

1

Figure I-I.

Connections Between Model 3933A and

Model 3930A Multifunction Svnthesizer

l-2

Performance Verification

SECTION 2

1.6.2

Frequency and Duty Cycle

Accuracy

1. Connect the phase shifter to the Model 3930A and a
timer/counter as shown in Figure 1-2. Turn on all in­struments.

2. Restore factory defaults on the Model 3933A by
pressing SHIFT PRST.

3. Program a frequency on the Model 3930A. Set the
Model 3933A for the sine function with an amplitude

CA-94 Digital Cable

I

L

4. Set the timer/counter to display the frequency at
Channel A, and verify that the frequency reading is
within the limits specified in Table l-2.

5. Program a Model 3930A frequency of 1OOHz. Set the
Model 3933A for a square wave with 50% fixed duty
cycle.

6. Set the timer/counter to display the pulse width of
Channel A, and verify that the reading is within
specifications shown in Table 1-2.

7. Modify the frequency and duty cycle settings of the

phase

shifter and synthesizer according to Table 1-2,

*and verify the pulse width readings.

Model PM 6654C Timer/Counter

- of 2ovp-p.

Model 3930A

Synthesizer

Figure 1-2. Connecfions to Timer/Counter

Table l-2. Limits for Frequency and Duty Cycle Accuracy

3933A
Function

Sine
Square (FXD50)

Square (VAR50)

3933A 3930A

Amplitude Frequency
2ovp-p
2ovp-p

2ovp-p

Being Tested

Function Output

Allowable Timer/

Counter Reading

1MHZ
1OOHz

1kHz
5kHz
1OkHZ

999.995kHz to 1.000005MHz

4.97msec to 5.03msec
497psec to

99.4psec to

49.7psec to 50.3psec

1OOHz 4.98msec to
1kHz 498pec
5kHz

99.6psec to

1OkHz 49.8psec to

(18°c to 28OC)

503psec

100.6pec

5.02msec

to

502psec

100.4psec

50.2psec

50R impedance.

NOTE: Frequency accuracy is determined by the Model 3930A Multifunction Synthesizer.

l-3

SECTION 1

Performance Verification

1.6.3

1. Connect the phase shifter to a DMM ‘as shown in

2. Restore factory defaults on the Model 3933A by

Amplitude Accuracy

Figure 1-3. Turn on all instruments.
pressing SHIFT RRST.

CA-94 Digital Cable

Model 3930A

Synthesizer

Model 3933A
Being Tested

3. Program a 1kHz frequency on the Model 3930A. Set
the Model 3933A for the sine function with an ampli­tude of 7.49Vp-p.

4. Set the DMM to measure AC volts with autoranging,
and verify that the voltage reading is within the lim-

its specified in Table 1-3.

5. Change the function, frequency, and amplitude set­tings of the phase shifter and synthesizer according
to Table 1-3 and verify the voltage readings.

Pomona 1468

Connect shield

\

Function Output

Figure l-3.

Connections to Model 197A DMM

l-4

Table 1-3. Limits for Amplitude Accuracy

Performance Verification

SECTION 1

39334 3933A
Function

Sine
Square (FXD50) 3.558Vrms to
Triangle 2.0541Vrms to 2.1837Vrm.s
Sawtooth Up
Sawtooth Down

Sine

Sine lOVp-p

Sine

Triangle
Square
Sawtooth Up
Sawtooth Down

Amplitude

7.49vp-p lkl%

3ovp-p

3VP-P

3ovp-p

3930A
Frequency

1kHZ
1okHz 10.5536Vrms to
20kHz
5okHz 10.5536Vrms to

1kHz 3.5179vrms to
1okHz 3.5179vrms to
2okHz
5okHz 3.5179vrms to

lk?IZ
1okHz
20kHz
5OkHz

1kHz

Allowable DMM Reading

(18°C to 28’C)

2.6349Vrms to 2.6613Vrms

3.782Vrms

2.0541Vrms to 2.1837Vrms

2.0541Vrms to 2.1837Vrms

10.5536Vrms to 10.6596Vrms

10.6596Vrms

10.5536Vrms to 10.6596Vrms

10.6596Vrms

3.5532Vrms

3.5532Vrms

3.5179vrms to 3.5532Vrms

3.5532Vrms

1.05536Vrms to

1.05536Vrms to 1.06596Vrms

1.05536Vrms to 1.06596Vrms

1.05536Vrms to

8.617OVrms to

14.25vrms to 15.15vrms

8.6170Vrms to 8.7468Vrms

8.617OVrms to 8.7468Vrms

1.06596Vrms

1.06596Vrms

8.7468Vrms

1-5

SECTION I

Performance Verification

1.6.4

Frequency Response (Sine)

1. Connect the phase shifter to the Model 3930A and a
wideband AC DVM as shown in Figure l-4. Turn on
all instruments.

2. Restore factory defaults on the Model 3933A by
pressing SHIFT PRST.

3. Program a 1kHz Model 3930A frequency and a
Model 3933A sine function of 3OVp-p.

4. Set the DVM to measure AC volts with autoranging,
and verify that the voltage reading is within the lim­its specified in Table 1-4.

Set the DVM to measure dB, and select a 5012 refer-

5.
ence impedance. Press REL to establish the present
voltage reading as the relative dB reference.
Change the frequency setting of the synthesizer ac-

6.
cording to Table l-4, and verify the subsequent fdB

readings.

7.

Program a 1kHz sine function of 3.75Vp-p, and ver­ify that the voltage reading is within limits. Press
REL to establish the reading as the relative dB refer­ence. Verify the fdB readings for the remaining fre­quencies.
Program a 1kHz sine function of 3.74Vp-p,

8.

and ver-

ify the reading. Establish the present reading as the
relative dB reference. Verify the fdB readings for the
remaining frequencies.

CA-94 Digital Cable

*Model 3930A

Synthesizer

1 Fiwre 1-4. Connectiom to Wideband AC DVM

Model 3933A
Being Tested

Model 7755

---

\

Function Output

8920A Voltmeter

lel
c

-

lode1 7051-2 Coaxial Cable

M

l-6

Performance Verification

SECTION 1

Table 1-4.

3933A
Function

Sine

3933A
Amplitude

3ovp-p

Sine 3.75vp-p

Limits for Frequency Response (Sine)

3930A
Frequency

1kHz
1OkHz
1ookHz
2ookHz
350kHz
5ookHz
7ookHz
8OOkHz
9ookHz
1MHz

1.2MHz
1kHZ

1OkHz
1ookHz
2ookHz
350kHz
5ookHz
7ookHz
8OOkHz
9ookHz
1MHz

1.2MHz

Allowable Voltmeter Reading

(18T to 28’C)

5.2Vrms to 5.4Vrms (=REZ)

-0.ldB to +O.ldB

-O.ldB

to +O.ldB

-0.3dB to

-0.3dB to

-0.3dB to

-0.3dB to

-0.5dB

to

-0.5dB to

-0.5dB to

-1 .OdB to

0.65Vrms to

-O.ldB to

-O.ldB

to +O.ldB

-0.3dB to

-0.3dB to

-0.3dB to

-0.3dB to

-0.5dB

-0.5dB

to
to

-0.5dB to

-l.OdB to

+0.3dB
+0.3dB
+0.3dB
+0.3dB
+0.3dB
+0.3dB
+0,3dB
+0.3dB

0.676Vrms (=REF,J
+O.ldB

+0.3dB
+0.3dB
+0.3dB
+0.3dB
+0.3dB
+0.3dB
+0.3dB
+0.3dB

Sine

3.74vp-p 1kHz
1okHz
1ookHz

2ookHz

350kHz

5ookHz

7ookHz
8OOkHz

9ookHz

1MHz

1.2MHz

0.648Vrms to

-O.ldB to

-O.ldB to

-0.3dB to

-0.3dB to

-0.3dB to

-0.3dB to

-0.5dB

to

-0.5dB to

-0.5dB to

-l.OdB to

0.674Vrms (=REF)
+O.ldB
+O.ldB
+0.3dB
+0.3dB
+0.3dB
+0.3dB
+0.3dB
+0.3dB
+0.3dB
+0.3dB

l-7

SECTION 2

Performance

Verification

1.6.5 Frequency Response (Triangle,
Sawtooth, Square)

1. Connect the phase shifter to the synthesizer and a
timer/counter as shown in Figure l-2. Turn on ah in­struments.

2. Restore factory defaults on the Model 3933A by
pressing SHIFT PRST.

3. Program a 1kHz Model 3930A frequency and a
Model 3933A triangle wave of 3OVp-p.

Table 1-5. Limits for Frequency Response (Triangle, Sawtooth, Square)

3933A 3933A
Function Amplitude

Triangle

3ovp-p

Sawtooth Up 3ovp-p

3930A

Frequency
1kHz

5kHz
1okHz

1kHZ
5kHz

1okHz 0.95 xREiF to 1.05 x REF

4. Set the timer/counter to display the peak-to-peak
voltage at Channel A, and verify that the voltage
reading is within the limits specified in Table l-5.
Call this reading REF.

5. Change the synthesizer frequency to 5kHz. The new
reading should be between 0.97 times the REF read­ing and 1.03 times the REF reading.

6. Modify the frequency and function settings of the

synthesizer and phase shifter according to Table l-5,
and verify that the corresponding readings are
within the specified limits.

Allowable Timer/Counter Reading

(18°C to 28°C)

14.25Vp-p to

15.75Vp-p (=REF)

0.97xREF to 1.03 x REF

0.97xREF to 1.03 x RRF

14.25Vp-p to 15.75vp-p (=REF)

0.95 xREF to

1.05

x REF

Sawtooth Down 3ovp-p

Square t

3ovp-p

1kHZ

1425vp-p to

15.75vp-p (=REF)
5kJ3z 0.95 xREF to 1.05 x REF
1OkHz 0.95 xREF to 1.05 x RRF

1kHZ
5kHz

1425vp-p to 15.75vp-p (=REF)

0.98 xREF to

1.02xRRF
1okHz 0.98 xRRF to 1.02 x RRF
100kHz 0.98 xREF to 1.02 x REF

1-8

Performance Verification

SECTTON 1

1.6.6

1. Connect the phase shifter to the synthesizer and an

2. Restore factory defaults on the Model 3933A by

3. Program a 1kHz Model 3930A frequency and a

4. Set the audio analyzer to measure distortion, and

5. Change the frequency setting of the synthesizer ac-

Total Harmonic Distortion

audio analyzer as shown in Figure l-5. Turn on all
instruments.

pressing SHIFT PRST.
Model 3933A sine function of SOVp-p.
verify that the reading is within the limits specified

in Table l-6.
cording to Table l-6, and verify the distortion read-

ings.

CA-94 Digital Cable

Diaital Diaital

I

OCT

I/

Table 1-6. Limits for Total Harmonic Distor-

tion

I I I

3933A
Function

Sine

3933A
Amplitude Frequency

3ovp-p

L

Model VP-7722A Audio Analyzer

I

-====l

1 3930A 1 g$c 1

1kHz < 0.1%
1okHz < 0.1%
20kHz
35kHz

5okHz
7okHz

1OOkHz

1 Allowable 1

(18T to 28’C)

< 0.1%
< 0.1%
< 0.1%
< 0.1%
< 0.1%

L

Figure l-5.

Model 3930A

Synthesizer

Connections to Audio Analyzer

Model 3933A
Being Tested

- 5;MFq?dgB6 E:ugh

Model 7051-2 Coaxial Cable

\

Function Output

Note: Put FLT Switch

in ground position

1-9

SECZ7ON
Performance Verification

1

1.6.7.

1. Connect the phase shifter to the synthesizer and a

2. Restore factory defaults on the Model 3933A by

3. Program the Model 3933A for the DC function,

4. Set the DMM to measure DC volts with autoranging,

5. Change the offset setting of the phase shifter accord-

Table 1-7.

3933A
Function

DC

DC Voltage Accuracy

DMM as shown in Figure 1-3. Turn on all instm­ments.

pressing SHIRT PRST.

2.OOmV amplitude, with +15V offset.
and verify that the voltage reading is within the lim-

its specified in Table 1-7.
ing to Table 1-7, and verify the subsequent voltage

readings.

Limits for DC Voltage Accuracy

3933A
Offset (ltw to 28W

+15v +14.842V to +15.158V

-15v
+5v

-5V
+1.5v

-1.5v

Allowable DMM Reading

I

-14.842V to -15.158V
t4.942V to +5.058V

-4.942V to -5.058V
+1.477V to +1.523v

-1.477V to -1.523V

1.6.8 DC Level (Square) and DC Offset
Error (Sine)

1. Connect the phase shifter to the synthesizer and a
DMM as shown in Figure l-3. Turn on all instru­ments.

2. Restore factory defaults on the Model 3933A by
pressing SHIFT PRST.

3. Set the Model 3933A for a 7.49Vp-p square wave
with a phase setting of +90°. Set the Model 3930A for

gated mode and the EXT %. trigger source.

4. Set the DMM to measure DC volts with autoranging,

and verify that the voltage reading is within the lim­its specified in Table l-8.

5. Change the function, amplitude, mode, trigger

source, and phase settings of the phase shifter and
synthesizer according to Table l-8 and verify the
voltage readings.

1.6.9

1. Connect the phase shifter to the synthesizer and a

2. Restore factory defaults on the Model 3933A by

3. Program a 1OOkHz square wave (FXD50) of SOVp-p.

4. Set the timer/counter to measure rise/fall times of

5. Change the amplitude setting of the phase shifter ac-

Rise and Fall Times

timer/counter as shown in Figure l-l. Turn on all in­struments.

pressing SHIFT PRST.

Channel A and verify that the rise time is within the
limit specified in Table l-9. Then change the slope to
measure the fall time and verify the reading.

cording to Table l-9, and verify the remaining rise/
fall times.

l-10

Table l-8. Limits for DC Level (Square) and DC Offset Error (Sine)

3930A
3933A 3933A
Function

Square

Sine 3ovp-p

Amplitude Mode

7.49vp-p

3vp-p

3930A Trigger

Source

Gate Ext 1

Gate Ext% 0"

3933A
Phase

+90”

-90”

Allowable DMM Reading

(l&l°C to 28°C)

3.715v to 3.774v

-3.715v to -3.774v
&68mV

+14mV

Table 1-9. Limits for Rise/Fall Times

“‘“W;~~~;~“’ 1

3.75vp-p

3.74vp-p

Performance Verification

SECTION 2

< 150nsec
c 150nsec
< 150nsec
< 150nsec
< 150nsec
< 150nsec

SECT10

Principles of Operation

2.1 INTRODUCTION

This section covers basic operating principles of the

Model 3933A.

2.2 BLOCK DIAGRAM

Figure 2-l shows an overall block diagram of the Model

3933A. The various sections include the control section,

display and keyboard section, phase shift section, digital
I/O section, analog section, and the power supply and
GPIB interface sections.

2.2.1 Control Section

The control section supervises all instrument operations.
The control section includes the 68008 microprocessor,

EPROM for program storage, and battery backed-up
RAM for working storage and memory to store operating
parameters.

2.2.2 Display and Keyboard Section

This section includes a 40-character X 2-line LCD (liquid
crystal display) and a membrane keyboard. The LCD is
backlit for better visibility.

2.2.3 Phase Shift Section

This section produces digital waveform data by phase
shifting the signal from the Model 3930A Synthesizer or
another Model 3933A Phase Shifter. Key parts of the
phase shift section include the phase shift addition cir­cuit, sine wave conversion ROM, sweep I/O circuits, and
the digital output circuits to provide the necessary sig­nals for any additional Model 3933A Phase Shifters.

2.2.4

The analog section includes a D/A converter to convert
digital waveform data produced by the phase shift sec­tion into the analog output signal. The analog section also
controls the amplitude of the output waveform and adds
the DC offset to the output signal.

The analog section is isolated from other parts of the digi­tal system by a pulse transformer and photo coupler.

Analog Section

2-l

SECTION 2

Principles of Operation

GPIB

Interface

Block

-1

Control

Block

Synthe-

sizer

Block

From

t+

l-0

From Other

3933A 3930A

DIGITAL OUT DIGITAL OUT

------

------

[ DIGITAL :

OUT 1

L

------

------

0

~HOLDIN 1

-_---_--

------

0 bYNCOUTj

-------_

Figure 2-1.

l-----1

1 GPIB 1
I----,

Overall Block Diagram

----------

To Analog Block

/ / q--@pEm

-I

0 Front panel connector

2-2

Principles

SECTION 2

of

Operation

2.2.5

The power supply provides several DC operating volt­ages to various other sections in the instrument and is
made up of a transformer and series regulators. Supply
voltages include ti4V, HSV, and two +5V DC supplies.

Note that power supply common for all circuits except
the analog section is connected to chassis ground. Analog
common is connected to chassis ground through a
varistor.

Power Supply Section

2.3 ANALOG CIRCUIT DESCRIPTION

2.3.1

Figure 2-2 shows a block diagram of the analog section of
the instrument. Key sections include the D/A converter,
square wave generator, amplitude modulation circuits,
and multiplying D/A and attenuator for amplitude and
DC offset control.

2.3.2

Digital waveform data isconverted into an analog signal
by the D/A converter. The converted signal is then
passed through a low-pass filter to remove any spurious
components. This conversion process is used to generate
sine, triangular, and sawtooth waves.

&alog Section Block Diagram

D/A Converter

2.3.3 Square Wave Generator

Square waves with fixed 50% duty cycle are generated by
applying sine waves to an analog comparator. The ana­log comparator has a certain amount of hysteresis, which
results in good-quality square waves at the output.

is applied to the AM multiplier, which performs the
modulating function.

2.3.5

Control of the AC amplitude and DC offset amplitude is
performed the multiplying D/A section in conjunction
with the output amplifier. Further amplitude control is
provided by the output attenuator, which includes 1:lO
and 1:lOO attenuation ratios. Combining these two ratios
yields overall attenuation ratios of l:l, l:lO, l:lOO, and

1:lOOO.

Amplitude and DC Offset Control

2.4 MULTIPHASE OSCILLATOR

OPERATION

Figure 23 shows a block diagram of a multiphase oscilla­tor made up of a Model 3930A Multifunction Synthesizer
and two Model 3933A Phase Shifters. In this multiphase
oscillator, the output of the Model 3930A is assigned as
the first phase, while the second and third phase outputs
are outputs from the two phase shifters as shown. In this
manner, a multiphase oscillator up to a maximum of six
phases can be configured. The oscillating frequency and
oscillation mode for all units are determined by the main
synthesizer signal, but the phase, amplitude, DC offset,
and waveform type can be independently programmed
for each unit.

Note that the main synthesizer signal, which provides a
reference phase for each unit, is not directly output, and
that the phase of each unit can be set independently of the
others. Also note that the first phase signal (Model 3930
FCTN OUT) is determined by the programmed start/
stop phase of the Model 393OA, while the second and
third phase signals are determined by the phase settings
of those units.

Variable duty cycle square waves are generated by a digi­tal comparator. Digital sawtooth waveform information
is used as the input signal to the digital comparator.

2.3.4

A signal applied to the AM IN jack can be used to ampli­tude modulate the output signal. This modulating signal

Amplitude Modulation

The phases of the various units can be determined from
the programmed phase values (start/stop phase for the
Model 393OA, phase setting for the Model 3933A). For ex­ample, if the Model 3930A start/stop phase is set to 0”,
the Model 3933A phases are simply the programmed val­ues. When the Model 3930A is set to the burst or gate os­cillation modes, the start/stop phase of the synthesizer is
0”. Therefore, the Model 3933A signal phases will aIways
be the same as the programmed phase values when the
burst or gate oscillation mode is used.

2-3

SECTION 2

Principles of Operation

*

Wave

nPta

I I

r

I \ A

, 1 II

“1

In’- TTL VI

i-l- Duty Variable

­>

*

M l-l

V

Multiplier

AM

2%

.-

A \I

1 \

I

A--

^. .

I

Functior

AM ON/OFF

I

‘igure 2-2.

2-4

’ fl5V max/OPEN

Control

Data

Analog Section Block Diagram

Principles of Operation

SECTION2

Frequency
Oscillation mode (Start/Stop) phase

Amplitude, DC

Oscillator

Svnthesizer main sianal

Phase

i -

Phase

offset, waveform control

Amplitude, DC

offset, waveform control

Amplitude, DC
offset, waveform control

H-

3930A Synthesizer

* FCTN (1st phase)

output

3933A Phase Shifter

FCTN (2nd phase)
output

3933A Phase Shifter

) FCTN (3rd phase)

output

Figure 23.

Multiphase Oscillator Block Diagram

I

2-5

SECTION 3

Service Information

3.1 INTRODUCTION

This section contains information on fuse replacement,
instrument calibration and repair, and replacement parts

for the Model 3933A.

3.2 LINE FUSE REPLACEMENT

WARNING
Disconnect the line cord and all other equip­ment from the instrument before replacing
the line fuse.

The line fuse, which is located on the rear panel, protects
the power line input from excessive current. To replace
the fuse, first unplug the line cord, then unscrew the fuse
from its fuse holder. Replace the fuse only with the type
recommended in Table 3-1.

CAUTION
Using the wrong fuse type may result in in­strument damage.

3.3 CALIBRATION

The following paragraphs give step-by-step procedures
for calibrating the Model 3933A. This calibration proce-

Table 3-1. Recommended Line Fuses

Keithley

Line Voltage

100v/120v

22OV/24OV

dure can be performed at specified intervals, or if the per­formance verification procedures covered in Section 1
show that instrument performance is not within specifi­cations.

Calibration must be performed in the se­quence covered below. If any of the calibra­tion procedures cannot be performed success­fully, refer to the repair information in para­graph 3.7 unless the unit is still under war­ranty. (Units still under warranty should be
returned to the factory or authorized repair fa­cility for repair.)

Description

NOTE

Part No.

I

I

3-l

SECTION 3

Service Information

3.3.1

Calibration should be performed at 18-28°C (65-82°F)
and at less than 70% relative humidity.

Environmental Conditions

3.3.2 Initial Conditions

The Model 3933A and the test equipment should be

turned on and allowed to warm up for one hour before
calibration. If the instrument has been subjected to ex­treme temperature or humidity, allow additional time for

stabilization.

Table 3-2. Recommended Test Equipment for Calibration

Manufacturer Model
Keithley

3930A

Description

Multifunction Synthesizer
(2 required)

3.3.3 Llne Power

Before calibrating the instrument, be sure the rear panel
line voltage is set to the correct operating voltage. The
Model 3933A should be calibrated while operating at a
line voltage within flO% of the line voltage switch setting
and at a line frequency from 48Hz to 62Hz.

3.3.4 Recommended Calibratlon
Equipment

Table 3-2 summarizes recommended equipment for cali­brating the Model 3933A. Similar equipment may be
used as long as corresponding specifications are compa­rable.

Specifications

O.lmHz to 12MHz; &5ppm

Keithley 197A

Fluke 8920A

Philips

Keithley

Keithley 7755

Pomona 1468

PM6654C
PM9678

7051-2

DMM (DC volts, AC volts)
(5-l /2 digits)

DVM (AC volts) (3-l /2 digits)

Timer/Counter
TCXO option

BNC Interconnect Cable
(2 required)

5OQ Feed-through Terminator

BNC-banana Adapter

20V range; rt(O.OlS% of rdg + 3 counts)
ACV; +(0.35% of rdg + 100 counts)

20V range; lkHz-200kHz (0.5% of rdg), 2OOkHz­1MHz (0.7%), l-1oMHz (3%), lo-2oMHz (5%)

O.OlHz-12OMHz; time base aging
<l x 10-‘/month; Vp-p measurements

5OQ coaxial cable (RG-58C), male BNC connectors,
2ft (0.6m)

BNC to BNC adapter, 50R termination, DC to
25OMHz, VSWR of cl.1

Female BNC connector to double banana plug

3-2

SECTION 3

Service Information

3.3.5

Before calibration, the top and bottom covers must be re­moved as covered below (see Figure 3-l).

Cover Removal

WARNING
Potentially hazardous voltages may be pre­sent inside the instrument. Use caution
when performing calibration.

CAUTION
A conductive coating is applied to the inner
surface of the covers. Be carefulnot to scratch
the coating when removing the covers. Also
be careful not the peel off the corners of the

polyester film covering the front panel; the

film can be peeled off relatively easily.

1. Place the instrument upside down on a soft cloth or
rubber mat to avoid scratching the top cover.

2.

Remove the four corner screws that secure the bot­tom cover, then remove the cover.

3. Place the instrument right side up.

4.

Remove the top cover by separating it from the chas-

3.3.6

Calibration adjustments are shown in Figure 3-2.

Callbratlon Adjustments

~ Fimm 3-I.

1. Remove Screws

Cover Removal

2. Remove Bottom Cover

3. Remove Top Cover

33

SECTION 3

Service

Information

Front Panel Side

,+24V (TP501)

Figure

3-2.

Analog Board

Rear Panel Side

(NP-210221 Calibration

‘-24V (TP503)
\-15V (TP505)

GND (TP502)

Adiustments

3-4

SECTION 3

Service Informafion

3.3.7

Function Synthesizer Connections

For all adjustment procedures, a Model 3930A Multifun­ction Synthesizer must be connected to the DIGITAL IN
connector of the Model 3933A, as shown in Figure 3-3.
Use the CA-94 digital cable supplied with the Model
393314 to make the connections.

CA-94 Digital Cable

mm

Model 3930A Synthesizer Model 3933A Being Tested

Figure 3-3.

3.3.8

Calibration should be performed in the se­quence presented.

Function Synthesizer Connections

Calibration Procedures

NOTE

DC Offset

1. Connect the Model 197A DMM to the Model 3933A

FCTN OUT jack, as shown in Figure 34. Also make
sure the Model 3930A is connected properly as indi­cated.

2. Set the Model 197A to the DCV function, and enable
auto-ranging.

3. Setup the Models 3930A and 3933A as follows:

Model 3933A: Factory Default (press SHIFT PRST)

RANGE: FXD (press SHIFI 0)
FCTN: DC

Model 3930A: Factory Default (press SHIRT PRST)

go~j<cE: Eic’l; “&
MODE: GATE

4. Adjust R213 (DC OFS) so that the DMM reads OV f

1mV.

5. Program a Model 3933A DC offset value of -15V (use

OFFSET>.

6. Adjust R211 (DC SPAN) for a DMM reading of -15V

* 0.002v.

7. Program a Model 3933A DC offset voltage of +15V.

8. Verify that the DMM reading is between 14.996V

and 15.002V. If not, repeat the DC span adjustment
(step 6) to minimize the errors in the -15V and +15V
readings.

9. Program a DC offset voltage of OV, and verify that

the DMM reading is still OV f 1mV. If not, re-adjust
R213 (DC OFS) for a reading within these limits.

10. Setup the Model 3933A as follows:
FCTN: SIN
OFFSET: OV

AMPTD: 3OVp-p

11. Adjust RlOl (OFS) for a DMM reading of OV f 1mV.

Figure 3-4.

Model 3930A

Synthesizer

Connections to

CA-94 Digital Cable

Model 197A DMM

Model 3933A
Being Tested

Pomona 1466

BNC-Banana

\

Function Output

SECTION 3

Service Information

SIN Level

1. Connect the Model 197A DMM to the FCTN OUT
jack of the Model 3933A (Figure 34). Also make sure
the Model 3930A is connected properly as indicated.

2. Set the Model 197A to the DCV function, and select
auto-range.

3. Setup the Models 3930A and 3933A as follows:
Model 3933A: Factory Default (press SHIFT PRSTI

PHASE: -90”
AMrID 7*49vp-p

Model 393OA: Factory Default (press SHIFT PRST)

SOURCE: EXTI
MODE: GATE

4. Adjust R109 (AMP) for a DMM reading of -3.745V f

0.004v.

AM Balance

1. Connect a Model 197A DMM to FCTN OUT, and

connect a second Model 3930A to the AM IN jack of
the Model 3933A being calibrated (see Figure 3-5).
The second Model 3930A will be used to provide an
amplitude modulation signal.

NOTE
Connect an oscilloscope, if one is available, in
parallel with the Model 197A input terminals
in order to make adjustments easier.

2. Set the DMM to the ACV function, and select auto-

3. i%$%e Model 3930A used for the AM signal as fol­lows:

Factory Default (press SHIFT l?RST>

AMPTD: 2Vp-p

4. Setup the first Model 3930A and the Model 3933A

being calibrated as follows:
Model 3933Az Factory Default (press SHIFT PRST)

AMrm: 7.49vp-p
AMEON

Model 3930A

Synthesizer

Model 3930A

Synthesizer (Used

for AM Signal)

I

/

CA-94 Digital Cable

Dis

lital

01

JT

I

Model 7051-2

Coaxial Cable

\

Function Output

AM

Being Calibrated

Digital

IN IN \ I

Model 3933A

Model

197A

Model 7051-2 Coaxial Cable

\

Function OutplI+

DMM

Pomona 1466

BNG

ana

Figure 3-5.

3-6

Second Model 3930A Connections

SEClTON 3

Service Information

Model 3930A: Factory Default (press SHIFT PRST)

SOURCE: EXT 1

MODE: GATE

5. Adjust R207 (AM BAL) so that the multimeter indi­cates 1OmV or less. (If an oscilloscope is being used,
adjust for minimum signal amplitude.)

6. Select the DCV function on the DMM.

7. Adjust R208 (AM OFS) for a DMM reading of OV f
20mV.

8. Repeat steps 2 through 7 three or four times until
both the AM balance and AM offset reading limits
stated in steps 5 and 7 are satisfied.

AM Gain

1. Disconnect the second Model3930A from the AM IN
connector, and make sure the DMM is still connected
to the FCTN OUT jack of the Model 3933A being cali­brated (Figure 3-4).

2. Select the DCV function and auto-ranging on the
DMM.

3. Setup the Model 3933A as follows:

PHASE: -90’

4. Adjust R203 (AM GAIN) for a DMM reading of

-1.872V f 0.009V.

AM Offset

1. Connect the Model 197A DMM to FCTN OUT
(Figure 3-4).

2. Select the DCV function and auto-ranging on the
DMM.

3. Setup the Model 3933A as follows:
PHASE: 0”

4. Adjust R208 (AM OFS) for a DMM reading of OV f
1OmV.

Square Wave DC Level

1. Connect the Model 197A DMM to FCTN OUT
(Figure 3-4).

2. Select the DCV function and auto-ranging on the
DMM.

3. Setup the Model 3933A as follows:
FacctoNv$efault (press SHIFT PRST)

AMr&: 7.49vp-p
PHASE: +90”

4. Setup the Model 3933A as follows:

PHASE: -90”

5. Adjust R316 (SQ-) for a DMM reading of -3.7445V f

0.0055v.

Square Wave Duty Cycle

1. Connect the PM 6645C counter A input to the FCTN
OUT jack, as shown in Figure 3-6.

2. Set the PM 6654C counter to the pulse width meas­urement mode.

3. Setup the Model 3933A as follows:
Factory Default (press SHIFT PRST)

FREQ: 1OOHz
AMPTD: 2ovp-p
FCTN: j-L

4. Adjust R308 (DUTY) for a counter reading of 5msec f

0.005msec.

1 Fimre 3-6.

CA-94 Digital Cable

Model 3930A

Synthesizer

Model 3933A

Being Calibrated

Connections to PM6654C Counter

\

Function Output

input A for
impedance

3-7

SECTION3

Service Information

Frequency Response

1. Connect the Model 8920A RMS Voltmeter to the
FCTN OUT jack, as shown in Figure 3-7. Be sure to
use the 5OSJ feed-through terminator as indicated.

2. Make sure the voltmeter dB and REL modes are dis­abled.

3. Setup the Models 393014 and 3933A as follows:
Model 3933A: Factory Default (press SHIFT PRST)

AMrIm 3.74vp-p

Model 393OA FREQ: lkbfz

4. Allow the voltmeter reading to settle, then enable dB

- and REL in that order.

5.

Setup the Model 3930A as follows:

FREQ:800kHz

6. Adjust C108’ for an RMS voltmeter reading of
+O.b4dB f 0.03dB.

CA-94 Digital Cable

Display Contrast

7. Press the front panel DSPL key to return the display
to normal.

8. Adjust R752 (CONTRAST) for the desired display
contrast. (R752 is located on the control board
(NE-10409) near the front panel.)

3.3.9

Cover Replacement

After calibration, replace the top and bottom covers, and
secure them with the four screws removed earlier. Be
careful not to scratch the conductive coating applied to
the inside of the covers, and be sure not to peel off the
front panel polyester film.

Model 7755

Model 3930A

Synthesizer

Fiwre 3-7. Connections fo Wideband AC DVM

Model 3933A

Being Calibrated

- Model 7051-2 Coaxial

\

Function Output

Cable

3-8

SECTION 3

Service Information

3.4 FAN FILTER CLEANING

The fan filter should be cleaned at least once every three’
months when the unit is operated in a clean environment
or at least once a month when the unit is operated in a
dirty environment. The fan filter element should be
cleaned as follows:

1.

Turn off the instrument power and disconnect the
line cord.

2.

Remove the filter cover on the rear panel.

3.

Remove the filter element.

,4.

Soak the filter element in a solution of mild detergent
and water until clean.

5.

Rinse the filter element thoroughly in clean water,
then allow the filter to dry thoroughly before re­placement.

6.

When the filter has dried completely, install the filter
and cover.

CAUTION
The instrument should not be operated
without the filter in place.

3.5 FCTN OUT JUMPER

The FCTN OUT jumper, which is located on the control
board, allows you to select whether or not the output sig­nal is turned on when power is first applied to the instru­ment. (As shipped, FCTN OUT is enabled when power is
turned on). Use the procedure below to set the jumper

position.

However, if you notice the instrument no longer stores
setups even after charging the battery, the battery is
probably defective and should be replaced. Follow the
steps below to replace the battery.

CAUTION
Many parts on the internal circuit boards are
static sensitive. To avoid possible damage,
perform any repair operations only at aprop­erly grounded workstation, and use only
grounded-tip soldering irons and anti-static
de-soldering tools.

1.

Disconnect the line cord and all other instruments
from the Model 3933A.

2.

Remove the top and bottom covers (refer to para­graph 3.3.5 for procedure).

3.

Note the positions of the various cables connected to
the control board, then disconnect all cables from the
board.

4.

Remove the screws, and release the fasteners that se­cure the control board to the chassis.

5.

Slide the control board towards the front panel until
the jacks clear the rear panel.
Remove the control board.

6.

7.

Unsolder the battery leads, and cut the sealant that
secures the battery. Remove the battery.

8.

Install a new battery, taking care to observe polarity.

9.

After soldering, secure the battery to the board using
an electronics-approved silicone or RTV sealer.

10.

Install the control board, and connect all cables to the
board.

11.

Replace the covers.

12.

Turn on the power for 50 hours to fuhy charge the
new battery.

1.

Disconnect the line cord and all other instruments
from the Model 3933A.

2.

Remove the top and bottom covers (see paragraph

3.3.5 for details).

3.

Set J401 (FCTN OUT) to the desired position. (J401 is
located on the control board, Np10409, near the rear
panel.) Set the jumper to FCTN OUT ON to enable
FCTN OUT at power on, or set it to FCTN OUT OFF
to leave FCTN OUT disabled at power on.

4.

Replace the top and bottom covers.

3.6 RECHARGEABLE BATTERY
REPLACEMENT

The rechargeable battery (BT151), which backs up setup
RAM, does not normally require field replacement.

3.7 REPAIR

Instrument repair may be necessary in cases where the
unit cannot be properly calibrated.

3.7.1 Factory Service

If the Model 3933A is still under warranty, it is recom­mended that the unit be returned to the factory or Keith­ley authorized repair facility for repair or calibration.
When returning the unit for service, include the follow­ing:

l

Complete the service form at the back of this manual.

l

Advise as to the warranty status of the instrument.

3-9

SECTION 3

Service Information

l

Write the following on the shipping label: ATTEN­TION REPAIR DEPARTMENT.

Table 3-4. Board Level Repair Summary

3.7.2

Power Supply Test Points

Table 3-3 summarizes power supply test points, and
Figure 3-8 shows the test point locations. Note that f15V
and &24 supply voltages are reference to TP502, and the
+5V supply is referenced to TP507.

Table 3-3. Power Supply Test Point Summary

Test Point

TF501
TP502
TP503 t

TP504
TP505
TP506
TP507

Description
+24V supply

GND (f15V, ti4V supplies)

-24V supply
+15v supply

-15v supply
+5v supply
GND (+5V supply)

Problem

1. DC OFFSET VAR

2. OUTPUTATT

3. FCTN OUT ON/OFF

4. PHASE VAR

5. WAVEFORM

6. AMPLITUDEVAR

7. AM

8. DUTY CYCLE VAR

9. DUTY CYCLE STABILITY

10. PHASE SWEEP

11. sYNcoTJT

1 Probable Cause

B
B
B

A

A or B

B
B

A or B

B

A

B

12. SWEEP MKR OUT

13. SWEEP SYNC OUT

14. X DRIVE OUT 1

A: Control circuit board (NP-10409)
8: Analog circuit board UVP-21022)

2

A

3.8 REPLACEABLE PARTS

3.8.1

Table 3-5 summarizes available Model 3933A replace­ment parts. Figure 3-9 shows the location of mechanical
piiXtS.

Parts List

3.7.3

Board-level Repair

Table 3-4 summarizes which circuit board is most likely
at fault for various problems. Paragraph 3.8 below lists
replacement boards and certain other parts. If board re­placement fails to fix the problem, the most likely cause of
the fault is the wiring between the boards.

3.8.2

Ordering Parts

To order a part, or to obtain information on replacement
parts, contact your Keithley representative or the factory.
When ordering parts, include the following information:

l

Instrument model number

l

Instrument serial number

l

Keithley part number

l

Part description

3-10

Front Panel Side

SECTION 3

Service Information

R308

DUTY

Cl08 AMP

R109

R101

OFS

R208

AM OFS

R207

AM BAL

Figure 3-8.

AM GAIN DC SPAN

Power Supply Tesf Point Locations

DC OFS

Rear Panel Side

3-11

SECTION 3

Service

Information

Figure 3-9.

3-12

Model 3933A Exploded View

Table 3-5. Replaceable Parts

Description

Part
Number

SECTlON 3

Service Information

Qty.

Control board (NP-10409)
Analog board @II?-21022)
Fan
Air filter
Flat head screw

080-33641-00
080-33650-00
300-00718-00
459-00205-00
600-01241-00

(for air filter)

Fuse holder

Noise filter

302-04054-00
240-03328-00

(AC receptacle)
BNC connector
Power switch (internal)
Power switch

310-00347-00

332-l 9141

cc- -_ --- --

-t-l0

332-19133-00

(on front panel)
Flexible wire

332-19150-00

(for power switch)
Voltage selecting switch
Rotary encoder
Ground terminal
LCD
EL back light (for LCD)
Power transformer
Rear panel
Hex. stud
Grommet
SW spacer (for power switch)
Collar (for LCD)
BNC bush
BNC spacer
Spacer (for rotary encoder)
Hex. spacer

332-50057-00
332-90041-00
330-05389-00
304-10118-00
100-70028-00
244-10890-00

400-11704-00

606-00187-00
546-00146-00

520-05356-00

606-02236-08

446-00046-00

540-00157-00

520-05976-00

606-01892-00

(for power switch)
Knob (for rotary encoder)
Button (for power switch)
Hex. stud (for NE-10409)
Standoff (for NJ?-10409)

486-24060-00
359-03554-00
606-00101-00

529-00185-00
Battery
Fuse (lOOV/12OV)
Fuse (22OV/24OV)

*Part number not available at time of printing; contact repair
department.

k-96-2

FU-96-1

1
1
1
1
4

1
1

3
1
1

1
1

1
1

:
1
1
4
3

1
4
4
4

1
2

1
:.

4

:

1

3-13

APPENDIX A

Typical Data

INTRODUCTION

Appendix A provides the typical performance data for
the Model 3933A.

This instrument was thoroughly tested and inspected

and certified as meeting its published specifications
when it was shipped from the factory. However, the typi-

cal data represents mean values of measurements for
each Model 3933A. Thus, measured performance of your

Model 3933A may be different than that indicated by the

typical data curves shown here.

A-l

APPENDIX A

Typical Data

Amplitude

W4

+0.2

0

-0.2

-0.4

Figure A-l.

Total Harmonic
Distortion
Ratio (%)

W)

0.2

0.1

Ik

Note: Voltage is set voltage, load 50 ohms,

1 kHz base

10k

Frequency (Hz)

Sine Wave Amplitude - Frequency Characterisfics

1 OOk IM

Fiaure A-2.

A-2

Ik

Frequency (Hz)

Note: Amplitude setting 3OVp-p, load 50 ohms

Total Harmonic Distortion - Freuuencu Characteristics

10k

1OOk

Phase (degrees)

4
2

APPENDIXA

Typical Data

Fimre A-3.

0 ------.---*---=‘---

-2

-4

Ik

Note: Phase re 193OA when it’s two-phase

1930A’s start/stop phase: 0 degrees
1933A’s phase: 0 degrees
Both 1930A and 1933A have amplitude 30 Vp-p, waveform
sine, load 50 ohms.

Phase - Freauencv Characterisfics

10k

Frequency (Hz)

100k

­\

\

\

I,

\

1M

A-3

Model 3933A Specifications

B.1 ELECTRICAL SPECIFICATIONS

Waveforms
Types

Oscillation Modes

Set by 3930A mode.

Frequency

Set by 3930A frequency.
Waveform and Frequency Range

Phase

Setting Range
Display
Accuracy (when 3930A is in
CONT mode)

pconly, ‘L, I-L t \ t/l ,u

2, , n (Dutycyclefixed at50%)
2, ,/l ,U , n (Duty cycle varies

-360” to 360” (value corresponding to 0” at 3930A’s start/stop phase)
Maximum 4 digits f resolution 0.1” (fixed)
’ Set both 3930A and 3933A to these settings:

DC offset OV, AM off, 50R load, same waveform, 18”-28°C.
o Waveform duty cycle is fixed or variable on both devices. (cycle is optional)
o Amplitude setting is from 3O.OmVp-p to 3O.OVpp (when output range is FXD, above 3OOVp-p),

and can be set independently.
’ When connecting in sequence, phase number n is per this diagram:

APPENDIX B

1 0.1mH2 to 1.2MHz

O.lmHz to 1OOkHz

I393OA+---+ 3933Al

n=l

However, n < 6 (to max of 6 phases)
o Accuracy corresponds to:

(3933A phase setting) - (393OA’s start/stop phase setting)

D = + 0, -(n-2) x 40ns
2/

n

(while rising)

\
/l (while falling)

\ (while rising)

Specifications subject to change without notice.

13933141

n=2 n=3

When duty cycle is 50% (FXD)
When duty cycle is variable

. . . . . .

fiO.1” + 12011s) + D
1U0.5~ + 120ns) + D

f(0.1’ + 220ns) + D
f(O.1” + 9On.s) + D
f(O.l” + 24Ons) + D

ELECTRICAL SPECYFICATIONS (CONT.)

Output Characteristics (Waveform Output)

r

Maximum Output

Display (Open Circuit Value)

AC Oscillation Setting Range
(at DC offset OV)

AC Amplitude Accuracy

(when 3930A is in CONT mode)

DC Voltage Setting Range and
Accuracy (when DC only)
AC and DC Setting Range and
DC Voltage Accuracy when
AC+DC
Amplitude and Frequency
Characteristics (when 3930A

is in CONT. mode)

‘L

Spectrum J?urity
(when 3930A is in CONT mode)

Per Table B-3 AC + DC Minimum AC Amplitude, Resolution and Accuracy. The sum of
AC amplitude’s absolute peak and DC voltage’s absolute value is less than 15V.

1kHz reference frerquency, DC offset OV, AM off, 5Of2 load, amplitude setting BO.OmVp-p to
3O.OVp-p (when output range is FXD, more than 3.OOVp-p), \

otherwise measure p-p value.
L

L
n (duty cycle upto1OOkHz ti%
fried/50%
variable)
/1
DC offset OV, AM off, 5OR load, amplitude setting from 3O.OmVp-p to 3O.OVp-p (when output
range is FXD, more than J.OOVp-p)
Total harmonic distortion lOH!z to 1ookHz
Harmonic (when amplitude setting lOOkH2 to 5ookHz
is dO.OVp-p)
Spurious (when amplitude setting up to 5OOkHz -55dBc max
is JO.OVp-p 5ookI-J.z to 1.m

up to 1ookHz M.ldB
1OOkHz to 7OOkHz z!zO.3dB
7OOkHz to 1MHz +0.3dB, -0.5dB
MHz to 1.2MHz +OJdB, -l.OdB
up to lOkH2

33%

I

5ookHz to 1.2MHz

is effective value measurement;

0.1% max

-4OdBc max

-3OdBc max

4OdBc max

ELECTRICAL SPECIFICATIONS (CONT.)

Io.utPut

Output Voltage
Signal Ground Common with waveform output
Connector BNC. front Dane1

AM Input

Gain

Input Voltage Range
Modulation Range
Modulation Signal Band
Carrier Signal
Input Impedance
Signal Ground
Connector

‘ITL Level (51f2 in series with 74ACOO output)

At klV, 100% modulation. At OV, output is half of displayed value.
At -lV DC, carrier is SuDDressed.

-3v to +lV
2100%
DC to 1ookHz
up to lOOkI (Q )
lOkf2
Common with waveform output
BNC, front panel

LA

ELECTRICAL SPECIFICATIONS (CONT.)

Input

output

X Drive Output

Other Function

Replace marker

phase

Digital I/O for Multi-Phasing

Digital In

Digital Gut

connector

B&, rear panel 1

I

Output voltage OV to +lOV &S%)/open
Signal
characteristics

OV to +lOV (phase increasing1

+lOV to OV (phase decreasing)
Output Impedance 6OOQ unbalanced
Load impedance
Connector

low1 minimum

BNC, rear panel

with center phase

Input Voltage
Connector
Connection

TTL level

36-pin, rear panel

Connect 393OA’s or 3933A’s digital out with this device’s DIGITAL IN via

special cable.
Output Voltage

connector

TTL level

Xi-pin,

rear panel

a

ELECTRICAL SPECIFICATIONS (CONT.)

Memory

Memory Contents

Main

Phase*, amplitude*, DC offset*, waveform

Sweep-Related

Start*, stop*, center*, span*, marker*, sweep time*, sweep function

Other

Square wave duty cycle*, AN on/off, beep sound (on/off), output range mode ALlTO/FXD

Modify

Note: Parameters listed with *show cursor position and step size.
10 units
30 days or more after full charge (stored at room temperature)

1 Setting Protection When Power is Off

Function 1 Parameters in effect prior to power-off are stored and become effective at next power-on

(except for waveform output on/off).

Contents Protected

Battery Backup

Same items as in Memory Contents, plus lock (on/off), GPIB address, delimiter.
Identical to Memory

Modify

Format
Up/Down Step Size

Parameters that can’t be modified

Per cursor movement and MODIFY knob.
fl Increases or decreases cursor position value by 1.
i5
x+2
x+10 Multiples or divides entire value by 10.
Note: The above step sires apply only to the parameters listed with * in Memory Contents. Others
change step size by fl only, and cursor position is fixed.
Memory number, GPIB address, and delimiter

Increases or decreases cursor position value by 5.
Multiplies or divides entire value by 2.

1

Display Function

Synchronously displays waveform output on/off, frequency, amplitude, DC offset, waveform, oscillation mode, AM on/off,
and sweep state.

Disables most front panel key entries and operating condition changes. Current parameter values can be displayed. GPIB input and certain
BNC inputs are enabled.

ELECTRICAL SPECIFICATIONS (CONT.)

Preset

Sets the parameters listed below.

The modification step size is fl. The underline indicates the cursor position.

Main

. Phase

Amplitude
DC offset
Waveform

Sweep-Related

Start phase
Stop phase
Center phase
Span phase
Marker phase
Sweep time
Sweep function

Others

AM

n Duty cycle
Beep sound

Output range mode

Q.0 deg
Q.OOmVp-p (Q.OOVp-p)
Q.OOmV @.OOv)

%

-18Q.O deg

180.0 deg

Q.0 deg

368.0 deg
Q.0 deg

1.000s
n

off
fixed 58.0%
on
AUTO

Display

Main parameter display status

B.2 GPIB INTERFACE

Local Key
Connector

DAV, EOI
Switch for return-to-local function
IEEE-438 24pin GPIB connector, rear panel

T&state

B.3 GENERAL

Signal Ground

Power Source

Range of Ambient Temperature
and Humidity
External Size
Weigth

Table B-l. AC Amplitude Setting Range for OV DC Offset

output

Range
Mode

AUTO

FXD

AC

(P-P)

3o.ov to 3.oov 10.6V to 1.06V

2.99V to 300mV 1.05V to 106mV

299mV to 3O.OmV

29.9mV to 0.3OmV 105mV to O.llmV
3o.oov to o.oov

output

Range

Mode

AC

(P-P)

The grounding pins of all input/output connectors are connected to chassis except for waveform
output, synchronous output, and AM input.
Voltage 100,120,220 or 240V AC flO% (25OV max.)
Frequency 48to62Hz
Power Consumption

Approx. 38VA
Operating O”-400C, lo-901 RH (without condensation)
Storage

-loo-50°C, lo-SO% RH (without condensation)
Excluding Projections 216 0 x 132.5 (HI x 350 (D) mm, 8.5 0 x5-1/4 (HI x 133/4 (D) in.
Approx. 4.6kg (10 lbs.)

‘L

Hardware

output

Resolution Attenuator

105mV to 10.6mV

cvp-p only)

%/lnu

IIllS

dBV

20.5 to 0.5

0.4 to 19.5

-19.htn-39.5

- _ - -- - _ -

49.6 in-m.3

-_.- _- . _.-

cvp-p only)

dBV

(P-P)

15mV l/l

1.5mV

15nuv

---r-

I

I

l.%rV

I

--r-

15mV

Hardware output

Resolution

(P-P)

(See note)

l/10

l/100

l/1000

l/l

Attenuator

(See note)

AUTO

/

output

Range

Mode

AUTO

FXD

3o.ov to 3.oov 8.66V to 866V 18.8 to 1.2

299V to 300mV

299mV to 3O.OmV 86.5mV to 8.66mV

29.9mV to 0.3OmV
3o.oov to o.oov

AC

(P-P)

3o.ov to 3.ooV

2.99V to 300mV

299mV to 3O.OmV

299mV to 0.3OmV

3o.oov to o.oov

865V to 86.6mV -1.3 to -21.2 -1 l/10

-21.3 to -41.2 15oJlv l/100

8.65mV to 0.09mV
(VP-p only)

-41.3 to -80.9
(VP-p only)

I-L

IUIS

15.ov to 1.5ov

1.49V to 150mV

149mV to 15.OmV

14.9mV to 0.15mV
(VP-P omY)

23.5 to 3.5

3.4 to -16.5

-16.6 to -36.5

_-.- _- -_._

sfxtn-76.5 15uv

- -. - -- - .-

(VP-p only)

Note: When switching the output attenuator, the instantaneous waveform goes off.

dBV

15mV l/l

15pv l/1000

15mV

Hardware output

Resolution Attenuator

(P-P)

15mV l/l

1.5mV l/10
15ouv

I

I

--I-.

8

I

I

15mV

l/l

(See note)

1 /loo

1 /lOOO

l/l

1

Table B-2. DC Only Voltage Setting Range, Resolution, and Accuracy

(open load, 18°-280C)

Note: When switching the output attenuator, the instantaneous waveform ouptut goes off.

Table B-3. AC + DC Minimum AC Amplitude, Resolution, and Accuracy (open load)

htput

rc

I

iange

1

m

i

W-TO

FXD

NOtes:

1. When switching the output attenuator, the wavef?rm output goes off for a moment.
2 Cumulative voltage = AC amplitude setting

3.

Cumulative
Voltage
(SeeNote p-p rms
More than

1.5v 1.5v

More than

150mV 150mV

More than

More than

15mV 15mV

Less than 0.3OmV 0.3OmV O.llmV -79.2 0.09mV -80.9 0.15mV -76.5 15cIvpp 7.3pV O.llmV -79.2 0.09mV

Less than
15mV 15mV
Not related

Not related
to cumulative1

DC voltage a-acy is when

236mV 1OlmV -19.9 82.5mV -21.6 143mV -16.9 15mVp-p 7.3mV

28.6mV lO.lmV -39.9 8.25mV -41.6 14.3mV -36.9 l.SmVp-p 73OnV More than

28.6mV lO.lmV -39.9 8.25mV

I I II II II I

2.86mV 2.86mV l.OlmV -59.9 0.83mV -61.6 1.43mV -56.9 15OuVp-p 73pV l.OlmV -59.9 0.83mV

1 1

O.OOV

o.oov

frequency

Minimum AC Amplitude 1 Hard. 1 Hard.

%

I

(p-p)

divided by 2 plus DC voltage setting (W.

is abaa Ik&,r\l , Ahi off, open load+ 18Wsoc

%A\ I-L

dBV rms

(VP-p only)

dBV rms dBV

-41.6 14.3mV -36.9 l.SmVp-p 73OnV

-61.6 1.43mV -56.9 15OuVp-p 73pV

-80.9 0.15mV -76.5 15cIvpp 7.3pV

ACA DCV
Resl. Resl.

1

15mVp-p 7.3mV 15mVp-p I7.3mV

I I

/

output

Atten.
DC Voltage Accuracy
f(0.246 of AC amplitude
setting (p-p) +O.l% of DC
voltage setting +8mV)

f(O.296 of AC amplitude
setting (p-p) +0.6% of DC
voltage setting +0.8mV)

f(0.246 of AC amplitude
setting (p-p) +l% of DC
voltage setting +8OcIv)

(Not specified) l/1000

f(0.296 of AC amplitude
setting (p-p) +O.l% of DC
voltage setting +8mVI

(See Note 1

l/l

l/10

l/100

l/l

I

I

I

I

I

f

t

-

L-d

--a

I

I

Figure B-Z. Outer Dimensions of the Model 393314

Index

A

AM Balance, 3-6
AM Gain, 3-7
AM Offset, 3-7
Amplitude Accuracy, l-4
Amplitude Modulation, 2-3
Amplitude Oscillator Operation, 2-3
Analog Circuit Description, 2-3
Analog Section, 2-1
Analog Section Block Diagram, 2-3

B

Block Diagram, 2-l
Board-level Repair, 3-10

C

Calibration, 3-l
Calibration Adjustments, 33
Calibration Procedures, 3-5
Control Section, 2-l
Cover Removal, 3-3
Cover Replacement, 3-8

D

D/A Converter, 2-3

DC Level (Square) and DC (Offset) Error

(Sine), l-10
DC Voltage Accuracy, l-10
Display and Keyboard Section, 2-l
Display Contrast, 3-8

E

Environmental Conditions, l-l, 3-2

Factory Service, 3-9
Fan Filter Cleaning, 3-9
FCTN Out Jumper, 3-9
Frequency and Duty Cycle Accuracy, l-3
Frequency Response, 3-8
Frequency Response (Sine), l-6
Frequency Response (Triangle, Sawtooth,

Square), 1-8

Function Synthesizer Connections, 3-5

I

Initial Conditions, l-1,3-2

L

Line Fuse Replacement, 3-1

Line Power, l-l, 3-2

M

Multiphase Oscillator Operation, 2-3

0

Ordering Parts, 3-10

P

Parts List, 3-10
Performance Verification, l-l
Phase Shift Section, 2-l

Power Supply Section, 2-3
Power Supply Test Points, 3-10
Principles of Operation, 2-l

R

Rechargeable Battery Replacement, 3-9
Recommended Calibration Equipment, 3-2
Recommended Test Equipment, 1-l
Repair, 3-9
Replaceable Parts, 3-10
Rise and Fall Ties, I-10

S

Service Information, 3-1
SIN Level 3-6
Square Wave DC Level, 3-7
Square Wave Duty Cycle, 3-7

Square Wave Generator, 2-3
Synthesizer Connections, l-2

T

Total Harmonic Distortion, l-9

V

Verification Procedures, l-2

M INSTRUMENTS

SERVICE FORM

I

Model No.

Serial No.
Name and Telephone No.
Company

List all control settings, describe problem and check boxes that apply to problem.

OIntermittent
Cl IEEE failure

q

Front panel operational

Display or output (circle one)

q

Drifts

aunstable

q

Overload

q

Calibration only

OData required

(attach any additional sheets as necessary.)

aAnalog output follows display q Particular range or function bad; specify

q

Obvious problem on power-up aBatteries and fuses are OK

q

c]All ranges or functions are bad

C]Unable to zero

•1 Will not read applied input

q

Certificate of Calibration required

Checked all cables

Date

Show a block diagram of your measurement system including all instruments connected (whether power is turned on or not).
Also, describe signal source.

Where is the measurement being performed?

What power line voltage is used?
Relative humidity?

Any additional information.

(If special modifications have been made by the user, please describe.)

(factory, controlled laboratory, out-of-doors, etc.)

Ambient Temperature?

Other?

Be sure to include your name and phone number on this service form.

l

Instruments Division, Keithley Instruments, Inc.

WESTGERMANY: Keithley Instruments GmbH l Heiglhofstr. 5 l Munchen 70 l 089-71002-O l Telex: 52-12160 l Fax: [phone]
GREAT BRITAIN: Keithky Instruments, Ltd. l The Minster l 58, Portman Road l Reading, Berkshire RG 3 IFA l 01144 734 575 666 l Fax [phone]
FRANCEZ
NETHERLANDS: Keithky Instruments BV l Avelingen West 49 l 4202 MS Gorinchem l P.O. Box 559 l 4200 AN Gorinchem l 01830-3%X33 l Telex: 24 684 l Fax: [phone]
SWITZERLAM):
AUSTRIA:
ITALY: Keithley Instruments SRL l Vi&S. Gimignano 4/A l 20146 MiIano l 02-4120360 or 02-4156540 l Fax [phone]

Keitbky Instruments SARL l 3 Alk des Ganys l B.P. 60 l 91124 Palaiseau/Z.L l l-6-0115 155 l TeIex: 600 933 l Fax l-6-0117726

Keithley Instruments SA . Kriesbachstr. 4 l 8600 Dubendorf l 01-821-9444 l T&x: 828 472 l Fax: [phone]
Keitbley Instruments GesmbH . Rosenbugelstmsse I2 l A-1120 Vienna l (0222) 84 65 48 l Telex: 131677 l Fax: [phone]

28775 Aurora Road l Cleveland, Ohio 44139 l [phone] l Fax: [phone]