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MODEL 602
INSTRUCTION MANUAL
Instruction Manual
Model 602
Solid-State Electrometer
Publication Date: June 1963
Document Number: 29111 Rev. C
Contains Operating and Servicing Information for the
Model 602 Solid-State Electrometer
01975, Keithley Instruments, Inc.
Cleveland, Ohio, U.S.A.
Document Number 29111
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 we warranted for the balance of the origi-
nal warranty period, or at least 90 days.
LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from pmduct 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 WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED HEREIN ARE
BUYER'S SOLE AND EXCLUSIVE REMEDIES.
NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT, INDI-
RECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRUMENTS AND
SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF
SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS OF REMOVAL
AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR DAMAGE TO PROPERTY.
Keithley Instruments, Inc. - 28775 Aurora Road * Cleveland, OH 44139 * 216-248-0400 *Fax: 216-248-6168 * http://www.keithley.com
SPECIFICATIONS
AS A VOLTMETER: may be drawn for input voltages of 10" or less. Output polarity is same as
RANGE: .OOlV full scale to 1OV in nine'lX and 3X ranges. input p&dry.
ACCURACY: f 1% of full scale on all ranges exclusive of noise and drii. VOLTAGE RECORDER OUTPUT: *lV for full-scale input. Internal
ZERO DRIFT: Less than Im" per 24 hours, Ikss than 150@ per OC. resistance is g1M1. Output polarity is opposite input polarity.
METER NOISE: *25&J maxim"m with input shoned on most sensitive Gain: 0.1. 0.33, a.. to 1000.
Frequmw Response lwithin 3db): DC to 40kHr 81 a gain of 1 and
IN?~?iMPEDANCE: Greater than lo'% shunted by2OpF. Input resistance lo&, &e&g to DC to 1OOHz at maximum gain. Full o"tp"t
response limited to 3kHz on any gain.
AS iN AMMETER: Noise: Less than 3% ms of full scale at gain of 1000. decreasing 10 less
RANGE: lCr14A full scale to 0.3A in twenty-eight 1X and 3X ranges. than 0.5% ar gains below 10.
ACCURACY: 12% of full scale on 0.3 to 10"A ranges using the mallest CURRENT RECORDER OUTPUT: i ImA for full-scale input. variable
available multiplier setting; *t4% of full scale on 3 x lo-l2 fo 10-14A f6% wtih 14OOll recorders.
ranoes. GENERAL
METER NOISE: Less than f3 x 10-16A. ISOLATION: Circuit ground to chassis ground: Greater than l@Q shunted
OFFSET CVRRENT: Lens than 5 x 10-15A. by .0016~F. Circuit ground may be floated up to f 15OOV with wpecf to
AS AN OHMMETER: chassis ground.
RANQE: 7000, full scale to 10% in twent+hree linear IX and 3X ranges. Polarity: Meter *witch seIects lefvzero Ipositive or negative) or center-zero
ACCURACY: *3% of full scale on 100 to l@Q ranges using the largest scales. Meter witch does nof reverse polarity of o"fp"tS.
available multiplier stting; f5% of full scale on 3 x 109 to 1O'jn ranges. CONNECTORS: Input: Teflon-insulated tdaxial Bendix 33050-Z. Low:
AS AN COULOMBMETER: Binding post. Voltage or currem o"tp"t: Amphenol 60.PCZF. Unity-gain
RANGE: lo-`? full scale to 10dC in fifteen IX and 3X ranges. o"tp"1, chassis ground: Binding posts.
BATTERY CHECK: Condition of all baneries may be checked with front
ACCURACY: f5% of full scale on all ranges. Dritt due fo offset current
does no, exceed 5 x 10.=C per second. paw co"trok.
BATTERIES: Six 2N6 lor 246. VS306. NEDA 16021: one RM-1W. 1000
AS AN AMPLIFIER:
tNPUT IMPEDANCE: Greater than 10'40 shunted by2OpF. input resistance DIMENSIONS. WEIGHT: Overall bench size 10% in. high x 7 in. wide x
may a,so be ~&cted in decade steps from 10 fo lO"O. 11 `h in. deep 1276 x 175 x 2gOmm). Net weight. 13 pounds l57kgl.
OUTPUTS: Unitygain output and either voltage or cment recorder o"tp"t. ACCESSORIES SUPPLIED: Model 6011 Input Cable: 30" triaxial cable
UNITY-QAIN OUTPUT: At DC, o"tp"t is equal to input within 10 ppm. ex- with friaxial connector and 3 alligator clips. Mating o"tp"f connector.
clusive of noise and drib?. for o"tp"t currents of lOO@ or less. Up 10 ImA
TABLE OF CONTENTS
Paragraph Title Page
SECTION l-GENERAL DESCRIPTION
1.1 Introduction ........................... ................ ............. ......... 1-l
1.2 Model 602 Features. .................... ................ ............. ...... .. l-l
1.3 Warranty Information ................... ................ ......... l-l
1.4 ManualAddenda ....................... ................ ............. ......... l-l
1.5 Safety Symbols and Terms. .............. ................ ............. ......... l-1
1.6 Safety Precautions ..................... ................ ............. l-l
1.7 Specifications ......................... ................ ............. ......... 1-2
1.8 Optional Accessories. ................... 1-2
1.8.1 Model 6101A Shielded Probe ........... ................ ............. ......... 1-2
1.82 Model 6103C Divider Probe ............ ................ ............. 1-2
1.8.3 Model 6104Test Shield. ............... ................ ............. ......... 1-2
1.8.4 Model 6105 Resistivity Chamber ........ ................ 1-2
1.8.5 Model 2503 Static Detector Probe. ...... ......... 1-2
1.8.6 Model 6011 Input Cable ............... ................ ............. ......... 1-2
1.8.7 Model 6012 Triax-to-Coax Adapter ...... ................ ............. 1-2
SECTION Z-OPERATION
2.1 Introduction .......................... ............. ...... 2-1
2.2 Front Panel Controls ................... ............. ...... ...... 2-l
2.3 Rear Panel Terminals. .................. ...... ...... 2-l
2.4 Input Connections ..................... ............. ...... ...... 2-l
2.5 Preliminary Procedures. ................ ............. ...... ...... 2-4
2.6 Voltage Measurements. ................ ...... 2-5
2.6.1 Normal Method Voltage Measurements ............. ...... ...... 2-5
2.6.2 Guard Method Voltage Measurements ............. ...... ...... 2-5
2.6.3 Low Impedance Source .............. ............. ...... ...... 2-5
2.7 Off-Ground Voltage Measurements ....... ............. ...... 2-5
2.7.1 FEEDBACK Switch Set To NORMAL ... ............. ...... ...... 2-5
2.7.2 FEEDBACK Switch Set To FAST ...... ............. ...... 2-5
2.8 Current Measurements ................. ............. ...... ...... 2-6
2.8.1 Normal Mode IO.3 to lO~`4A Ranges) .... ...... 2-6
2.6.2 Fast Method (Current Below lo-=A) .... ............. ...... ...... 2-6
2.8.3 Galvanometric Method ............... ............. ...... 2-7
2.9 Resistance Measurements .............. ...... 2-7
2.9.1 Normal Constant Current Method ...... ............. ...... ...... 2-7
2.9.2 Fast Constant Current Method. ........ ............. ...... ...... 2-8
2.9.3 Voltmeter-Ammeter Method (To 10%) ............. ...... 2-8
2.10 Charge Measurements ................. ............. ...... 2-8
2.11 Recorder Outputs ..................... ............. ...... ...... 2-9
2.12 Unity-Gain Output ..................... ............. ...... ...... 2-9
SECTION 3-THEORY OF OPERATION
3.1 Introduction .......................... ...... ...... ...... ............. 3-l
3.2 Voltmeter Operation ................... ...... ...... ...... ............. 3-1
3.3 Voltmeter Circuit ...................... 3-l
3.4 Ammeter Operation. ................... ...... ...... ............. 3-1
3.4.1 Normal Method ..................... ...... ...... ............. 3-l
3.4.2 Fast Method. ....................... ...... ...... ............. 3-2
3.5 Ohmmeter Operation .................. ...... ............. 3-2
3.5.1 Normal Method ..................... ...... ............. ...... 3-2
3.5.2 Guarded Method .................... ...... ,,.... .,.... ............. 3-2
3.6 Coulombmeter Opration ................ ...... ............. ...... 3-2
SECTION 4--SERVICING INFORMATION
4.1 Introduction ................................................................................... 41
4.2 Calibration .................................................................................... 4-l
4.2.1 RecommendedEquipment ..................................................................... 4-l
4.2.2 CalibrationSchedule .......................................................................... 4-l
4.3 Preliminary Procedures .......................................................................... 4-l
4.4 Mechanical Meter Set and Meter Zero Calibration .................................................... 4-2
4.5 Tracking Check and 1MA Output Calibration ........................................................ 4-2
4.6 NoiseCheck ................................................................................... 4-2
4.7 OffsetCurrentCheck ...........................................................................
4.8 DrinCheck .................................................................................... z
4.9 High-Megohm ResistorVerification. ............................................................... 4-3
4.10 AccuracyCheck ............................................................................... 4-3
4.10.1 VoltageAccuracyCheck ....................................................................... 43
4.10.2 CurrentAccuracyCheck .......................................................................
4.10.3 ResistanceAccuracyCheck .................................................................... 2
4.10.4 ChargeAccuracyCheck ....................................................................... 4-4
4.11 Unity-GainCheck ..............................................................................
4.12 FrequencyResponseCheck ...................................................................... zl
4.13 CommonModeRejectionCheck .................................................................. 4.4
4.14 Troubleshooting ............................................................................... 45
4.14.1 Servicing Schedule ...........................................................................
4.14.2 Par&Replacement ........................................................................... z
4.15 Procedures To Guide Troubleshooting ............................................................. 4.2
4.16 Servicing High Impedance Circuitry ................................................................ 4-6
SECTION S-REPLACEABLE PARTS
5.1 Introduction ................................................................................... 5-l
5.2 PartsList ..................................................................................... 5-l
5.3 OrderingInformation ............................................................................ 51
5.4 FactoryService ................................................................................ 5-l
5.5 Special Handling of Static Sensitive Devices ........................................................ 51
5.6 ComponentLocationDrawing .................................................................... 51
r*
5.7 SchematicDiagram.........................,.,.............,,..,............................... o-1
ii
LIST OF FIGURES
Figure Title Page
2-1 Model 602 Front Panel Controls .......................................... ................ ......... 2-2
2-2 Model 602 Rear Panel Terminals .......................................... ................ ......... 2-3
2-3 Triaxiallnput .......................................................... ................ ......... 2-4
2-4 Error Due to Ammeter Resistance. ........................................ ................ ......... 2-6
2-5 Measuring Current by the Galvanometric Method, ........................... ................ ......... 2-7
2-6 Measuring Resistance by the External Voltage Method ....................... ................ ......... 2-8
2-7 Divider Curcuits ccross Model 602 Output for Driving 50 and 10OmV Recorders ... ................ ......... 2-9
2-8 Measuring Potential of Hich Resistance Source with 0.025% Accuracy. ......... ................ ......... 2-9
3-1 Block Diagram of Model 602 in Voltmeter Mode ............................. ................ ......... 3-l
3-2 Block Diagram of Model 602as a Picoammeter .............................. ................ ......... 3-2
3-3 Block Diagram of Model 602for Normal Method Measuring Resistance ......... ................ ......... 3-2
4-l Model 602 Case to LO Isolation Check ..................................... ................ ......... 4-2
4-2 Model 602 Unity-Gain Test Set-Up. ....................................... ................ ......... 4-4
5-1 Model 602 Chassis, Side View. ........................................... ................ ......... 5-2
5-2 RANGE Switch, S102, Component Location Drawing ........................ ................ ......... 53
5-3 MULTIPLIER Switch, S106, Component Location Drawing ................... ................ ......... 53
5-4 Model 602, PC186, Component Location Drawing ........................... ................ 57
5-5 Model 602, PC127, Component Location Drawing ........................... ................ ......... 5-7
5-6 Model 602, Schematic Diagram, Dwg. No. 21174E .......................... ................ ......... 5-9
LIST OF TABLES
Table Title Page
2-l Color Coding of Alligator Clips for Model 6011 Input Cable ... 2-l
2-2 Multiplier Switch Positions for Checking .................. ...... ...... ...... 2-4
4-1 Recommended Test Equipment ......................... ...... ...... ...... 4-l
4-2 Model 602 Internal Controls. ............................ ...... ...... 4-2
4-3 Coulomb Ranges Accuracy Check ....................... 4-4
4-4 Model 602 Troubleshooting. ............................ ...... ...... ..,... 4-5
5-l Model 602 Static Sensitive Devices ...................... ...... ...... 5-l
5-2 Model 602 Replaceable Parts List ........................ ...... 54
iii/iv
SECTION 1
GENERAL DESCRIPTION
1.1 INTRODUCTION 1.3 WARRANTY INFORMATION
The Keithley Model 602 Electrometer is a completely solid- Warranty information may be found inside the front cover of
state, battery operated instrument, which measures a wide this manual. Should it become necessary to exercise the
range of DC voltage, current, resistance and charge. The warranty, contact your nearest Keithley representative or the
Model 602's input resistance of greater than 10'4R is the factory to determine the correct course of action. Keithley
result of extensive instrument development with high input Instruments maintains service facilities in the United States,
impedance transistors. The Model 602 has all the capabilities West Germany, Great Britain, France, the Netherlands,
of conventional VTVMs, but can also make more measure- Switzerland, and Austria. Information concerning the appli-
ments without loading circuits. cation, operation, or service of your instrument may be
directed to the applications engineer at any of these loca-
The Model 602 has nine voltage ranges from O.OOlV full scale tions. Check the inside front cover of this manual for ad-
to lOV, 28 current ranges from 10'4A full scale to 0.3A. 23 dresses.
linear resistance ranges from 1000 full scale to 1OtQ. and 15
charge ranges from lo-`SC full scale to lo-aC. 1.4 MANUAL ADDENDA
The Model 602 offers complete line isolation and excellent Information concerning improvements or changes to the
off-ground measuring capability. Up to 1500V may be applied instrument which occur after the printins o! this manual will
between the input low terminal and the case, and stage be found on an addendum sheet included .-:ith this manual.
operation is assured with the case grounded. A triaxial con- Be sure to review these changes before ar:en:$ing to operate
nectar allows complete guarding of the high impedance input or service the instrument.
terminal.
1.5 SAFETY SYMBOLS AND TERMS
The Model 602 employs matched insulated-gate field-effect
transistors followed by transistor differential amplifier stages The following safety symbols and terms are used in this
and a compliritentary-output stage. A large amount of manual or found on the Model 602.
negative feedback is used for stability and accuracy.
The symbol A on the instrument indicates that the user
1.2 MODEL 602 FEATURES should refer to the operating instructions in this ;nanual.
1. The Model 602 has excellent zero stability which permits The symbol # on the instrument indicates that a po-
accurate measurements with minimal adjustment. Short tential of 1OOOVor more may be present on the terminaltsl.
term zero drift is less than 50& per hour. Zero offset due Standard safety precautions should be observed when such
to temperature change is less than 15O/rV per OC after 30 dangerous voltages are encountered.
minute warm-up period. This offset, however, can easily
be compensated for with the front panel zero controls. The WARNING heading in this manual explains dangers that
could result in personal injury or death.
2. Fast warm-up is an inherent characteristic of the Model
602. It can be operated 30 minutes after warm-up on the
The CAUTION heading in this manual explains hazards that
most sensitive range and almost immediately on less sensi-
could damage the instrument.
tive ranaes.
3. Low offset current 5 X lo-IsA, minimizes zero offset with 1.6 SAFETY PRECAUTIONS
high source resistance and permits maximum resolution
when measuring current and charge. 1. This instrument is intended for use by qualified personnel
4. The 1000 hour life of the batteries enables usage in long who recognize the shock hazards and are familiar with the
term experiments without interruptions for recharging. safety precautions required to avoid possible injury. Read
Battery life is maintained even when the 1OmA recorder over the manual carefully before operating this instrument.
output is used. For further convenience, battery condition 2. Excercise extreme caution when a shock hazard is present
is readily checked on the panel meter. at the instrument's input. The American National
5. Excellent overload protection without degradation of per- Standards Institute (ANSI) states that a shock hazard ex-
formance is obtained by use of a unique input circuit. The ists when voltage levels greater than 30V rms or 42.4V
Model 602 Electrometer will withstand damage and has peak are present. A good safety practice is to expect that
good recovery. hazardous voltage is present in any unknown circuit before
measuring.
l-l
3. Inspect the test leads for possible wear, cracks or breaks Three-Terminal Connections-The GUARD output on the
before each use. If any defects are found, replace with test Model 602 Electrometer can be used for resistance
leads that have the same measure of safety as those sup- measurements where the effects of cable capacitance may be
plied with the instrument. significant. Connect the unknown between INPUT and EXT
4. For optimum safety do not touch the test leads or the terminals. Connect the EXT terminal to the GUARD output
instrument while power is applied to the circuit under test. on the electrometer. Use the electrometer in fast mode for
Turn the power off and discharge all capacitors, before ohms measurement.
connecting or disconnecting the instrument.
5. Do not touch any object which could provide a current I.E.4 Model 6105 Resistivity Chamber
path to the common side of the circuit under test or power
line (earth) ground. Always make measurements with dry The Model 6105 is a guarded test fixture for measurement of
hands while standing on a dry, insulated surface, capable surface and volume resistivities. The chamber is designed in
of withstanding the voltage being measured. accordance with ASTM Standard Method of Test for Electri-
6. Exercise extreme safety when testing high energy power cal Resistance of Insulated Materials, D257-66. The Model
circuits (AC line or mains, etc). Refer to the operating 6105 can be used in conjunction with an electrometer and
section. voltage supply.
7. Do not exceed the instrument's maximum allowable input Resistivity can be determined by measuring the current
as defined in the specifications and operation section. through a sample with a known voltage impressed. The
measurement can be made most conveniently when a set of
1.7 SPECIFICATIONS electrodes are used which can be calibrated in terms of
surface or volume resistivity. The Model 6105 has been
Detailed Model 602 specifications may be found immediately designed for use with a Keithley electrometer and an optional
preceding this section. high voltage supply such as the Model 247.
1.8 OPTIONAL ACCESSORIES 1.8.5 Model 2503 Static Detector Probe
The following optional accessories can be used with the Model 2503 is designed to detect voltage due to charge on
Model 602 to provide additional convenience and versatility. relatively small surface areas. Solid coaxial 13mm (% inch)
diameter tube used with 89mm (3% inch) head, 89mm (3%
1.8.1 Model 8lOlA Shielded Probe inch) coupler, 25mm (one inch) adapter and two 90