Keithley 602 User manual

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 aperiod of 1year 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. - 28775Aurora Road* Cleveland, OH 44139 * 216-248-0400 *Fax: [phone] * http://www.keithley.com

SPECIFICATIONS
AS A VOLTMETER:
RANGE: .OOlV full scale to 1OVin nine’lX and 3X ranges.
ACCURACY: f 1% of full scale on all ranges exclusive of noise and drii.
ZERO DRIFT: Less than Im” per 24 hours, Ikss than 150@ per OC.
METER NOISE: *25&J maxim”m with input shoned on most sensitive
IN?~?iMPEDANCE: Greater than lo’% shunted by2OpF. Input resistance
AS iN AMMETER:
RANGE: lCr14A full scale to 0.3A in twenty-eight 1X and 3X ranges.
ACCURACY: 12% of full scale on 0.3 to 10”A ranges using the mallest
available multiplier setting; *t4% of full scale on 3 x lo-l2 fo 10-14A
ranoes.
METER NOISE: Less than f3 x 10-16A.
OFFSET CVRRENT: Lens than 5 x 10-15A.
AS AN OHMMETER:
RANQE: 7000, full scale to 10% in twent+hree linear IX and 3X ranges.
ACCURACY: *3% of full scale on 100 to l@Q ranges using the largest
available multiplier stting; f5% of full scale on 3 x 109to 1O’jn ranges.
AS AN COULOMBMETER:
RANGE: lo-‘? full scale to 10dC in fifteen IX and 3X ranges.
ACCURACY: f5% of full scale on all ranges. Dritt due fo offset current
does no, exceed 5 x 10.=C per second.
AS AN AMPLIFIER:
tNPUT IMPEDANCE: Greater than 10’40 shunted by2OpF. input resistance
may a,so be ~&cted in decade steps from 10 fo lO”O.
OUTPUTS: Unitygain output and either voltage or cment recorder o”tp”t.
UNITY-QAIN OUTPUT: At DC, o”tp”t is equal to input within 10 ppm. ex-
clusive of noise and drib?.for o”tp”t currents of lOO@ or less. Up 10 ImA
may be drawn for input voltages of 10” or less. Output polarity is same as
input p&dry.
VOLTAGE RECORDER OUTPUT: *lV for full-scale input. Internal
resistance is g1M1. Output polarity is opposite input polarity.
Gain: 0.1. 0.33, a.. to 1000.
Frequmw Response lwithin 3db): DC to 40kHr 81 a gain of 1 and
lo&, &e&g to DC to 1OOHz at maximum gain. Full o”tp”t
response limited to 3kHz on any gain.
Noise: Less than 3% ms of full scale at gain of 1000. decreasing 10 less
than 0.5% ar gains below 10.
CURRENT RECORDER OUTPUT: i ImA for full-scale input. variable
f6% wtih 14OOll recorders.
GENERAL
ISOLATION: Circuit ground to chassis ground: Greater than l@Q shunted
by .0016~F. Circuit ground may be floated up to f 15OOVwith wpecf to
chassis ground.
Polarity: Meter *witch seIects lefvzero Ipositive or negative) or center-zero
scales. Meter witch does nof reverse polarity of o”fp”tS.
CONNECTORS: Input: Teflon-insulated tdaxial Bendix 33050-Z. Low:
Binding post. Voltage or currem o”tp”t: Amphenol 60.PCZF. Unity-gain
o”tp”1, chassis ground: Binding posts.
BATTERY CHECK: Condition of all baneries may be checked with front
paw co”trok.
BATTERIES: Six 2N6 lor 246. VS306. NEDA 16021: one RM-1W. 1000
DIMENSIONS. WEIGHT: Overall bench size 10% in. high x 7 in. wide x
11‘h in. deep 1276 x 175 x 2gOmm). Net weight. 13 pounds l57kgl.
ACCESSORIES SUPPLIED: Model 6011 Input Cable: 30” triaxial cable
with friaxial connector and 3 alligator clips. Mating o”tp”f connector.

TABLE OF CONTENTS
Paragraph Title Page
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.8.1
1.82
1.8.3
1.8.4
1.8.5
1.8.6
1.8.7
2.1
2.2
2.3
2.4
2.5
2.6
2.6.1
2.6.2
2.6.3
2.7
2.7.1
2.7.2
2.8
2.8.1
2.6.2
2.8.3
2.9
2.9.1
2.9.2
2.9.3
2.10
2.11
2.12
3.1
3.2
3.3
3.4
3.4.1
3.4.2
3.5
3.5.1
3.5.2
3.6
SECTION l-GENERAL DESCRIPTION
Introduction ...........................
Model 602 Features. ....................
Warranty Information ...................
ManualAddenda .......................
Safety Symbols and Terms. ..............
Safety Precautions .....................
Specifications .........................
Optional Accessories. ...................
Model 6101A Shielded Probe ...........
Model 6103C Divider Probe ............
Model 6104Test Shield. ...............
Model 6105 Resistivity Chamber ........
Model 2503 Static Detector Probe. ......
Model 6011 Input Cable ...............
Model 6012 Triax-to-Coax Adapter ......
SECTION Z-OPERATION
Introduction ..........................
Front Panel Controls ...................
Rear Panel Terminals. ..................
Input Connections .....................
Preliminary Procedures. ................
Voltage Measurements. ................
Normal Method Voltage Measurements
Guard Method Voltage Measurements
Low Impedance Source ..............
Off-Ground Voltage Measurements .......
FEEDBACK Switch Set To NORMAL ...
FEEDBACK Switch Set To FAST ......
Current Measurements .................
Normal Mode IO.3to lO~‘4ARanges) ....
Fast Method (Current Below lo-=A) ....
Galvanometric Method ...............
Resistance Measurements ..............
Normal Constant Current Method ......
Fast Constant Current Method. ........
Voltmeter-Ammeter Method (To 10%)
Charge Measurements .................
Recorder Outputs .....................
Unity-Gain Output .....................
SECTION 3-THEORY OF OPERATION
Introduction ..........................
Voltmeter Operation ...................
Voltmeter Circuit ......................
Ammeter Operation. ...................
Normal Method .....................
Fast Method. .......................
Ohmmeter Operation ..................
Normal Method .....................
Guarded Method ....................
Coulombmeter Opration ................
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1-l
l-l
l-l
l-l
l-1
l-l
1-2
1-2
1-2
1-2
1-2
1-2
1-2
1-2
1-2
2-1
2-l
2-l
2-l
2-4
2-5
2-5
2-5
2-5
2-5
2-5
2-5
2-6
2-6
2-6
2-7
2-7
2-7
2-8
2-8
2-8
2-9
2-9
3-l
3-1
3-l
3-1
3-l
3-2
3-2
3-2
3-2
3-2

4.1
4.2
4.2.1
4.2.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.10.1
4.10.2
4.10.3
4.10.4
4.11
4.12
4.13
4.14
4.14.1
4.14.2
4.15
4.16
5.1
5.2
5.3
5.4
5.5
5.6
SECTION 4--SERVICING INFORMATION
Introduction ...................................................................................
Calibration ....................................................................................
RecommendedEquipment .....................................................................
CalibrationSchedule ..........................................................................
Preliminary Procedures ..........................................................................
Mechanical Meter Set and Meter Zero Calibration ....................................................
Tracking Check and 1MA Output Calibration ........................................................
NoiseCheck ...................................................................................
OffsetCurrentCheck ...........................................................................
DrinCheck ....................................................................................
High-Megohm ResistorVerification. ...............................................................
AccuracyCheck ...............................................................................
VoltageAccuracyCheck .......................................................................
CurrentAccuracyCheck .......................................................................
ResistanceAccuracyCheck ....................................................................
ChargeAccuracyCheck .......................................................................
Unity-GainCheck ..............................................................................
FrequencyResponseCheck ......................................................................
CommonModeRejectionCheck ..................................................................
Troubleshooting ...............................................................................
Servicing Schedule ...........................................................................
Par&Replacement ...........................................................................
Procedures To Guide Troubleshooting .............................................................
Servicing High Impedance Circuitry ................................................................
SECTION S-REPLACEABLE PARTS
Introduction ...................................................................................
PartsList .....................................................................................
OrderingInformation ............................................................................
FactoryService ................................................................................
Special Handling of Static Sensitive Devices ........................................................
ComponentLocationDrawing ....................................................................
41
4-l
4-l
4-l
4-l
4-2
4-2
4-2
z
4-3
4-3
43
2
4-4
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4.4
45
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4.2
4-6
5-l
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51
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5.7 SchematicDiagram.........................,.,.............,,..,............................... o-1
ii

LIST OF FIGURES
Figure Title Page
2-1 Model 602 Front Panel Controls .......................................... ................
2-2 Model 602 Rear Panel Terminals .......................................... ................
2-3 Triaxiallnput .......................................................... ................
2-4 Error Due to Ammeter Resistance. ........................................ ................
2-5 Measuring Current by the Galvanometric Method, ........................... ................
2-6 Measuring Resistance by the External Voltage Method ....................... ................
2-7 Divider Curcuits ccross Model 602 Output for Driving 50 and 10OmV Recorders ... ................
2-8 Measuring Potential of Hich Resistance Source with 0.025% Accuracy. ......... ................
3-1 Block Diagram of Model 602 in Voltmeter Mode ............................. ................
3-2 Block Diagram of Model 602as a Picoammeter .............................. ................
3-3 Block Diagram of Model 602for Normal Method Measuring Resistance ......... ................
4-l Model 602 Caseto LO Isolation Check ..................................... ................
4-2 Model 602 Unity-Gain Test Set-Up. ....................................... ................
5-1 Model 602 Chassis, Side View. ........................................... ................
5-2 RANGE Switch, S102, Component Location Drawing ........................ ................
5-3 MULTIPLIER Switch, S106, Component Location Drawing ................... ................
5-4 Model 602, PC186, Component Location Drawing ........................... ................
5-5 Model 602, PC127, Component Location Drawing ........................... ................
5-6 Model 602, Schematic Diagram, Dwg. No. 21174E .......................... ................
LIST OF TABLES
Table Title
2-l Color Coding of Alligator Clips for Model 6011 Input Cable ...
2-2 Multiplier Switch Positions for Checking ..................
4-1 Recommended Test Equipment .........................
4-2 Model 602 Internal Controls. ............................
4-3 Coulomb Ranges Accuracy Check .......................
4-4 Model 602 Troubleshooting. ............................
5-l Model 602 Static Sensitive Devices ......................
5-2 Model 602 Replaceable Parts List ........................
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......... 3-2
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57
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Page
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2-4
4-l
4-2
4-4
4-5
5-l
54
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SECTION 1
GENERAL DESCRIPTION
1.1 INTRODUCTION 1.3 WARRANTY INFORMATION
The Keithley Model 602 Electrometer is a completely solid-
state, battery operated instrument, which measures a wide
range of DC voltage, current, resistance and charge. The
Model 602’s input resistance of greater than 10’4R is the
result of extensive instrument development with high input
impedance transistors. The Model 602 has all the capabilities
of conventional VTVMs, but can also make more measure-
ments without loading circuits.
The Model 602 has nine voltage ranges from O.OOlVfull scale
to lOV, 28 current ranges from 10’4A full scale to 0.3A. 23
linear resistance ranges from 1000 full scale to 1OtQ. and 15
charge ranges from lo-‘SC full scale to lo-aC.
Warranty information may be found inside the front cover of
this manual. Should it become necessary to exercise the
warranty, contact your nearest Keithley representative or the
factory to determine the correct course of action. Keithley
Instruments maintains service facilities in the United States,
West Germany, Great Britain, France, the Netherlands,
Switzerland, and Austria. Information concerning the appli-
cation, operation, or service of your instrument may be
directed to the applications engineer at any of these loca-
tions. Check the inside front cover of this manual for ad-
dresses.
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.
1.2 MODEL 602 FEATURES The symbol A on the instrument indicates that the user
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/rVper OCafter 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
2. Fast warm-up is an inherent characteristic of the Model could result in personal injury or death.
602. It can be operated 30 minutes after warm-up on the
most sensitive range and almost immediately on less sensi- The CAUTION heading in this manual explains hazards that
tive ranaes. could damage the instrument.
3. Low offset current 5 X lo-IsA, minimizes zero offset with
high source resistance and permits maximum resolution
when measuring current and charge.
4. The 1000 hour life of the batteries enables usage in long
term experiments without interruptions for recharging.
Battery life is maintained even when the 1OmA recorder
output is used. For further convenience, battery condition
is readily checked on the panel meter.
5. Excellent overload protection without degradation of per-
formance is obtained by use of a unique input circuit. The
Model 602 Electrometer will withstand damage and has
good recovery.
1.6 SAFETY PRECAUTIONS
1. This instrument is intended for use by qualified personnel
who recognize the shock hazards and are familiar with the
safety precautions required to avoid possible injury. Read
over the manual carefully before operating this instrument.
2. Excercise extreme caution when a shock hazard is present
at the instrument’s input. The American National
Standards Institute (ANSI) states that a shock hazard ex-
ists 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.
l-l

3. Inspect the test leads for possible wear, cracks or breaks
before each use. If any defects are found, replace with test
leads that have the same measure of safety as those sup-
plied with the instrument.
4. For optimum safety do not touch the test leads or the
instrument while power is applied to the circuit under test.
Turn the power off and discharge all capacitors, before
connecting or disconnecting the instrument.
5. 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 withstanding the voltage being measured.
6. Exercise extreme safety when testing high energy power
circuits (AC line or mains, etc). Refer to the operating
section.
7. Do not exceed the instrument’s maximum allowable input
as defined in the specifications and operation section.
1.7 SPECIFICATIONS
Detailed Model 602 specifications may be found immediately
preceding this section.
1.8 OPTIONAL ACCESSORIES
The following optional accessories can be used with the
Model 602 to provide additional convenience and versatility.
1.8.1 Model 8lOlA Shielded Probe
The Model 6010A is a shielded cable with a needle point
probe and 30 inches of low noise cable terminated by a UHF
connector.
I.E.2 Model 8103C Divider Probe
The Model 6013C is a shielded cable with a needle point
probe and 30 inches of low noise cable terminated by a UHF
connector. The probe includes a 1OOO:lvoltage divider with a
4.5 X 1OW input resistance. Accuracy is f5% at 30kV.
1.8.3 Model 8104 Test Shield
The Model 6104 is a shielded test box for two-terminal or
three-terminal connections. The INPUT terminal is Teflon@
insulated.
Two-Terminal Connections-Resistance measurements
can be made conveniently using the INPUT and GROUND
terminals on the test box. Connect the electrometer to the
BNC output. Use the electrometer in normal mode for ohms
measurement.
Three-Terminal Connections-The GUARD output on the
Model 602 Electrometer can be used for resistance
measurements where the effects of cable capacitance may be
significant. Connect the unknown between INPUT and EXT
terminals. Connect the EXT terminal to the GUARD output
on the electrometer. Use the electrometer in fast mode for
ohms measurement.
I.E.4 Model 6105 Resistivity Chamber
The Model 6105 is a guarded test fixture for measurement of
surface and volume resistivities. The chamber is designed in
accordance with ASTM Standard Method of Test for Electri-
cal Resistance of Insulated Materials, D257-66. The Model
6105 can be used in conjunction with an electrometer and
voltage supply.
Resistivity can be determined by measuring the current
through a sample with a known voltage impressed. The
measurement can be made most conveniently when a set of
electrodes are used which can be calibrated in terms of
surface or volume resistivity. The Model 6105 has been
designed for use with a Keithley electrometer and an optional
high voltage supply such as the Model 247.
1.8.5 Model 2503 Static Detector Probe
Model 2503 is designed to detect voltage due to charge on
relatively small surface areas. Solid coaxial 13mm (% inch)
diameter tube used with 89mm (3% inch) head, 89mm (3%
inch) coupler, 25mm (one inch) adapter and two 90° angle
adapters which may be placed at various junctions along the
tube. It gives a 10,OOO:l & 10% divsion ratio when used with
Model 610C and held 6mm (‘/ inch) away from a charged
plane of at least 13mm (% inch) diameter. Output is a UHF
male plug.
I.E.8 Model 8011 Input Cable
The Model 6011 is a low-noise triaxial cable, 30 inches long,
terminated by three color-coded alligator clips. This cable
mates directly with the triaxial input. The cable is fabricated
using a Keithley connector (P/N CS-141) and low-noise cable
(P/N SC-22).
The Model 6011 may be used for measurements which re-
quire a triaxial connection, especially when the input LO is
floated above CASE ground.
I.E.7 Model 6012 Triax-to-Coax Adapter
The Model 6012 is an adapter for mating the triaxial input and
UHF (coax) type connectors. Permits using Models 220,602,
614, 616 and 619 with all Keithley electromete accessories
having UHF type connectors.
l-2