Tektronix 3330 Service Manual

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 normaI wear or failure to follow instructions.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTI ES, 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,

INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRU-

MENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE OF THE POS-

SIBILITY 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. l 28775 Aurora

CHINA:
FRANCE: Keithley Instruments SARL l BP 60 l 3 All&e des Garays l 91122 Palaiseau (adex * 33-I-60-11-51-55 * Fax: 33-1-60-I l-77-26
GESMANY Keithley Instruments GmbH * Landsberger Strasse 65 l D-821 10 Germering, Munich l 49-89-8493070 l Fax [phone]
GREAT BRITAIN: Keithley Instruments, Ltd. l The Minster l 58 Porunan Road l Reading, Berkshire, England RG3 lE.4 l 44-l 189-596469 l Fax: [phone]
ITALY: Keithley Instruments SRL l Viale S. Gimignano 38 l 20146 Milano * 39-2-48303008 l Fax: 39-z-48302274
NETHERLANDS: Keithley Instruments BV * Avelingen West 49 * 4202 MS Gorinchem * 31-(0)183-635333 l Fax [phone]
SWITZERLAND:
TAIWAN: Keithley Instruments Taiwan l IFI.., 85 PO Ai Street l Hsinchu, Taiwan l 886-3-572-9077 * Fax: [phone]

Keithley Instruments China. Yoan Chen Xin Building, Room 705 * 12Ymnin Road, Dewai, Madian * Beijing 100029~8610-62022886 l Fax: [phone]

Keithley Instruments SA. Kriesbachsuasse 4 l 8600 Diibendorf l 41-I-8219444 *Fax: 41-l-8203081

Road l Cleveland, OH 44139 l 440-248-0400 l Fax: [phone] l http://www.keithley.com

Model 3330 LCZ Meter

Service Manual

01993, Keithley Instruments, Inc.

Test Instrumentation Group

All rights reserved.

Cleveland, Ohio, U.S.A.

First Printing February 1993

Document Number: 3330-902-07 Rev. A

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

Safety Precautions

The following safety precautions should be observed before using
this product and any associated instrumentation. Although some in­struments and accessories would normally be used with non-haz­ardous voltages, there are situations where hazardous conditions

may be present.

This product is intended for use by qualified personnel who recog-

nize shock hazards and are familiar with the safety precautions re­quired to avoid possible injury. Read the operating information
carefully before using the product.

The types of product users are:

Responsible body

and maintenance of equipment, for ensuring that the equipment is
operated within its specifications and operating limits, and for en-

suring that operators are adequately trained.

Operators

trained in electrical safety procedures and proper use of the instm­ment. They must be protected from electric shock and contact with
hazardous live circuits.

Maintenance personnel

to keep it operating, for example, setting the line voltage or replac­ing consumable materials. Maintenance procedures are described in
the manual. The procedures explicitly state if the operator may per-

form them. Otherwise, they should be performed only by service
personnel.

Service personnel

safe installations and repairs of products. Only properly trained ser­vice personnel may perform installation and service procedures.

is the individual or group responsible for the use

use the product for its intended function. They must be

perform routine procedures on the product

are trained to work on live circuits, and perform

Users of this product must be protected from electric shock at all
times. The responsible body must ensure that users are prevented
access and/or insulated from every connection point. In some cases,
connections must be exposed to potential human contact. Product
users in these circumstances must be trained to protect themselves
from the risk of electric shock. If the circuit is capable of operating
at or above 1000 volts,

exposed.

As described in the International Electrotechnical Commission

(IEC) Standard IEC 664, digital multimeter measuring circuits
(e.g., Keithley Models 175A, 199,2000,2001,2002, and 2010) are
Installation Category II. All other instruments’ signal terminals are
Installation Category I and must not be connected to mains.

Do not connect switching cards directly to unlimited power circuits.
They are intended to be used with impedance limited sources.
NEVER connect switching cards directly to AC mains. When con­necting sources to switching cards, install protective devices to lim-

it fault current and voltage to the card.
Before operating an instrument, make sure the line cord is connect-

ed to a properly grounded power receptacle. Inspect the connecting
cables, test leads, and jumpers for possible wear, cracks, or breaks
before each use.

For maximum safety, do not touch the product, test cables, or any
other instruments while power is applied to the circuit under test.
ALWAYS remove power from the entire test system and discharge

any capacitors before: connecting or disconnecting cables or jump­ers, installing or removing switching cards, or making internal
changes, such as installing or removing jumpers.

no conductive part of the circuit may be

Exercise extreme caution when a shock hazard is present. Lethal

voltage may be present on cable connectorjacks or test fixtures. The
American National Standards Institute (ANSI) states that a shock
hazard exists when voltage levels greater than 30V RMS, 42.4V
peak,or60VDC~epresent.Agoodsafetypracticeistoexpect

that hazardous voltage is present in any unknown cir­cuit before measuring.

Do not touch any object that 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 withstanding the voltage being

measured.

The instrument and accessories must be used in accordance with its
specifications and operating instructions or the safety of the equip­ment may be impaired.

The WARNING heading in a manual explains dangers that might
result in personal injury or death. Always read the associated infor­mation very carefully before performing the indicated procedure.

Do not exceed the maximum signal levels of the instruments and ac­cessories, as defined in the specifications and operating informa­tion, and as shown on the instrument or test fixture panels, or

switching card.
When fuses are used in a product, replace with same type and rating

for continued protection against fire hazard.

Chassis connections must only be used as shield connections for

measuring circuits, NOT as safety earth ground connections.

If you are using a test fixture, keep the lid closed while power is ap-

plied to the device under test. Safe operation requires the use of a

lid interlock.

Ifa@

screw is present, connect it to safety earth ground using the

wire recommended in the user documentation.

The ! a symbol on an instrument indicates that the user should re-

fer to the operating instructions located in the manual.

The A symbol on an instrument shows that it can source or mea-

sure 1000 volts or more, including the combined effect of normal
and common mode voltages. Use standard safety precautions to
avoid personal contact with these voltages.

The CAUTION heading in a manual explains hazards that could
damage the instrument. Such damage may invalidate the warranty.

Instrumentation and accessories shall not be connected to humans.

Before performing any maintenance, disconnect the line cord and
all test cables.

To maintain protection from electric shock and fire, replacement
components in mains circuits, including the power transformer, test
leads, and input jacks, must be purchased from Keithley Instru­ments. Standard fuses, with applicable national safety approvals,
may be used if the rating and type are the same. Other components
that are not safety related may be purchased from other suppliers as
long as they are equivalent to the original component. (Note that se­lected parts should be purchased only through Keithley Instruments
to maintain accuracy and functionality of the product.) If you are

unsure about the applicability of a replacement component, call a
Keithley Instruments office for information.

To clean the instrument, use a damp cloth or mild, water based

cleaner. Clean the exterior of the instrument only. Do not apply
cleaner directly to the instrument or allow liquids to enter or spill
on the instrument.

Rev. l/99

HOW TO USE THIS MANUAL

Details procedures to verify that the instrument meets
stated specifications.

r

Describes basic operating principles for the varicws circuits in
the Model 3330.

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.

SECTlON 1

Performance Verification

SECTION 2

Principles of Operation

SECTION 3

Service Information

Table of Contents

SECTION 1

1.1

1.2

1.3

1.4

1.5

1.5.1

1.5.2

1.5.3

1.5.4

15.5

1.5.6

15.7

1.5.8 ExternalDCBiasVoltageRange .................................................

1.6

1.6.1

1.6.2 RecommendedEquipment

1.6.3

1.6.4

1.6.5

1.6.6

- Performance Verification

~ODU~ON

lJ?XIULCONDlTIONS ......................................................... l-l

LINEPOWER
VERIFIcATlONLIMITs

MEASUREMENTSIGNALTESTS .................................................

EnvironmentalConditions
Recommended Test Equipment

FrequencyAccuracy.. ........................................................

Measurement Signal Level Accuracy
Measurement Signal Distortion
OutputImpedanceAc~a~
Internal Bias Voltage Accuracy

MEAsuREMENTACcuRAcyTESTS.. ............................................

EnvironmentiCondiiions

Recommended Standards Accuracy
Resistance Measurement Accuracy

Capa~~ceReadingChecks.......................................-

InductanceReadingChecks ....................................................

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

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

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

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

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

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

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

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

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

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

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

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

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

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

l-l

l-l
l-l
l-2
l-2
l-2
l-3
l-3
l-4
l-4
l-6
1-6
l-7
l-7
l-7
l-7
l-8
l-11
l-11

SECTION 2 - Principles of Operation

2.1

2.2 BLOCKDLAGRAMS

2.3 CURRENT AND VOLTAGE DETECTION

2.4

2.5

2.6 CURRENT-TO-VOLTAGE CONVERTER

2.7

INTRoDucTON......................................-....~.............~

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

lMl?EDANCECALCULATION

O!XlLLATOR

ANALYZER.. ................................................................

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

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

SECTION 3 - Service Information

3.1

3.2

3.2s

32.2'

3.3

3.4

3.5

3.5.1

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

FUSEREPLA

LineFuse ..................................................................

ExternalBiasFuse......................-

CALIBlUTiON ...............................................................

FANmLTERCLEANING ........................................................

REl?AIR

FactoryService.. ............................................................

CEMENT ..........................................................

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

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

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

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

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

.....

2-l
2-l
2-l
2-l

2-4
2-5
2-5

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

3-2

3.5.2

3.5.3 BatteryReplacement ..........................................................

3.5.4 OperationCheckProcedure

3.5.5 RepairS~ary

3.6

3.6.1 PartsList

3.6.2

CoverRemoval............................................................-. 3-2

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

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

RIZLKEABLEPARTS

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

OrderingParts

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

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

APPENDICES

A specifications

3-2
3-4

3-4
3-5
3-5
3-5

List of Tables

SECTION 1 - Performance Verificatibn

Table l-1
Table l-2 Distortion Measurement Summary
Table l-3
Table l-4 Resistance &Ieasurement Accuracy Reading Limits ( I Z I ) for 1Vrm.s Level
Table l-5 Resistance Measurement Accuracy Reading Limits (9) for 1Vrms Level
Table l-6 Resistance Measurement Accuracy Reading Limits ( I Z I ) for 5OVrms Level
Table l-7

Recommended Test Equipment for Measurement Signal Tests

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

Recommended Equipment for Measurement Accuracy Tests

Resistance Measurement Accuracy Reading Limits (0) for 5OVrms Level

........................ l-2

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

................. 3-10

................ 3-10

SECTION 3 - Service Information

Table 3-l RecommendedLineFuse
Table 3-2
Table 33
Table 3-4 Measurement Signal Problem Summary

Table 35 Model 3330 Replaceable Parts

Se~-calibrationErr ......................................................

Operation Check Problem Summary

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

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

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

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

l-4
l-8

............... l-9

.............. 3-10

3-l
3-4

3-4
3-5

3-6

List of Illustrations

SECTION l-

Figure 1-l
Figure l-2 Connections for Frequency Accuracy Measurement
Figure l-3 . Connections for Distortion Measurements
Figure l-4
Figure l-5
Figure l-6

Figure l-7
Figure l-8 Connections for Capacitance and Inductance Reading Checks

Performance Verification

Connections for Measurement and Signal Level Accuracy

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

Connections for Output Impedance Tests
Connections for DC Bias Accuracy Tests
Connections for External DC Bias Voltage Range Test

Connections for Resistance Accuracy Measurements

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

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

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

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

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

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

SECTION 2 - Principles of Operation

Figure 2-l
Figure 2-2
Figure 2-3
Figure 2-4
Figure 2-5

Measuring System Block Diagram

Hardware Block Diagram
Oscillator Block Diagram
Current-to-Voltage Converter
Analyzer

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

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

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

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

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

SECTION 3 - Service Information

Figure 31
Figure 32

CoverRemoval..................................................-........ 3-3

Model 3330 Exploded View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . . . _ . . . . . . . .

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

.........

.,

l-3
l-4
l-5
1-5
l-6
l-7

l-9
l-12

2-2
2-3
24
2-5
2-6

3-7

SECTION 1

Performance Verification

1 .l INTRODUCTION

The procedures outlined in this section may be used to
verifythattheModel333oLcZMeterisoperatingwithin
Emits stated in the specScations. 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.

NOTE
If instrument performance is outside the
specified range, and the instrument is still un­der warranty, contact your Keithley represen­tative or the factory to determine the correct
course of action.

Performance verification fahs into the foIlowing two gen­eral categories:

1.2 INITIAL CONDITIONS

The Model 3330 should be turned on and allowed to
warm up for at least one-half hour before performing the
verification procedures. (The test equipment should also
beallowedtowarmupforthetimeperiodrecommended
by the manufacturer..) If the instrument has been sub­jected to extreme temperature or humidity, allow addi­tional time for internal circuits to reach normal operating
temperature. Typically, it takes one additional hour to
stabilize a unit that is 10°C (Wl?,I outside the specified
temperature range.

1.3 LINE POWER

Be sure to set the line voltage switch on the rear panel to
the correct line voltage. The instrument should be tested
while operating on a line voltage within +5% of the line
voltage switch setting and at a line frequency from 48Hz
to 62Hz.

1.4 VERIFICATION LIMITS

l

Measurement signal tests (paragraph 1.5)

l

Measurement accuracy and reading checks (para-

graph 1.6)

The performance verification limits stated in this section
reflect only the accuracy specifications of the Model 3330.
They do not include test equipment tolerance.

1-l

SECTION 1
Performance Verification

1.5 MEASUREMENT SIGNAL TESTS

Measurement signal tests measure various characteris­tics of the test signal that is applied to the DTJT. These
tests include:

l Frequency accuracy

. Measurement signal level accuracy

l

Measurement signal distortion

0 Output impedance accuracy

l li&mal

* External DC bias voltage range

Manufacturer Model

Keithley 197A DMM (AC volts,

DC bias voltage accuracy

Table l-l. Recommended Test Equipment for Measurement Signal Tests

Description

DC volts, 5-l /2 digits)

1.51 Environmental Conditions

All measurement signal tests should be performed at an

ambienttemperatureof23”+5”Candatarelativehumid­ity of 50% + 30%.

IS.2 Recommended Test Equipment

Table l-l lists the test equipment required to perform the
measurement signal tests. The procedures for measure­ment signal verification tests are based on using this ex­act equipment. Alternate equipment may be used as long
as ihat equipment has specifications at least good as
those stated in Table l-l.

Specifications

2VDC range; +(O.Oll% of rdg + 2 counts)
2VAC range; z!$O.35% of rdg + 100 counts)

Philips

PM 6654C Timer/counter
PM 9678

Panasonic

Keithley

Keithley

VP-772Z4 Audio analyzer

1681 Test leads

7051-2

Keithley 7754-3
Keithley
Keithley
Pomona

3324
3325
1468

TCXO option

DC power supply

BNC interconnect cable

BNC to alligator cable
Test leads
Test leads
BNC-banana adapter

Capacitor
Resistor
switch

O.OlHz-12OMHz; time base aging
<l x 10-7/month

lOI&-1lOkHz; 0.01% accuracy at full scale; _+ldB har­monic distortion accuracy from lOH2 to 15.99kHz
04OVDC adjustable, <5mVp-p ripple

Two leads terminated with banana plug and clip-on
probes

5OQ coaxial cable (RG58C), male BNC connectors, 2ft.

(0.6m)

Coaxial cable, male BNC connector, two alligator clips

4-terminal alligator clip test lead set

Kelvin clip test lead set

Female BNC connector to double banana plug

lo@?, 1oOVDC
100Q &o-5%, 1/2w
Single-pole, single-throw

l-2

Pt7jinmance Verification

SECTION1

1 s.3 Frequency Accuracy

1. ConnecttheModel333OHCURjacktoinputAofthe
counter/timer, as shown in Figure l-l. Be sure to
co~ect the G terminal of the LCZ meter to the shield
of the connecting cable as shown

2. Set the LCZ meter operating modes as follows:
FREQ: 1kH.z

LEVELZ 1vrms
BIAS: OFF

3. set the counter/timer to measure frequency on in­PUt JJ-

4. Verify that the counter reading is between

0.99995OkHz and 1.00005OkHz &!Spprn~.

1.5.4 Measurement Signal Level
Accuracy

1. Conned the Model 3330 H CUR jack to the DMM, as
shown in Figure l-2. be sure to connect the G termi-

nal of the LCZ meter. to the shield of the connecting
cable as shown.

2. Select the ACV function and auto-ranging on the
DMU

3. Set the LCZ meter operating modes as follows:

LEVEL: 1vrms
FREQ: 1kHz
BLAS: OFF

4. Verify that the DMM reading is between the limits
for lVrms, lkH2 operation, as follows:

0.97vrms to 1.03vrms (23.0%).

5. Change the LEVEL to 5OmVrms, and verify the sig­nal level accuracy for lkHz,5OmVrm.s operation is
as follows:

47.5mVrms to.52.5mVrms (&!S.O%)

Figure z-1.

Model 3330

to cable
shield

Connections

Model 7051-2 Coaxial Cable

for

Measurement and Signal Level Accuracy

l-3

SEcnONl

Pe?yinmance vm.fication

/i I-’

Figure z-2.

Model 3330

*

L

Connect G terminal

to cable shield

Gmnecfionsfar Frequency Accuracy Measurml

/

1

1.55 Measurement Signal Distortion

1. Connect the H CUR jack of the LCZ meter to the dis­tortion meter, as shown in Figure 13. Be sure to con­nect the G terminal of the LCZ meter to the cable
shield as shown.

2.

Set the LCZ meter operating modes as follows:
LEVEL: 1vrms

BIAS OFF

FREQ lkH.2

3.

Verify that the distortion reading is 0.3% or less, as

summarized in Table l-2.

Model 197A DMM

I

Model 7051-2 Coaxial Cable

C. Press the ENTER/EXlT key twice to complete

2ooHz

7.

Verify that the distortion reading is 0.3% or less.

1 S.6 Output Impedance Accuracy

1. Connect the LCZ meter to the DMM, switch, and re­sistor, as shown in Figure l-4. Be sure that the G ter­minal of the LCZ meter is connected to the cable
shield, and that the resistor and switch are connected
as shown.

2. Select the 2VAC

3.

Set the LCZ meter operating modes as follows:

Pomona 1468

programming.

range on the DMM.

Table l-2. Distortion Measurement Summary

Frequency Distortion Reading

4.

Change the frequency to 1OOkHz.

5.

Verify that the distortion reading is 0.5% or less.

6.

Set the Model 3330 frequency to 2OOHz as follows:

A. Press the SETCTP key to enter the auxiliary setup

mode. The LED

blinks, and the unit displays the present fre­quency in them DISPLAY area.

B. Enter a frequency of 2OOHz.

l-4

above the FREQ (HZ) marking

FREQ lkH2

LEVEL 1vrms
BIAS: OFF

4.

Set the switch to the open position, then note the
DMM reading. Call this reading VI.

5. Set the switch to the closed position, then note the
DMM reading. Call this reading Vz.

6. Compute the output impedance

from

VI and Vz as

follows:
zour = 100

Wl/VZ -

1)

IQ1

7. Verify that the output impedance computed in step 6
is between 97S2 and 10322 inclusive (S%).