Keithley 2420 Service Manual

Model 2420 3A SourceMeter

Service Manual

®

A GREATER MEASURE OF CONFIDENCE

W ARRANTY

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 defecti ve.
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.

LIMIT A TION OF W ARRANTY

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-rechar geable
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 , INDIRECT, 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 T O ANY PERSON, OR DAMAGE T O PROPER TY.

Keithley Instruments, Inc.

Sales Offices: BELGIUM: Bergensesteenweg 709 • B-1600 Sint-Pieters-Leeuw • 02-363 00 40 • Fax: [phone]

CHINA: Y uan Chen Xin Building, Room 705 • 12 Yumin Road, Dewai, Madian • Beijing 100029 • 8610-6202-2886 • Fax: [phone]
FINLAND: Tietäjäntie 2 • 02130 Espoo • Phone: [phone] • Fax: [phone]
FRANCE: 3, allée des Garays • 91127 Palaiseau Cédex • 01-64 53 20 20 • Fax: [phone]
GERMANY: Landsberger Strasse 65 • 82110 Germering • 089/84 93 07-40 • Fax: [phone]
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INDIA: Flat 2B, Willocrissa • 14, Rest House Crescent • Bangalore 560 001 • 91-80-509-1320/21 • Fax: [phone]
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KOREA: FL., URI Building • 2-14 Yangjae-Dong • Seocho-Gu, Seoul 137-130 • 82-2-574-7778 • Fax: [phone]
NETHERLANDS: Postbus 559 • 4200 AN Gorinchem • 0183-635333 • Fax: [phone]
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SWITZERLAND: Kriesbachstrasse 4 • 8600 Dübendorf • 01-821 94 44 • Fax: [phone]
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28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: [phone]

1-888-KEITHLEY (534-8453) • www.keithley.com

© Copyright 2001 Keithley Instruments, Inc.

Printed in the U.S.A.

11/01

Model 2420 3A Sour ceMeter

Service Manual

®

©1997, Keithley Instruments, Inc.

All rights reserved.

Cleveland, Ohio, U.S.A.

Fifth Printing, October 2001

Document Number: 2420-902-01 Rev. E

Manual Print History

The print history shown below lists the printing dates of all Revisions and Addenda created
for this manual. The Revision Le vel letter increases alphabetically as the manual under goes sub­sequent updates. Addenda, which are released between Revisions, contain important change in­formation that the user should incorporate immediately into the manual. Addenda are numbered
sequentially . When a new Re vision is created, all Addenda associated with the previous Re vision
of the manual are incorporated into the new Revision of the manual. Each ne w Revision includes
a revised copy of this print history page.

Revision A (Document Number 2420-902-01)................................................................April 1997

Addendum A (Document Number 2420-902-02).............................................................April 1997

Revision B (Document Number 2420-902-01)..................................................................July 1998

Revision C (Document Number 2420-902-01)............................................................ January 1999

Revision D (Document Number 2420-902-01).................................................................June 2000

Revision E (Document Number 2420-902-01) ............................................................October 2001

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

S

afety 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 recognize shock hazards and are familiar with the safety precautions
required to avoid possible injury. Read and follow all installation, operation, and maintenance information carefully before us­ing the product. Refer to the manual for complete product specifications.

If the product is used in a manner not specified, the protection provided by the product may be impaired.
The types of product users are:

Responsible body

ment is operated within its specifications and operating limits, and for ensuring that operators are adequately trained.

Operators

instrument. They must be protected from electric shock and contact with hazardous live circuits.

Maintenance personnel

voltage or replacing consumable materials. Maintenance procedures are described in the manual. The procedures explicitly state
if the operator may perform them. Otherwise, they should be performed only by service personnel.

Service personnel

trained service personnel may perform installation and service procedures.
Keithley products are designed for use with electrical signals that are rated Installation Category I and Installation Category II,

as described in the International Electrotechnical Commission (IEC) Standard IEC 60664. Most measurement, control, and data
I/O signals are Installation Category I and must not be directly connected to mains voltage or to voltage sources with high tran­sient over-voltages. Installation Cate gory II connections require protection for high transient over -voltages often associated with
local A C mains connections. Assume all measurement, control, and data I/O connections are for connection to Category I sourc­es unless otherwise marked or described in the Manual.

Exercise extreme caution when a shock hazard is present. Lethal voltage may be present on cable connector jacks or test fixtures.
The American National Standards Institute (ANSI) states that a shock hazard exists when v oltage le vels greater than 30V RMS,

42.4V peak, or 60VDC are present.

circuit before measuring.

Operators of this product must be protected from electric shock at all times. The responsible body must ensure that operators
are prevented access and/or insulated from every connection point. In some cases, connections must be exposed to potential
human contact. Product operators 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,

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 limit fault current and voltage to the card.

Before operating an instrument, make sure the line cord is connected to a properly grounded power receptacle. Inspect the con­necting cables, test leads, and jumpers for possible wear, cracks, or breaks before each use.

When installing equipment where access to the main power cord is restricted, such as rack mounting, a separate main input pow­er disconnect device must be provided, in close proximity to the equipment and within easy reach of the operator.

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.

is the individual or group responsible for the use and maintenance of equipment, for ensuring that the equip-

use the product for its intended function. They must be trained in electrical safety procedures and proper use of the

perform routine procedures on the product to keep it operating properly, for example, setting the line

are trained to work on live circuits, and perform safe installations and repairs of products. Only properly

A good safety practice is to expect that hazardous voltage is present in any unknown

no conductive part of the circuit may be exposed.

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.

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 applied to the device under test. Safe operation requires the use

of a lid interlock.
If a screw is present, connect it to safety earth ground using the wire recommended in the user documentation.

!

The symbol on an instrument indicates that the user should refer to the operating instructions located in the manual.

The symbol on an instrument shows that it can source or measure 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

WARNING

information very carefully before performing the indicated procedure.

CAUTION

The
ranty.

Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and all test cables.
T o 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 an 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. Products that consist of a circuit board with
no case or chassis (e.g., data acquisition board for installation into a computer) should never require cleaning if handled accord­ing to instructions. If the board becomes contaminated and operation is affected, the board should be returned to the factory for
proper cleaning/servicing.

heading in a manual explains dangers that might result in personal injury or death. Al ways read the associated

heading in a manual explains hazards that could damage the instrument. Such damage may inv alidate the war -

11/01

T able of Contents

1

Performance Verification

Introduction.........................................................................................1-2

Verification test requirements ..............................................................1-2

Environmental conditions.............................................................1-2

Warm-up period............................................................................1-2

Line power....................................................................................1-3

Recommended test equipment .........................................................1-3

1Ω resistor characterization .........................................................1-3

Verification limits .............................................................................1-4

Example limits calculation............................................................1-4

Resistance limits calculation.........................................................1-4

Restoring factory defaults ................................................................1-5

Performing the verification procedures............................................1-5

Test summary................................................................................1-5

Test considerations .......................................................................1-6

Setting the source range and output value....................................1-6

Setting the measurement range.....................................................1-7

Compliance considerations ..............................................................1-7

Compliance limits.........................................................................1-7

Type of compliance.......................................................................1-7

Maximum compliance values.......................................................1-8

Determining compliance limit......................................................1-8

Taking the SourceMeter out of compliance..................................1-8

Output voltage accuracy...................................................................1-9

Voltage measurement accuracy...................................................1-10

Output current accuracy..............................................................1-11

Current measurement accuracy......................................................1-13

Resistance measurement accuracy .................................................1-15

Calibration

2

Introduction......................................................................................2-2

Environmental conditions.................................................................2-2

Temperature and relative humidity...............................................2-2

Warm-up period ............................................................................2-2

Line power....................................................................................2-2

Calibration considerations................................................................2-3

Calibration cycle...........................................................................2-3

Recommended calibration equipment...........................................2-3

1Ω resistor characterization..........................................................2-4

Unlocking calibration.......................................................................2-4

Unlocking calibration from the front panel..................................2-4

Unlocking calibration by remote..................................................2-5

Changing the password .......................................................................2-6

Changing the password from the front panel...............................2-6

Changing the password by remote...............................................2-6

Resetting the calibration password......................................................2-6

Viewing calibration dates and calibration count .................................2-7

Calibration errors.............................................................................2-7

Front panel error reporting ...........................................................2-7

Remote error reporting .................................................................2-7

Front panel calibration........................................................................2-7

Remote calibration ............................................................................2-14

Remote calibration commands...................................................2-14

Recommended calibration parameters.......................................2-15

Remote calibration procedure ....................................................2-17

Single-range calibration....................................................................2-22

Routine Maintenance

3

Introduction.........................................................................................3-2

Line fuse replacement .........................................................................3-2

T roubleshooting

4

Introduction.........................................................................................4-2

Repair considerations..........................................................................4-2

Power-on self-test................................................................................4-2

Front panel tests..................................................................................4-3

KEYS test.....................................................................................4-3

DISPLAY PATTERNS test ..........................................................4-3

CHAR SET test............................................................................4-4

Principles of operation ........................................................................4-4

Overall block diagram..................................................................4-4

Analog circuits .............................................................................4-4

Power supply................................................................................4-6

Output stage..................................................................................4-7

A/D converter...............................................................................4-8

Active guard.................................................................................4-8

Digital circuitry............................................................................4-8

Display board circuit theory.........................................................4-9

Troubleshooting................................................................................4-10

Display board checks .................................................................4-10

Power supply checks..................................................................4-11

Digital circuitry checks ..............................................................4-11

Analog circuitry checks..............................................................4-12

Battery replacement..........................................................................4-12

Battery replacement precautions................................................4-12

Battery replacement procedure...................................................4-13

No comm link error...........................................................................4-13

Disassembly

5

Introduction.........................................................................................5-2

Handling and cleaning.........................................................................5-2

Handling PC boards......................................................................5-2

Solder repairs................................................................................5-2

Static sensitive devices........................................................................5-3

Assembly drawings .............................................................................5-3

Case cover removal..............................................................................5-3

Analog board removal .........................................................................5-4

Digital board removal..........................................................................5-5

Front panel disassembly ......................................................................5-6

Removing power components..............................................................5-6

Power module removal.................................................................5-6

Instrument re-assembly........................................................................5-7

Replaceable Parts

6

Introduction..........................................................................................6-2

Parts lists..............................................................................................6-2

Ordering information...........................................................................6-2

Factory service.....................................................................................6-2

Component layouts..............................................................................6-2

A

Specifications

Accuracy calculations.......................................................................A-10

Measurement accuracy..............................................................A-10

Source accuracy........................................................................A-10

B

Command Reference

Introduction.........................................................................................B-2

Command summary............................................................................ B-2

Miscellaneous commands...................................................................B-3

Detecting calibration errors ................................................................ B-8

Reading the error queue............................................................... B-8

Error summary.............................................................................B-8

Status byte EAV (Error Available) bit.......................................... B-9

Generating an SRQ on error........................................................ B-9

Detecting calibration step completion.............................................. B-10

Using the *OPC? query............................................................. B-10

Using the *OPC command........................................................B-10

Generating an SRQ on calibration complete.............................B-11

C

Calibration Programs

Introduction........................................................................................ C-2

Computer hardware requirements...................................................... C-2

Software requirements........................................................................ C-2

Calibration equipment........................................................................ C-2

General program instructions............................................................. C-2

Program C-1 Model 2420 calibration program ........................... C-4

Requesting calibration constants........................................................ C-7

Program C-2 Requesting calibration constants ........................... C-7

List of Illustrations

1

Performance Verification

Connections for voltage verification tests....................................1-9

Connections for10µA to 1A range current verification tests .....1-11

Connections for 3A range current verification tests ..................1-12

Connections for resistance accuracy verification.......................1-15

2

Calibration

Voltage calibration test connections.............................................2-8

10µA to 1A range current calibration test connections..............2-10

3A range current calibration test connections............................2-12

Routine Maintenance

3

Rear panel ....................................................................................3-2

T roubleshooting

4

Overall block diagram..................................................................4-5

Analog circuitry block diagram...................................................4-5

Power supply block diagram........................................................4-6

Output state simplified schematic................................................4-7

Digital circuitry block diagram....................................................4-9

List of T ables

1

Performance Verification

Maximum compliance values...........................................................1-8

Output voltage accuracy limits.......................................................1-10

Voltage measurement accuracy limits ............................................1-11

Output current accuracy limits.......................................................1-13

Current measurement accuracy limits............................................1-14

Ohms measurement accuracy limits...............................................1-16

Calibration

2

Recommended calibration equipment............................................. 2-4

Calibration unlocked states ..............................................................2-5

Front panel voltage calibration.......................................................2-10

Front panel current calibration.......................................................2-13

Remote calibration command summary.........................................2-15

Recommended :CAL:PROT:SENS parameter ranges....................2-16

Recommended :CAL:PROT:SOUR parameter ranges...................2-16

Voltage calibration initialization commands ..................................2-18

Voltage range calibration commands .............................................2-19

Current calibration initialization commands..................................2-20

Current range calibration commands .............................................2-21

Recommended verification equipment ............................................1-3

Routine Maintenance

3

Power line fuse.................................................................................3-3

4

T roubleshooting

Display board checks .....................................................................4-10

Power supply checks......................................................................4-11

Digital circuitry checks ..................................................................4-11

Analog circuitry checks..................................................................4-12

6

Replaceable Parts

Analog board parts list .....................................................................6-3

Digital board parts list....................................................................6-12

Display board parts list...................................................................6-17

Mechanical parts list.......................................................................6-18

B

Command Reference

Remote calibration command summary ......................................... B-2

Recommended :CAL:PROT:SENS parameter ranges.................... B-6

Recommended :CAL:PROT:SOUR parameter ranges................... B-7

Calibration errors............................................................................ B-9

1

Performance

V erification

1-2 Performance Verification

Introduction

Use the procedures in this section to verify that Model 2420 accuracy is within the limits stated

in the instrument’s one-year accurac y specifications. You can perform these verification procedures:

• When you first receive the instrument to make sure that it was not damaged during shipment.

• To verify that the unit meets factory specifications.

• To determine if calibration is required.

• Following calibration to make sure it was performed properly.

WARNING

NOTE

The information in this section is intended for qualified service personnel
only. Do not attempt these procedures unless you are qualified to do so.
Some of these procedures may expose you to hazardous voltages, which
could cause personal injury or death if contacted. Use standard safety pre­cautions when working with hazardous voltages.

If the instrument is still under warranty and its performance is outside specified limits, con­tact your Keithle y r epr esentative or the factory to determine the correct course of action.

V erification test requirements

Be sure that you perform the verification tests:

• Under the proper environmental conditions.

• After the specified warm-up period.

• Using the correct line voltage.

• Using the proper test equipment.

• Using the specified output signals and reading limits.

Environmental conditions

Conduct your performance verification procedures in a test environment with:

• An ambient temperature of 18-28°C (65-82°F).

• A relative humidity of less than 70% unless otherwise noted.

W arm-up period

Allow the Model 2420 to warm up for at least one hour before conducting the verification

procedures.

If the instrument has been subjected to temperature extremes (those outside the ranges stated
above), allow additional time for the instrument’s internal temperature to stabilize. T ypically , al­low one extra hour to stabilize a unit that is 10°C (18°F) outside the specifi ed temperature range.

Also, allow the test equipment to warm up for the minimum time specified by the manuf acturer .

Line power

The Model 2420 requires a line voltage of 90 to 250V and a line frequency of 50 to 60Hz.

Verification tests must be performed within this range.

Recommended test equipment

T able 1-1 summarizes recommended verification equipment. You can use alternate equipment
as long as that equipment has specifications at least as good as those listed in Table 1-1. Keep in
mind, howev er, that test equipment uncertainty will add to the uncertainty of each measurement.
Generally, test equipment uncertainty should be at least four times better than corresponding Model
2420 specifications. Table 1-1 lists the specifications of the recommended test equipment, includ­ing maximum allowable uncertainty for alternate test equipment, which is shown in parentheses.

Table 1-1

Recommended verification equipment

Description Manufacturer/Model Specifications

Digital Multimeter Hewlett Packard

HP3458A

DC Voltage* 1V:

Performance Verification 1-3

±5.6ppm
10V:
100V:

±4.3ppm

±6.3ppm

µ

DC Current* 10

Resistance Calibrator Fluke 5450A Resistance** 1.9

Precision Resistor*** Isotec RUG-Z-1R00-0.1 1

* 90-day, full-range accuracy specifications of ranges required for various measurement points.
** 90-day, ±5°C specifications of nominal resistance values shown. Use actual values for tests. Maximum uncertainty of

alternate test equipment shown in parentheses.

*** Required for verification of 3A current range. Characterize resistor to ±300ppm or better using recommended DMM

before verifying 3A current measurement range.

A:

µ

100
1mA:
10mA:
100mA:
1A:

Ω

Ω

19

Ω

190

1.9k

Ω

19k
190k

1.9M
19M

Ω

, ±0.1%, 100W

±25ppm

A:

±23ppm

±20ppm

±20ppm

±35ppm

±110ppm

:

±65ppm (±460ppm)

:

±23ppm (±280ppm)

:

±10.5ppm (±230ppm)

Ω

:

±8ppm (±200ppm)

:

±7.5ppm (±195ppm)

Ω

:

±8.5ppm (±200ppm)

Ω

:

±11.5ppm (±180ppm)

Ω

:

±30ppm (±635ppm)

1-4 Performance Verification

1Ω resistor characterization

The recommended 1Ω resistor should be characterized to ±300ppm or better before verifying
the 3A current measurement range. (You need not characterize the resistor if you are checking
only the 3A current source range.) Use the 4-wire ohms function of the DMM recommended in
T able 1-1 to measure the resistance value, and then use that measured value to calculate the cur ­rent during the 3A current measurement range test procedure.

V erification limits

The verification limits stated in this section have been calculated using only the Model 2420
one-year accuracy specifications, and they do not include test equipment uncertainty. If a par­ticular measurement falls outside the allowable range, recalculate new limits based on Model
2420 specifications and corresponding test equipment specifications.

Example limits calculation

As an example of how verification limits are calculated, assume you are testing the 20V DC
output range using a 20V output value. Using the Model 2420 20V range one-year accuracy
specification of ±(0.02% of output + 2.4mV offset), the calculated output limits are:

Output limits = 20V ± [(20V

Output limits = 20V ± (0.004 + 0.0024)

Output limits = 20V ± 0.0064V

Output limits = 19.9936V to 20.0064V

Resistance limits calculation

When verifying the resistance measurement accuracy, it will probably be necessary to recal­culate resistance limits based on the actual calibrator resistance values. You can calculate resis­tance reading limits in the same manner described above, b ut be sure to use the actual calibrator
resistance values and the Model 2420 normal accuracy specifications for your calculations.

As an example, assume you are testing the 20k
inal 19k
accuracy specifications of ±(0.063% of reading + 3

Ω

calibrator resistor is 19.01kΩ. Using the Model 2420 20kΩ range one-year normal

Reading limits = 19.01k

Reading limits = 19.01k

Reading limits = 18.9950kΩ to 19.0250k

Ω
Ω

×

0.02%) + 2.4mV]

Ω

range, and that the actual value of the nom-

Ω

), the recalculated reading limits are:

± [(19.01kΩ × 0.063%) + 3Ω]
±15

Ω

Ω

Restoring factory defaults

Before performing the verification procedures, restore the instrument to its factory front panel

(bench) defaults as follows:

1. Press the MENU key. The instrument will display the following prompt:

MAIN MENU

SAVESETUP COMMUNICATION CAL

2. Select SAVESETUP, and then press ENTER. The unit then displays:

SAVESETUP MENU

GLOBAL SOURCE-MEMORY

3. Select GLOBAL, and then press ENTER. The unit then displays:

GLOBAL SETUP MENU

SAVE RESTORE POWERON RESET

4. Select RESET, and then press ENTER. The unit displays:

RESET ORIGINAL DFLTS

BENCH GPIB

5. Select BENCH, and then press ENTER. The unit then displays:

RESETTING INSTRUMENT

ENTER to confirm; EXIT to abort

6. Press ENTER to restore bench defaults, and note the unit displays the following:

RESET COMPLETE

BENCH defaults are now restored

Press ENTER to continue



7. Press ENTER then EXIT as necessary to return to normal display.

Performance Verification 1-5





Performing the verification test procedures

T est summary

• DC voltage output accuracy

• DC voltage measurement accuracy

• DC current output accuracy

• DC current measurement accuracy

• Resistance measurement accuracy

If the Model 2420 is not within specifications and not under warranty , see the calibration pro-

cedures in Section 2 for information on calibrating the unit.

1-6 Performance Verification

T est considerations

When performing the verification procedures:

• Be sure to restore factory front panel defaults as previously outlined.

• Make sure that the test equipment is properly warmed up and connected to the Model
2420 INPUT/OUTPUT jacks. Also be sure that the front panel jacks are selected with
the TERMINALS key.

• Make sure the Model 2420 is set to the correct source range (see below).

• Be sure that the Model 2420 output is turned on before making measurements.

• Be sure the test equipment is set up for the proper function and range.

• Allow the Model 2420 output signal to settle before making a measurement.

• Do not connect test equipment to the Model 2420 through a scanner, multiplexer, or
other switching equipment.

WARNING

CAUTION

The maximum common-mode voltage (voltage between LO and chassis
ground) is 250V peak. Exceeding this value may cause a breakdown in in­sulation, creating a shock hazard.

The maximum voltage between INPUT/OUTPUT HI and LO or 4-WIRE
SENSE HI and LO is 75V peak. The maximum voltage between INPUT/
OUTPUT HI and 4-WIRE SENSE HI or between INPUT/OUTPUT LO
and 4-WIRE SENSE LO is 5V. Exceeding these voltage values may result
in instrument damage.

Setting the source range and output value

Before testing each verification point, you must properly set the source range and output v al-

ue as outlined below.

1. Press either the SOURCE V or SOURCE I ke y to select the appropriate source function.

2. Press the EDIT key as required to select the source display field. Note that the cursor will
flash in the source field while its value is being edited.

3. With the cursor in the source display field flashing, set the source range to the lo west pos­sible range for the value to be sourced using the up or do wn RANGE ke y. For example,
you should use the 20V source range to output a 20V source value. With a 20V source
value and the 20V range selected, the source field display will appear as follows:

Vsrc:+20.0000 V

4. With the source field cursor flashing, set the source output to the required value using
either:

• The SOURCE adjustment and left and right arrow keys.

• The numeric keys.

5. Note that the source output value will be updated immediately; you need not press
ENTER when setting the source value.

Setting the measurement range

When simultaneously sourcing and measuring either voltage or current, the measure range is
coupled to the source range, and you cannot independently control the measure range. Thus, it
is not necessary for you to set the measure range when testing voltage or current measurement
accuracy.

Compliance considerations

Compliance limits

When sourcing voltage, you can set the SourceMeter to limit current from 10nA to 3.15A.
Conversely, when sourcing current, you can set the SourceMeter to limit voltage from 0.2mV to
63V. The SourceMeter output will not exceed the programmed compliance limit.

T ypes of compliance

There are two types of compliance that can occur: “real” and “range.” Depending on which
value is lower , the output will clamp at either the displayed compliance setting (“real”) or at the
maximum measurement range reading (“range”).

Performance Verification 1-7

The “real” compliance condition can occur when the compliance setting is less than the high­est possible reading of the measurement range. When in compliance, the source output clamps
at the displayed compliance value. For example, if the compliance voltage is set to 1V and the
measurement range is 2V, the output voltage will clamp (limit) at 1V.

“Range” compliance can occur when the compliance setting is higher than the possible read­ing of the selected measurement range. When in compliance, the source output clamps at the
maximum measurement range reading (not the compliance value). For example, if the compli­ance voltage is set to 1V and the measurement range is 200mV, the output voltage will clamp
(limit) at 210mV.

1-8 Performance Verification

Maximum compliance values

The maximum compliance values for the measurement ranges are summarized in Table 1-2.

Table 1-2

Maximum compliance values

Measurement
range

200mV
2V
20V
60V

10

µ

A

100

µ

A
1mA
10mA
100mA
1A
3A

When the SourceMeter goes into compliance, the “Cmpl” label or the units label (i.e., “mA”)

for the compliance display will flash.

Maximum
compliance value

210mV

2.1V
21V
63V

10.5

µ

A

105

µ

A

1.05mA

10.5mA
105mA

1.05A

3.15A

Determining compliance limit

The relationships to determine which compliance is in effect are summarized as follows.

They assume that the measurement function is the same as the compliance function.

• Compliance Setting < Measurement Range = Real Compliance

• Measurement Range < Compliance Setting = Range Compliance

You can determine the compliance that is in effect by comparing the displayed compliance
setting to the present measurement range. If the compliance setting is lower than the maximum
possible reading on the present measurement range, the compliance setting is the compliance
limit. If the compliance setting is higher than the measurement range, the maximum reading on
that measurement range is the compliance limit

T aking the SourceMeter out of compliance

Verification measurements should not be made when the SourceMeter is in compliance. For

purposes of the verification tests, the SourceMeter can be taken out of compliance by going into
the edit mode and increasing the compliance limit.

NOTE

Do not take the unit out of compliance by decreasing the sour ce value or changing the
range. Always use the recommended range and source settings when performing the
verification tests.

Output voltage accuracy

Follow the steps belo w to verify that Model 2420 output v oltage accurac y is within specified
limits. This test involves setting the output voltage to each full-range value and measuring the
voltages with a precision digital multimeter.

1. With the power of f, connect the digital multimeter to the Model 2420 INPUT/OUTPUT
jacks, as shown in Figure 1-1.

Figure 1-1

Connections for voltage
verification tests

Performance Verification 1-9

4- WIRE

INPUT/

SENSE

OUTPUT

HI

75V

75V

5V
PEAK

PEAK

PEAK



MEAS

EDIT

V

I

Ω

DISPLAY

1

LOCAL

67

DIGITS SPEED

230

REL

FILTER

89

STORE

TOGGLE

POWER

2420 3A SourceMeter

SOURCE

FCTN

I

V

4

EDIT

5

TRIG

SWEEP

LIMIT

+/-

EXIT ENTER

RECALL

CONFIG MENU

Model 2420

LO

250V
PEAK

RANGE
AUTO

TERMINALS

ON/OFF

FRONT/

RANGE

REAR

OUTPUT

Input HI

Input LO

Digital Multimeter

2. Select the multimeter DC volts measuring function.

3. Set the voltage source protection to NONE. To do so, press CONFIG then SOURCE V
to access the CONFIGURE V-SOURCE menu. Select PROTECTION, and set the volt­age source protection limit to NONE.

4. Press the Model 2420 SOURCE V key to source voltage, and make sure the source out­put is turned on.

5. Verify output voltage accuracy for each of the voltages listed in Table 1-3. For each test
point:

• Select the correct source range.

• Set the Model 2420 output voltage to the indicated value.

• Verify that the multimeter reading is within the limits given in the table.

6. Repeat the procedure for negative output voltages with the same magnitudes as those
listed in Table 1-3.

7. Repeat the entire procedure using the rear panel INPUT/OUTPUT jacks. Be sure to
select the rear panel jacks with the front panel TERMINALS key.

1-10 Performance Verification

Table 1-3

Output voltage accuracy limits

Model 2420

source range

200mV
2V
20V
60V

Model 2420 output

voltage setting

200.000mV

2.00000V

20.0000V

60.0000V

V oltage measurement accuracy

Follow the steps below to verify that Model 2420 voltage measurement accuracy is within
specified limits. The test inv olves setting the source v oltage to full-range values, as measured by
a precision digital multimeter, and then v erifying that the Model 2420 voltage readings are with­in required limits.

1. With the power of f, connect the digital multimeter to the Model 2420 INPUT/OUTPUT
jacks , as shown in Figure 1-1.

2. Select the multimeter DC volts function.

3. Set the voltage source protection to NONE. To do so, press CONFIG then SOURCE V
to access the CONFIGURE V-SOURCE menu. Select PROTECTION, and set the volt­age source protection limit to NONE.

4. Set the Model 2420 to both source and measure voltage by pressing the SOURCE V and
MEAS V keys, and make sure the source output is turned on.

5. Verify output voltage accuracy for each of the voltages listed in Table 1-4. For each test
point:

• Select the correct source range.

• Set the Model 2420 output voltage to the indicated value as measured by the digital
multimeter.

• Verify that the Model 2420 voltage reading is within the limits given in the table.

Output voltage limits

(1 year, 18°C-28°C)

199.360 to 200.640mV

1.99900 to 2.00100V

19.9936 to 20.0064V

59.9808 to 60.0192V

NOTE

It may not be possible to set the voltage sour ce to the specified value . Use the closest
possible setting, and modify reading limits accordingly.

6. Repeat the procedure for negative source voltages with the same magnitudes as those
listed in Table 1-4.

7. Repeat the entire procedure using the rear panel INPUT/OUTPUT jacks. Be sure to
select the rear panel jacks with the front panel TERMINALS key.

Table 1-4

Voltage measurement accuracy limits

Performance Verification 1-11

*Measure range coupled to source range when simultaneously sourcing and measuring voltage.
**As measured by precision digital multimeter. Use closest possible value, and modify reading limits

Output current accuracy

limits. The test involves setting the output current to each full-range value and measuring the
currents with a precision digital multimeter.

10µA to 1A range accuracy

Figure 1-2

Connections for 10
to 1A range current
verification tests

Model 2420 source

and measure range*

200mV
2V
20V
60V

Source voltage*

200.000mV

2.00000V

20.0000V

60.0000V

Model 2420 voltage reading

limits (1 year, 18°C-28°C)

199.676 to 200.324mV

1.99946 to 2.00054V

19.9960 to 20.0040V

59.9880 to 60.0120V

accordingly if necessary.

Follow the steps belo w to verify that Model 2420 output current accuracy is within specified

1. With the power of f, connect the digital multimeter to the Model 2420 INPUT/OUTPUT
jacks, as shown in Figure 1-2.

4- WIRE

INPUT/

SENSE

OUTPUT

HI

75V

75V

5V

PEAK

PEAK

µ

A

MEAS

EDIT

V

I

Ω

DISPLAY

1

LOCAL

67

DIGITS SPEED

230

REL

FILTER

89

STORE

TOGGLE

POWER

2420 3A SourceMeter

SOURCE

FCTN

I

V

4

5

EDIT

TRIG

SWEEP

LIMIT

+/-

EXIT ENTER

RECALL

CONFIG MENU

PEAK



LO

250V
PEAK

RANGE
AUTO

TERMINALS

ON/OFF

FRONT/

RANGE

REAR

OUTPUT

Model 2420

Input LO

Amps

Digital Multimeter

2. Select the multimeter DC current measuring function.

3. Press the Model 2420 SOURCE I key to source current, and make sure the source output
is turned on.

1-12 Performance Verification

4. Verify output current accuracy for the 10µA-1A range currents listed in Table 1-5. For
each test point:

• Select the correct source range.

• Set the Model 2420 output current to the correct value.

• Verify that the multimeter reading is within the limits given in the table.

5. Repeat the procedure for negative output currents with the same magnitudes as those
listed in Table 1-5.

6. Repeat the entire procedure using the rear panel INPUT/OUTPUT jacks. Be sure to
select the rear panel jacks with the front panel TERMINALS key.

3A range accuracy

1. With the power of f, connect the digital multimeter and the 1Ω resistor to the Model 2420
INPUT/OUTPUT jacks, as shown in Figure 1-3.

Figure 1-3

Connections for
3A range current
verification tests

4- WIRE

INPUT/

SENSE

OUTPUT

HI

75V

75V

5V

PEAK

PEAK

PEAK



V

4

TRIG

+/-

CONFIG MENU

2420 3A SourceMeter

SOURCE

I

5

EDIT

SWEEP

EXIT ENTER

MEAS

EDIT

DISPLAY

TOGGLE

POWER

V

LOCAL

67

DIGITS SPEED

FCTN

I

Ω

1

230

REL

LIMIT

FILTER

89

RECALL

STORE

LO

250V

RANGE
AUTO
RANGE

PEAK

TERMINALS

ON/OFF

FRONT/
REAR

OUTPUT

1Ω Resistor

Model 2420

Input HI

Input LO

Digital Multimeter

2. Select the multimeter DC volts measuring function.

3. Press the Model 2420 SOURCE I key to source current, and make sure the source output
is turned on.

4. Verify output current accuracy for the 3A range. Be sure to:

• Select the 3A source range.

• Set the Model 2420 output current to the correct 3A output value.

• Verify that the multimeter reading is within the 3A range limits given in Table 1-5.
(Since the value of the 1Ω resistor value is assumed to be the same as its nominal value,
the DMM voltage reading is the same as the sourced current.)

5. Repeat the procedure for a negative 3A current output value.

6. Repeat the entire procedure using the rear panel INPUT/OUTPUT jacks. Be sure to
select the rear panel jacks with the front panel TERMINALS key.

Table 1-5

Output current accuracy limits

Performance Verification 1-13

Model 2420

source range

10µA
100µA
1mA
10mA
100mA
1A
3A*

* See separate procedure for 3A range. DMM voltage reading is same as sourced current.

1

Specifications valid for continuous output currents below 105mA. For operating abov e 105mA on the 1A range

for >1 minute, derate accuracy 10%/100mA above 105mA. For operating abov e 105mA on the 3A range for >1
minute, derate accuracy 10%/300mA above 105mA.

Model 2420

output current setting

10.0000µA

100.000µA

1.00000mA

10.0000mA

100.000mA

1.00000A

3.00000A

Current measurement accuracy

Follow the steps below to verify that Model 2420 current measurement accuracy is within
specified limits. The procedure inv olves applying accurate currents from the Model 2420 current
source and then verifying that Model 2420 current measurements are within required limits.

10µA to 1A range accuracy

1. With the power of f, connect the digital multimeter to the Model 2420 INPUT/OUTPUT
jacks, as shown in Figure 1-2.

2. Select the multimeter DC current function.

3. Set the Model 2420 to both source and measure current by pressing the SOURCE I and
MEAS I keys, and make sure the source output is turned on.

4. V erify measure current accurac y for the 10µA-1A range currents listed in Table 1-6. For
each measurement:

• Select the correct source range.

• Set the Model 2420 source output to the correct value as measured by the digital multimeter .

• Verify that the Model 2420 current reading is within the limits given in the table.

Output current limits

(1 year, 18°C-28°C)

9.9947 to 10.0053µA

99.949 to 100.051µA

0.99946 to 1.00054mA

9.9935 to 10.0065mA

99.914 to 100.086mA

0.99843 to 1.00157A

2.99553 to 3.00447A

1
1

NOTE It may not be possible to set the current source to the specified value. Use the closest

possible setting, and modify reading limits accordingly.

5. Repeat the procedure for negative calibrator currents with the same magnitudes as those
listed in Table 1-6.

6. Repeat the entire procedure using the rear panel INPUT/OUTPUT jacks. Be sure to
select the rear panel jacks with the front panel TERMINALS key.

NOTE Test currents above 105mA cannot be maintained longer than 1 minute without

affecting accuracy. See derating information in Note 1 under Table 1-5.

1-14 Performance Verification

3A range accuracy

NOTE The 1Ω resistor should be characterized to within ±300ppm before verifying the 3A

current measur ement range. Use the 4-wir e ohms function of the DMM to measur e the
resistance value, and then use that measur ed value to calculate the curr ent during the
measurement procedure.

1. With the power off, connect the 1Ω resistor and digital multimeter to the Model 2420

INPUT/OUTPUT jacks, as shown in Figure 1-3.

2. Select the multimeter DC volts function.

3. Set the Model 2420 to both source and measure current by pressing the SOURCE I and
MEAS I keys, and make sure the source output is turned on.

4. Verify measurement current accuracy for the 3A range as follows:

• Select the 3A source range.

• Set the Model 2420 source output to the correct 3A value as measured by the digital

multimeter.

• Note the DMM voltage reading, and then calculate the current from the voltage reading

and characterized 1Ω resistance value as I = V/R, where V is the DMM voltage reading
and R is the characterized resistance value.

• V erify that the Model 2420 current reading is within the 3A limits gi ven in the Table 1-6.

NOTE It may not be possible to set the current sour ce to the specified 3A value . Use the clos-

est possible setting, and modify reading limits accordingly.

5. Repeat the procedure for a negative 3A current.

6. Repeat the procedure using the rear panel INPUT/OUTPUT jacks. Be sure to select the
rear panel jacks with the front panel TERMINALS key.

NOTE Test currents above 105mA cannot be maintained longer than 1 minute without

affecting accuracy. See derating information in Note 1 under Table 1-5.

Table 1-6

Current measurement accuracy limits

Model 2420 source

and measure range*

10µA
100µA
1mA
10mA
100mA
1A
3A

*Measure range coupled to source range when simultaneously sourcing and measuring current.
**As measured by precision digital multimeter. Use closest possible value, and modify reading limits

accordingly if necessary.

***Current calculated as follows: I = V/R, where V is the DMM voltage reading, and R is the character-

ized value of the 1Ω resistor.

Source current**

10.00000µA

100.000µA

1.00000mA

10.0000mA

100.000mA

1.00000A

3.00000A

Model 2420 current reading limits (1

year, 18°C-28°C)

9.9966 to 10.0034µA

99.969 to 100.031µA

0.99967 to 1.00033mA

9.9959 to 10.0041mA

99.939 to 100.061mA

0.99883 to 1.00117A

2.99673 to 3.00327A***

Resistance measurement accuracy

Use the following steps to verify that Model 2420 resistance measurement accuracy is
within specified limits. This procedure involves applying accurate resistances from a resis­tance calibrator and then verifying that Model 2420 resistance measurements are within re­quired limits.

CAUTION Before testing the 2Ω and 20Ω ranges make sure your resistance calibrator

can safely handle the default test currents for those ranges (see Model 2420
and calibrator specifications). If not, use the CONFIG OHMS menu to select
the MANUAL source mode, then set the source current to an appropriate safe
value. When using the manual source mode, total resistance reading uncer­tainty includes both Source I and Measure V uncertainty (see specifications),
and calculated reading limits should take the additional uncertainty into ac­count.

If using the Fluke 5450A resistance calibrator, you cannot use the Auto Ohms
mode of the Model 2420 to verify the 2Ω range. The 1A test current for the 2Ω
range of the Model 2420 will damage the calibrator. On the Model 2420, use
the CONFIG OHMS menu to select the MANUAL source mode, and then set
the source (test) current to 100mA.

Performance Verification 1-15

1. With the power off, connect the resistance calibrator to the Model 2420 INPUT/OUT-

Figure 1-4

Connections for resistance
accuracy verification

PUT and 4-WIRE SENSE jacks, as shown in Figure 1-4. Be sure to use the 4-wire con­nections as shown.

4- WIRE

INPUT/

SENSE

OUTPUT

HI

75V

75V

5V

PEAK

PEAK

PEAK



MEAS

EDIT

DISPLAY

TOGGLE

POWER

V

LOCAL

67

DIGITS SPEED

FCTN

I

Ω

V

1

230

4

TRIG

REL

LIMIT

FILTER

+/-

89

RECALL

STORE

CONFIG MENU

Model 2420

Resistance Calibrator

2420 3A SourceMeter

SOURCE

I

EDIT

5

SWEEP

EXIT ENTER

LO

RANGE
AUTO

ON/OFF

RANGE

OUTPUT

Output HI

Output LO

250V

PEAK

TERMINALS

FRONT/

REAR

Sense HI

Sense LO

1-16 Performance Verification

2. Select the resistance calibrator external sense mode.

3. Configure the Model 2420 ohms function for the 4-wire sense mode as follows:

• Press CONFIG then MEAS Ω. The instrument will display the following:

CONFIG OHMS

SOURCE SENSE-MODE GUARD

• Select SENSE-MODE, and then press ENTER. The following will be displayed:

SENSE-MODE

2-WIRE 4-WIRE

• Select 4-WIRE, and then press ENTER.

• Press EXIT to return to normal display.

4. Press MEAS Ω to select the ohms measurement function, and make sure the source out-

put is turned on.

5. Verify ohms measurement accuracy for each of the resistance v alues listed in Table 1-7.
For each measurement:

• Set the resistance calibrator output to the nominal resistance or closest av ailable value.

NOTE It may not be possible to set the resistance calibrator to the specified value. Use the

closest possible setting, and modify reading limits accordingly.

• Select the appropriate ohms measurement range with the RANGE keys.

• Verify that the Model 2420 resistance reading is within the limits given in the table.

6. Repeat the entire procedure using the rear panel INPUT/OUTPUT and 4-WIRE SENSE
jacks. Be sure to select the rear panel jacks with the front panel TERMINALS key.

Table 1-7

Ohms measurement accuracy limits

Model 2420 range Calibrator resistance*

2Ω
20Ω
200Ω
2kΩ
20kΩ
200kΩ
2MΩ
20MΩ

*Nominal resistance value.
**Reading limits based on Model 2420 normal accuracy specifications and nominal resistance values. If actual

resistance values differ from nominal values sho wn, recalculate reading limits using actual calibrator resistance
values and Model 2420 normal accuracy specifications. See Verification limits earlier in this section for details.

1.9Ω
19Ω
190Ω

1.9kΩ
19kΩ
190kΩ

1.9MΩ
19MΩ

Model 2420 resistance reading limits**

(1 year, 18°C-28°C)

1.89649 to 1.90351Ω

18.9784 to 19.0216Ω

189.824 to 190.176Ω

1.89845 to 1.90155kΩ

18.9850 to 19.0150kΩ

189.847 to 190.153kΩ

1.89861 to 1.90139MΩ

18.9517 to 19.0483MΩ

2

Calibration

2-2 Calibration

Introduction

Use the procedures in this section to calibrate the Model 2420. These procedures require
accurate test equipment to measure precise DC voltages and currents. Calibration can be performed
either from the front panel or by sending SCPI calibration commands over the
IEEE-488 bus or RS-232 port with the aid of a computer.

WARNING

This information in this section is intended for qualified service personnel
only. Do not attempt these procedures unless you are qualified to do so.
Some of these procedures may expose you to hazardous voltages.

Environmental conditions

T emperature and relative humidity

Conduct the calibration procedures at an ambient temperature of 18-28°C (65-82°F) with rel­ative humidity of less than 70% unless otherwise noted.

W arm-up period

Allow the Model 2420 to warm up for at least one hour before performing calibration.

If the instrument has been subjected to temperature extremes (those outside the ranges stated
above), allow additional time for the instrument’s internal temperature to stabilize. Typically,
allow one extra hour to stabilize a unit that is 10°C (18°F) outside the specified temperature
range.

Also, allow the test equipment to warm up for the minimum time specified by the manuf acturer .

Line power

The Model 2420 requires a line voltage of 90 to 250V at line frequency of 50 to 60Hz. The
instrument must be calibrated while operating from a line voltage within this range.

Calibration considerations

When performing the calibration procedures:

• Make sure that the test equipment is properly warmed up and connected to the Model
2420 front panel INPUT/OUTPUT jacks. Also be certain that the front panel jacks are
selected with the TERMINALS switch.

• Always allow the source signal to settle before calibrating each point.

• Do not connect test equipment to the Model 2420 through a scanner or other switching
equipment.

• If an error occurs during calibration, the Model 2420 will generate an appropriate error
message. See Appendix B for more information.

Calibration 2-3

WARNING

CAUTION

The maximum common-mode voltage (voltage between LO and chassis
ground) is 250V peak. Exceeding this value may cause a breakdown in in­sulation, creating a shock hazard.

The maximum voltage between INPUT/OUTPUT HI and LO or 4-WIRE
SENSE HI and LO is 75V peak. The maximum voltage between INPUT/
OUTPUT HI and 4-WIRE SENSE HI or between INPUT/OUTPUT LO
and 4-WIRE SENSE LO is 5V. Exceeding these voltage values may result
in instrument damage.

Calibration cycle

Perform calibration at least once a year to ensure the unit meets or exceeds its specifications.

Recommended calibration equipment

Table 2-1 lists the recommended equipment for the calibration procedures. You can use al­ternate equipment as long that equipment has specifications at least as good as those listed in the
table. For optimum calibration accuracy, test equipment specifications should be at least four
times better than corresponding Model 2420 specifications.

2-4 Calibration

Table 2-1

Recommended calibration equipment

Description Manufacturer/Model Specifications

Digital Multimeter Hewlett Packard

HP3458A

Precision Resistor** Isotec RUG-Z-1R00-0.1 1

*90-day, full-range accuracy specifications of ranges required for various measurement points.

** Necessary for calibration of 3A current range. Resistor must be characterized to ±300ppm or better using recom-

mended DMM before calibrating 3A range.

DC Voltage*

DC Current*

1V:
10V:
100V

µ

A:

10

µ

A:

100
1mA:
10mA:
100mA:
1A:

Ω

, ±0.1%, 100W

±5.6ppm

±4.3ppm
±6.3ppm

±25ppm
±23ppm
±20ppm
±20ppm
±35ppm

±110ppm

1Ω resistor characterization

The 1Ω resistor must be characterized to ±300ppm or better before calibrating the 3A current
range. Use the 4-wire ohms function of the DMM recommended in Table 1-1 to measure the re­sistance value, and then use that measured value to calculate the current during the 3A current
range calibration procedure.

Unlocking calibration

Before performing calibration, you must first unlock calibration by entering or sending the
calibration password as explained in the following paragraphs.

Unlocking calibration from the front panel

1. Press the MENU key , and then choose CAL, and press ENTER. The instrument will dis­play the following:

CALIBRATION

UNLOCK EXECUTE VIEW-DATES



SAVE LOCK CHANGE-PASSWORD

2. Select UNLOCK, and then press ENTER. The instrument will display the following:

PASSWORD:

Use ,,,, ENTER or EXIT.

3. Use the up and down RANGE keys to select the letter or number, and use the left and
right arrow keys to choose the position. (Press do wn RANGE for letters; up RANGE for
numbers.) Enter the present password on the display. (Front panel default: 002420.)

Calibration 2-5

4. Once the correct password is displayed, press the ENTER key. If the password was cor­rectly entered, the following message will be displayed:

CALIBRATION UNLOCKED

Calibration can now be executed.

5. Press EXIT to return to normal display. Calibration will be unlocked and assume the
states summarized in T able 2-2. Attempts to change any of the settings listed below with
calibration unlocked will result in an error +510, "Not permitted with cal un-locked."

NOTE

With calibr ation unlock ed, the sense function and rang e trac k the sour ce function and
range. That is, when :SOUR:FUNC is set to VOLT, the :SENS:FUNC setting will be
'VOLT:DC'. When :SOUR:FUNC is set to CURR, the :SENS:FUNC setting will be
'CURR:DC'. A similar command coupling exists for :SOUR:V OL T :RANG/
:SENS:VOLT:RANG and SOUR:CURR:RANG:SENS:CURR:RANG.

Table 2-2

Calibration unlocked states

Mode State Equivalent remote command

Concurrent Functions
Sense Function
Sense Volts NPLC
Sense Volts Range
Sense Current NPLC
Sense Current Range
Filter Count
Filter Control
Filter A veraging
Source V Mode
Volts Autorange
Source I Mode
Current Autorange
Autozero
Trigger Arm Count
Trigger Arm Source
Trigger Count
Trigger Source

OFF
Source

1.0
Source V

1.0
Source I
10
REPEAT
ON
FIXED
OFF
FIXED
OFF
ON
1
Immediate
1
Immediate

:SENS:FUNC:CONC OFF
:SENS:FUNC <source_ function>
:SENS:VOLT:NPLC 1.0
:SENS:VOLT:RANG <source_V_range>
:SENS:CURR:NPLC 1.0
:SENS:CURR:RANG <source_ I_ range>
:SENS:AVER:COUN 10
:SENS:AVER:TCON REPeat
:SENS:AVER:STAT ON
:SOUR:VOLT:MODE FIXED
:SOUR:VOLT:RANG:AUTO OFF
:SOUR:CURR:MODE FIXED
:SOUR:CURR:RANG:AUTO OFF
:SYST:AZERO ON
:ARM:COUNT 1
:ARM:SOUR IMMediate
:TRIG:COUNT 1
:TRIG:SOUR IMMediate

Unlocking calibration by remote

To unlock calibration via remote, send the following command:

:CAL:PROT:CODE '<password>'

For example, the following command uses the default password:

:CAL:PROT:CODE 'KI002420'

2-6 Calibration

Changing the password

The default password may be changed from the front panel or via remote as discussed belo w.

Changing the password from the front panel

Follow the steps below to change the password from the front panel:

1. Press the MENU key, then choose CAL and press ENTER. The instrument will display
the following:

CALIBRATION

UNLOCK EXECUTE VIEW-DATES

SAVE LOCK CHANGE-PASSWORD



2. Select UNLOCK, then enter the password. (Default: 002420.)

3. Select CHANGE-P ASSWORD, and then press ENTER. The instrument will display the
following:

New Pwd: 002420

Use , , , , ENTER or EXIT.

4. Using the range keys, and the left and right arrow keys, enter the new password on the
display.

5. Once the desired password is displayed, press the ENTER key to store the ne w password.



Changing the password by remote

T o change the calibration password by remote, first send the present passw ord, and then send
the new password. For example, the following command sequence changes the password from
the 'KI002420' remote default to 'KI_CAL':

:CAL:PROT:CODE 'KI002420'

:CAL:PROT:CODE 'KI_CAL'

You can use any combination of letters and numbers up to a maximum of eight characters.

NOTE

If you change the first two characters of the password to something other than
"KI", you will not be able to unlock calibration from the front panel.

Resetting the calibration password

If you lose the calibration password, you can unlock calibration by shorting together the CAL
pads, which are located on the display board. Doing so will also reset the password to the factory
default (KI002420).

See Section 5 for details on disassembling the unit to access the CAL pads. Refer to the dis­play board component layout drawing at the end of Section 6 for the location of the CAL pads.

Calibration 2-7

V iewing calibration dates and calibration count

When calibration is locked, only the UNLOCK and VIEW-DATES selections will be acces-

sible in the calibration menu. To view calibration dates and calibration count at any time:

1. From normal display, press MENU, select CAL, and then press ENTER. The unit will
display the following:

CALIBRATION

UNLOCK EXECUTE VIEW-DATES

2. Select VIEW -D ATES, and then press ENTER. The Model 2420 will display the next and
last calibration dates and the calibration count as in the following example:

NEXT CAL: 02/15/98

Last calibration: 02/15/97 Count: 0001

Calibration errors

The Model 2420 checks for errors after each calibration step, minimizing the possibility that

improper calibration may occur due to operator error.

Front panel error reporting

If an error is detected during comprehensive calibration, the instrument will display an appro­priate error message (see Appendix B). The unit will then prompt you to repeat the calibration
step that caused the error.

Remote error reporting

You can detect errors while in remote by testing the state of EAV (Error A vailable) bit (bit 2)
in the status byte. (Use the *STB? query to request the status byte.) Query the instrument for the
type of error by using the appropriate :SYST:ERR? query. The Model 2420 will respond with the
error number and a text message describing the nature of the error. See Appendix B for details.

Front panel calibration

The front panel calibration procedure described below calibrates all ranges of both the current
and voltage source and measure functions. Note that each range is separately calibrated by re­peating the entire procedure for each range.

Step 1: Prepare the Model 2420 for calibration

1. Turn on the Model 2420 and the digital multimeter, and allow them to warm up for at
least one hour before performing calibration.

2-8 Calibration

2. Press the MENU key, then choose CAL and press ENTER. Select UNLOCK, and then
press ENTER. The instrument will display the following:

PASSWORD:

Use , , , , ENTER or EXIT.

3. Use the up and down range keys to select the letter or number, and use the left and right
arrow keys to choose the position. Enter the present password on the display. (Front
panel default: 002420.) Press ENTER to complete the process.

4. Press EXIT to return to normal display. Instrument operating states will be set as sum­marized in Table 2-2.

Step 2: Voltage calibration

Perform the steps below for each voltage range, using Table 2-3 as a guide.

1. Connect the Model 2420 to the digital multimeter, as shown in Figure 2-1. Select the
multimeter DC volts measurement function.

NOTE

Figure 2-1

Voltage calibration
test connections

The 2-wire connections shown assume that remote sensing is not used. Remote
sensing may be used, if desired, b ut it is not essential when using the r ecommend­ed digital multimeter.

4- WIRE

INPUT/

SENSE

OUTPUT

HI

75V

75V

5V

PEAK

PEAK

PEAK



2420 3A SourceMeter

LO

MEAS

EDIT

V

DISPLAY

TOGGLE

LOCAL

POWER

67

DIGITS SPEED

SOURCE

FCTN

I

I

Ω

V

1

230

4

5

EDIT

TRIG

REL

SWEEP

LIMIT

FILTER

+/-

89

EXIT ENTER

RECALL

STORE

CONFIG MENU

250V
PEAK

RANGE

AUTO

TERMINALS

ON/OFF

FRONT/

RANGE

REAR

OUTPUT

Model 2420

Input HI

Input LO

Digital Multimeter

2. From normal display, press the SOURCE V key.

3. Press the EDIT key to select the source field (cursor flashing in source display field), and
then use the down RANGE key to select the 200mV source range.

4. From normal display, press MENU.

5. Select CAL, and then press ENTER. The unit will display the following:

CALIBRATION

UNLOCK EXECUTE VIEW-DATES

SAVE LOCK CHANGE-PASSWORD





6. Select EXECUTE, and then press ENTER. The instrument will display the following message:

V-CAL

Press ENTER to Output +200.00mV

Calibration 2-9

7. Press ENTER. The Model 2420 will source +200mV and simultaneously display the fol­lowing:

DMM RDG: +200.0000mV

Use , , , ,

ENTER, or EXIT.

8. Note and record the DMM reading, and then adjust the Model 2420 display to agree
exactly with the actual DMM reading. Use the up and down arro w keys to select the digit
value, and use the left and right arrow k eys to choose the digit position (or use the num­ber keys, 0-9, +/-). Note that the display adjustment range is within ±10% of the present
range.

9. After adjusting the display to agree with the DMM reading, press ENTER. The instru­ment will then display the following:

V-CAL
Press ENTER to Output +000.00mV

10. Press ENTER. The Model 2420 will source 0mV and at the same time display the following:

DMM RDG: +000.0000mV

Use , , , ,ENTER, or EXIT.

11. Note and record the DMM reading, and then adjust the Model 2420 display to agree with
the actual DMM reading. Note that the display value adjustment limits are within ±1%
of the present range.

12. After adjusting the display value to agree with the DMM reading, press ENTER. The
unit will then display the following:

V-CAL

Press ENTER to Output -200.00mV

13. Press ENTER. The Model 2420 will source -200mV and display the following:

DMM RDG: -200.0000mV

Use , , , , ENTER, or EXIT.

14. Note and record the DMM reading, and then adjust the Model 2420 display to agree with the
DMM reading. Again, the maximum display adjustment is within ± 10% of the present
range.

15. After adjusting the display value to agree with the DMM reading, press ENTER and note
that the instrument displays:

V-CAL

Press ENTER to Output -000.00mV

16. Press ENTER The Model 2420 will source -0mV and simultaneously display the following:

DMM RDG: +000.0000mV

Use , , , , ENTER or EXIT.

17. Note and record the DMM reading, and then adjust the display to agree with the DMM
reading. Once again, the maximum adjustment is within ±1% of the present range.

18. After adjusting the display to agree with the DMM reading, press ENTER to complete
calibration of the present range.

19. Press EXIT to return to normal display, and then select the 2V source range. Repeat steps
2 through 18 for the 2V range.

20. After calibrating the 2V range, repeat the entire procedure for the 20V and 60V ranges
using Table 2-3 as a guide. Be sure to select the appropriate source range with the EDIT
and RANGE keys before calibrating each range.

21. Press EXIT as necessary to return to normal display.

2-10 Calibration

Table 2-3

Front panel voltage calibration

Source
range*

Source voltage

0.2V +200.00mV
+000.00mV

-200.00mV

-000.00mV

2V +2.0000V

+0.0000V

-2.0000V

-0.0000V

20V +20.000V

+00.000V

-20.000V

-00.000V

60V +60.000V

+00.000V

-60.000V

-00.000V

Multimeter voltage

reading**

___________ mV
___________ mV
___________ mV
___________ mV

___________ V
___________ V
___________ V
___________ V

___________ V
___________ V
___________ V
___________ V

___________ V
___________ V
___________ V
___________ V

*Use EDIT and RANGE keys to select source range.
**Multimeter reading used in corresponding calibration step. See procedure.

Step 3: Current calibration

Perform the steps below for each current range, using Table 2-4 as a guide.

1. Connect the Model 2420 to the digital multimeter, as shown in Figure 2-2. Select the
multimeter DC current measurement function.

Figure 2-2

µ

A to 1A range current

10
calibration test connections

MEAS

EDIT

V

I

Ω

DISPLAY

1

230

TOGGLE

LOCAL

REL

FILTER

POWER

67

89

DIGITS SPEED

STORE

Model 2420

Digital Multimeter

4- WIRE

INPUT/

SENSE

OUTPUT

HI

75V

75V

5V
PEAK

PEAK

PEAK



2420 3A SourceMeter

LO

SOURCE

FCTN

I

V

4

5

EDIT

TRIG

SWEEP

LIMIT

+/-

EXIT ENTER

RECALL

CONFIG MENU

250V
PEAK

RANGE

AUTO

TERMINALS

ON/OFF

FRONT/

RANGE

REAR

OUTPUT

Input LO

Amps

Calibration 2-11

2. From normal display, press the SOURCE I key.

3. Press the EDIT key to select the source display field, and then use the down RANGE k ey

to select the 10µA source range.

4. From normal display, press MENU.

5. Select CAL, and then press ENTER. The unit will display the following:

CALIBRATION

UNLOCK EXECUTE VIEW-DATES 
 SAVE LOCK CHANGE-PASSWORD

6. Select EXECUTE, and then press ENTER. The instrument will display the following message:

I-CAL

Press ENTER to Output +10.000µA

7. Press ENTER. The Model 2420 will source +10µA and simultaneously display the fol-

lowing:

DMM RDG: +10.00000µA
Use

, , , , ENTER, or EXIT.

8. Note and record the DMM reading, and then adjust the Model 2420 display to agree
exactly with the actual DMM reading. Use the up and down arro w k eys to select the digit
value, and use the left and right arrow k eys to choose the digit position (or use the number
keys, 0-9, +/-). Note that the display adjustment range is within ±10% of the present range.

9. After adjusting the display to agree with the DMM reading, press ENTER. The instru­ment will then display the following:

I-CAL

Press ENTER to Output +00.000µA

10. Press ENTER. The Model 2420 will source 0mA and at the same time display the following:

DMM RDG: +00.00000µA

Use , , , , ENTER, or EXIT.

11. Note and record the DMM reading, and then adjust the Model 2420 display to agree with
the actual DMM reading. Note that the display value adjustment limits are within ±1%
of the present range.

12. After adjusting the display value to agree with the DMM reading, press ENTER. The
unit will then display the following:

I-CAL

Press ENTER to Output -10.000µA

13. Press ENTER. The Model 2420 will source -10µA and display the following:

DMM RDG: -10.00000µA

Use , , , , ENTER, or EXIT.

14. Note and record the DMM reading, and then adjust the Model 2420 display to agree with
the DMM reading. Again, the maximum display adjustment is within ± 10% of the
present range.

15. After adjusting the display value to agree with the DMM reading, press ENTER and note
that the instrument displays:

I-CAL

Press ENTER to Output -00.000µA

2-12 Calibration

16. Press ENTER The Model 2420 will source -0µA and simultaneously display the follo wing:

DMM RDG: +00.00000µA

Use , , , , ENTER, or EXIT.

17. Note and record the DMM reading, and then adjust the display to agree with the DMM
reading. Once again, the maximum adjustment is within ±1% of the present range.

18. After adjusting the display to agree with the DMM reading, press ENTER to complete
calibration of the present range.

19. Press EXIT to return to normal display , and then select the 100µA source range use the
EDIT and up RANGE keys. Repeat steps 2 through 18 for the 100µA range.

20. After calibrating the 100µA range, repeat the entire procedure for the 1mA through 1A
ranges using T able 2-4 as a guide. Be sure to select the appropriate source range with the
EDIT and up RANGE keys before calibrating each range.

21. After calibrating the 1A range, connect the 1Ω characterized resistor and DMM to the
Model 2420 INPUT/OUTPUT jacks, as shown in Figure 2-3.

22. Select the DMM DC volts function.

23. Repeat steps 2 through 18 for the 3A range using Table 2-4 as a guide. When entering
the DMM reading, use the calculated current as follows: I = V/R, where V is the DMM
voltage reading, and R is the characterized value of the 1Ω resistor.

Figure 2-3

3A range current
calibration test
connections

MEAS

EDIT

DISPLAY

TOGGLE

POWER

V

LOCAL

67

DIGITS SPEED

FCTN

I

Ω

1

230

REL

LIMIT

FILTER

89

RECALL

STORE

Model 2420

Digital Multimeter

V

4

TRIG

+/-

CONFIG MENU

4- WIRE

INPUT/

SENSE

OUTPUT

HI

75V

75V

5V

PEAK

PEAK

PEAK



2420 3A SourceMeter

SOURCE

I

5

EDIT

SWEEP

EXIT ENTER

LO

250V

RANGE

AUTO

RANGE

PEAK

TERMINALS

ON/OFF

FRONT/

REAR

OUTPUT

1Ω Resistor

Input HI

Input LO

Table 2-4

Front panel current calibration

Source range* Source current

10µA +10.000µA

+00.000µA

-10.000µA

-00.000µA

100µA +100.00µA

+000.00µA

-100.00µA

-000.00µA

1mA +1.0000mA

+0.0000mA

-1.0000mA

-0.0000mA

10mA +10.000mA

+00.000mA

-10.000mA

-00.000mA

100mA +100.00mA

+000.00mA

-100.00mA

-000.00mA

1A +1.0000A

+0.0000A

-1.0000A

-0.0000A

3A*** +3.0000A

+0.0000A

-3.0000A

-0.0000A

*Use EDIT and RANGE keys to select source range.
**Multimeter reading used in corresponding calibration step. See procedure.
***Current calculated as follows: I = V/R, where V is the DMM reading, and R is the

characterized value of the 1Ω resistor.

Multimeter
current reading**

___________ µA
___________ µA
___________ µA
___________ µA

___________ µA
___________ µA
___________ µA
___________ µA

___________ mA
___________ mA
___________ mA
___________ mA

___________ mA
___________ mA
___________ mA
___________ mA

___________ mA
___________ mA
___________ mA
___________ mA

___________ A
___________ A
___________ A
___________ A

___________ A
___________ A
___________ A
___________ A

Calibration 2-13

Step 4: Enter calibration dates and save calibration

NOTE For temporary calibration without saving new calibration constants, proceed to

Step 5: Lock out calibration.

1. From normal display, press MENU.

2. Select CAL, and then press ENTER. The Model 2420 will display the following:

CALIBRATION

UNLOCK EXECUTE VIEW-DATES 
 SAVE LOCK CHANGE-PASSWORD

2-14 Calibration

3. Select SAVE, and then press ENTER. The instrument will display the following message:

SAVE CAL
Press ENTER to continue; EXIT to abort calibration sequence.

4. Press ENTER. The unit will prompt you for the calibration date:

CAL DATE: 2/15/97

Use , , , , ENTER, or EXIT.

5. Change the displayed date to today's date, and then press the ENTER key . Press ENTER
again to confirm the date.

6. The unit will then prompt for the calibration due date:

NEXT CAL: 2/15/98

Use , , , , ENTER, or EXIT.

7. Set the calibration due date to the desired value, and then press ENTER. Press ENTER
again to confirm the date.

8. Once the calibration dates are entered, calibration is complete, and the following mes­sage will be displayed:

CALIBRATION COMPLETE

Press ENTER to confirm; EXIT to abort

9. Press ENTER to save the calibration data (or press EXIT to abort without saving cali­bration data.) The following message will be displayed:

CALIBRATION SUCCESS

Press ENTER or EXIT to continue.

10. Press ENTER or EXIT to complete process.

Step 5: Lock out calibration

1. From normal display, press MENU.

2. Select CAL, and then press ENTER. The Model 2420 will display the following:

CALIBRATION

UNLOCK EXECUTE VIEW-DATES 
 SAVE LOCK CHANGE-PASSWORD

3. Select LOCK, and then press ENTER. The instrument will display the following message:

CALIBRATION LOCKED.

Press ENTER or EXIT to continue.

4. Press ENTER or EXIT to return to normal display.

Remote calibration

Use the following procedure to perform remote calibration by sending SCPI commands o ver
the IEEE-488 bus or RS-232 port. The remote commands and appropriate parameters are sepa­rately summarized for each step.

Remote calibration commands

Table 2-5 summarizes remote calibration commands. For a more complete description of

these commands, refer to Appendix B.

Table 2-5

Remote calibration command summary

Command Description

Calibration 2-15

:CALibration

:PROTected

:CODE '<password>'
:COUNT?

:SAVE
:LOCK
:LOCK?
:DATE <y>,<m>,<d>
:DATE?
:NDUE <y>,<m>,<d>
:NDUE?
:SENSe <nrf>

:DATA?

:SOURce <nrf>

:DATA?

* Calibration data will not be saved if:

1. Calibration was not unlocked with :CODE command.

2. Invalid data exists. (For example, cal step failed or was aborted.)

3. Incomplete number of cal steps were performed. ( For example, omitting a negative full-scale step).
Ranges that calibrated successfully will be saved if calibration is unlocked. Ranges that failed will not be saved.

Calibration subsystem.
Cal commands protected by password.
Unlock cal; changes password if cal is already unlocked.
(Default password: KI002420.)
Query number of times 2420 has been calibrated.
Save calibration data to EEPROM.*
Lock calibration, inhibit SAVE command operation.
Request cal lock status.
Program calibration year, month, day.
Query calibration year, month, day.
Program calibration due year, month, day.
Query calibration due year, month, day.
Calibrate active measure range. (See Table 2-6 parameters.)
Query measurement cal constants for active range.
Calibrate active source range. (See Table 2-7 parameters.)
Query source cal constants for active range.

Recommended calibration parameters

The maximum calibration command parameter ranges are: 75% to 150% of full scale for pos­itive and negative full scale calibration points; ± zero calibration steps have ±50% of full scale
for valid entry ranges. However, for optimum calibration, it is recommended that you use cali­bration points within the ranges listed in Table 2-6 and Table 2-7. Note that each sense range
requires three parameters: zero, negativ e full scale, and positive full scale. Similarly , each source
range requires four parameters: two zero parameters, a positive full-scale parameter, and a neg­ative full-scale parameter.

2-16 Calibration

Table 2-6

Recommended :CALibration:PROTected:SENse parameter ranges

Sense
range

First parameter
(zero)

Second parameter
(negative full scale)

Third parameter
(positive full scale)

0.2V -0.002 to +0.002 -0.18 to -0.22 +0.18 to +0.22
2V -0.02 to +0.02 -1.8 to -2.2 +1.8 to +2.2
20V -0.2 to +0.2 -18 to -22 +18 to +22
60V -0.5 to +0.5 -50 to -65 +50 to +65

10µA -1E-7 to +1E-7 -9E-6 to -11E-6 +9E-6 to +11E-6
100µA -1E-6 to +1E-6 -90E-6 to -110E-6 +90E-6 to +110E-6
1mA -1E-5 to +1E-5 -0.9E-3 to -1.1E-3 +0.9E-3 to +1.1E-3
10mA -1E-4 to +1E-4 -9E-3 to -11E-3 +9E-3 to +11E-3
100mA -1E-3 to +1E-3 -90E-3 to -110E-3 +90E-3 to +110E-3
1A -1E-2 to +1E-2 -0.9 to -1.1 +0.9 to +1.1
3A -3E-2 to +3E-2 -2.7 to -3.15 +2.7 to +3.15

Note: Parameter steps for each range may be performed in any order, but all three parameter steps for each
range must be completed. For optimum calibration, use parameters within recommended limits.

Table 2-7

Recommended :CALibration:PROTected:SOURce parameter ranges

Fourth
parameter
(positive zero)

Source range

Second parameter
(negative full scale)

Second parameter
(negative zero)

Third parameter
(positive full scale)

0.2V -0.18 to -0.22 -0.002 to +0.002 +0.18 to +0.22 -0.002 to +0.002
2V -1.8 to -2.2 -0.02 to +0.02 +1.8 to +2.2 -0.02 to +0.02
20V -18 to -22 -0.2 to +0.2 +18 to +22 -0.2 to +0.2
60V -50 to -65 -0.5 to +0.5 +50 to +65 -0.5 to +0.5

10µA -9E-6 to -11E-6 -1E-7 to +1E-7 +9E-6 to +11E-6 -1E-7 to +1E-7
100µA -90E-6 to -110E-6 -1E-6 to +1E-6 +90E-6 to +110E-6 -1E-6 to +1E-6
1mA -0.9E-3 to -1.1E-3 -1E-5 to +1E-5 +0.9E-3 to +1.1E-3 -1E-5 to +1E-5
10mA -9E-3 to -1E-3 -1E-4 to +1E-4 +9E-3 to +11E-3 -1E-4 to +1E-4
100mA -90E-3 to -110E-3 -1E-3 to +1E-3 +90E-3 to +110E-3 -1E-3 to +1E-3
1A -0.9 to -1.1 -1E-2 to +1E-2 +0.9 to +1.1 -1E-2 to +1E-2
3A -2.7 to -3.15 -3E-2 to +3E-2 +2.7 to +3.15 -3E-2 to +3E-2

Note: Parameter steps for each range may be performed in any order, b ut all four parameter steps for each range
must be completed. For optimum calibration, use parameters within recommended limits.

Remote calibration procedure

Step 1: Prepare the Model 2420 for calibration

1. Connect the Model 2420 to the controller IEEE-488 interface or RS-232 port using a
shielded interface cable.

2. Turn on the Model 2420 and the test equipment, and allo w them to w arm up for at least
one hour before performing calibration.

3. If you are using the IEEE-488 interface, make sure the primary address of the Model 2420
is the same as the address specified in the program you will be using to send commands.
(Use the MENU key and the COMMUNICATION menu to access the IEEE-488 address.)

Step 2: Voltage calibration

1. Connect the Model 2420 to the digital multimeter (see Figure 2-1), and select the multi­meter DC volts function.

2. Send the commands summarized in Table 2-8 in the order listed to initialize voltage cal­ibration. (When the :CAL:PROT:CODE command is sent, the instrument will assume
the operating states listed in Table 2-2.)

3. Perform the range calibration steps listed in Table 2-9 for all ranges. For each range:

• Send the :SOUR:VOLT:RANG command to select the source and sense range being

calibrated.. For example, for the 2V range, the following command would be sent

:SOUR:VOLT:RANG 2

• Program the source to output the negative full-range value using the :SOUR:VOLT

command.
For example:

:SOUR:VOLT -2

• Note and record the multimeter reading.

• Use the multimeter reading as the parameter for the :CAL:PRO T:SOUR and

• :CAL:PROT :SENS commands. F or example, a typical value for the 2V range w ould be:

:CAL:PROT:SOUR -1.998
:CAL:PROT:SENS -1.998

• Program the voltage source for 0V output using the :SOUR:VOLT 0.0 command.

• Note the multimeter reading.

• Send the source and sense calibration commands using the multimeter reading for the

parameter. For example:

:CAL:PROT:SOUR 1E-3
:CAL:PROT:SENS 1E-3

• Set the source to the positive full-range value using the :SOUR:VOLT command. For

example:

:SOUR:VOLT 2

Calibration 2-17

2-18 Calibration

• Note and record the multimeter reading.

• Send the source and sense commands using the multimeter reading as the parameter .
For example:

:CAL:PROT:SOUR 1.997
:CAL:PROT:SENS 1.997

• Send the SOUR:VOLT 0.0 command to set the source voltage to 0V.

• Note and record the multimeter reading.

• Send the :CAL:PROT :SOUR command using the multimeter reading as the command
parameter. For example:

:CAL:PROT:SOUR -1.02E-3

Table 2-8

Voltage calibration initialization commands

Command Description

*RST Restore GPIB defaults.
:SOUR:FUNC VOLT Activate voltage source.
:SENS:CURR:PROT 0.1 Current limit when voltage source is active.
:SENS:CURR:RANG 0.1 Make sure 1A range is not active.
:SOUR:VOLT:PROT MAX Maximum allowable source voltage.
:SYST:RSEN OFF Disable remote sensing. *
:CAL:PROT:CODE 'KI002420' Unlock cal.
:OUTP:STAT ON Turn source on.

* Remote sensing may be used if desired, but is not essential when using the recommended

digital multimeter. To use remote sensing, send :SYST:RSEN ON.

Calibration 2-19

Table 2-9

Voltage range calibration commands

Step Command/procedure* Description

1 :SOUR:VOLT:RANGE <Range> Select source range.
2 :SOUR:VOLT -<Source_value> Establish negative full-range polarity.
3 Take DMM reading. Read actual output value.
4 :CAL:PROT:SOUR <DMM_Reading> Calibrate sense function negative full scale.
5 Check 2420 for errors.
6 :CAL:PROT:SENS <DMM_Reading> Calibrate source function negative full scale.
7 Check 2420 for errors.
8 :SOUR:VOLT 0.0 Set output to 0V.
9 Take DMM reading. Read actual output value.
10 :CAL:PROT:SOUR <DMM_Reading> Calibrate sense function negative zero.
11 Check 2420 for errors.
12 :CAL:PROT:SENS <DMM_Reading> Calibration source function negative zero.
13 Check 2420 for errors.
14 :SOUR:VOLT +<Source_value> Establish positive full-range polarity.
15 Take DMM reading. Read actual output value
16 :CAL:PROT:SOUR <DMM_Reading> Calibrate sense function positive full scale.
17 Check 2420 for errors.
18 :CAL:PROT:SENS <DMM_Reading> Calibrate source function positive full scale.
19 Check 2420 for errors.
20 :SOUR:VOLT 0.0 Set output to 0V.
21 Take DMM reading. Read actual output value.
22 :CAL:PROT:SOUR <DMM_Reading> Calibrate source positive zero.

*1. Perform complete procedure for each range, where <Range> = 0.2, 2, 20, and 60, and

<Source_value> = 0.2, 2, 20, and 60.

2. <DMM_Reading> parameter is multimeter reading from previous step.

3. Use :SYST:ERR? query to check for errors.

Step 3: Current calibration

1. Connect the Model 2420 to the digital multimeter (see Figure 2-2), and select the multi­meter DC current function.

2. Send the commands summarized in Table 2-10 in the order listed to initialize current cal­ibration.

3. Calibrate the 10µA to 1A current ranges using the procedure summarized in T able 2-11.
For each range:

• Send the :SOUR:CURR:RANG command to select the source and sense range
being calibrated. For example, for the 1mA range, the command is:

:SOUR:CURR:RANG 1E-3

2-20 Calibration

• Program the source to output the negative full-range value using the
:SOUR:CURR command. For example:

:SOUR:CURR -1E-3

• Note and record the multimeter reading.

• Use the multimeter reading as the parameter for the :CAL:PROT:SOUR and

:CAL:PROT:SENS commands. For example, a typical value for the 1mA range
would be:

:CAL:PROT:SOUR -1.025E-3
:CAL:PROT:SENS -1.025E-3

• Program the current source for 0A output using the :SOUR:CURR 0.0 command.

• Note the multimeter reading.

• Send the source and sense calibration commands using the multimeter reading for

the parameter. For example:

:CAL:PROT:SOUR 1E-6
:CAL:PROT:SENS 1E-6

• Set the source to the positive full-range v alue using the :SOUR:CURR command.

For example, for the 1mA range:

:SOUR:CURR 1E-3

• Note and record the multimeter reading.

• Send the source and sense commands using the multimeter reading as the param-

eter. For example:

:CAL:PROT:SOUR 1.03E-3
:CAL:PROT:SENS 1.03E-3

• Send the :SOUR:CURR 0.0 command to set the source current to 0A.

• Note and record the multimeter reading.

• Send the :CAL:PROT:SOUR command using the multimeter reading as the com-

mand parameter. For example:

:CAL:PROT:SOUR 1E-6

4. Connect the 1Ω resistor and DMM to the Model 2420 INPUT/OUPUT jacks, as shown

in Figure 2-3. Select the DMM DC volts function.

5. Repeat step 3 for the 3A range using the calculated current as follows: I = V/R, where V

is the DMM voltage reading, and R is the characterized value of the 1Ω resistor.

Table 2-10

Current calibration initialization commands

Command Descripton

:SOUR:FUNC CURR Select source current mode.
:SENS:VOLT:PROT 20 Voltage limit when current source is active.
:SENS:VOLT:RANG 20 Make sure 60V range is not active.
:OUTP:STAT ON Turn source on.

Calibration 2-21

Table 2-11

Current range calibration commands

Step Command/procedure* Description

1

:SOUR:CURR:RANGE <Range>

2

:SOUR:CURR -<Source_value>

3

Take DMM reading.

4

:CAL:PROT:SOUR <DMM_Reading>

5

Check 2420 for errors.

6

:CAL:PROT:SENS <DMM_Reading>

7

Check 2420 for errors.

8

:SOUR:CURR 0.0

9

Take DMM reading.

10

:CAL:PROT:SOUR <DMM_Reading>

11

Check 2420 for errors.

12

:CAL:PROT:SENS <DMM_Reading>

13

Check 2420 for errors.

14

:SOUR:CURR +<Source_value>

15

Take DMM reading.

16

:CAL:PROT:SOUR <DMM_Reading>

17

Check 2420 for errors.

18

:CAL:PROT:SENS <DMM_Reading>

19

Check 2420 for errors.

20

:SOUR:CURR 0.0

21

Take DMM reading.

22

:CAL:PROT:SOUR <DMM_Reading>

*1. Perform complete procedure for each range, where <Range> and <Source_value> = 10E-6, 100E-6, 1E-3,

10E-3, 100E-3, 1, or 3.

2. <DMM_Reading> parameter is multimeter reading from previous step.

3. Use :SYST:ERR? query to check for errors.

Select source range.
Establish negative full-range polarity.
Read actual output value.
Calibrate sense function negative full scale.

Calibrate source function negative full scale.
Set output to 0A.

Read actual output value.
Calibrate sense function negative zero.

Calibration source function negative zero.
Establish positive full-range polarity.

Read actual output value.
Calibrate sense function positive full scale.

Calibrate source function positive full scale.
Set output to 0A.

Read actual output value.
Calibrate source positive zero.

Step 4: Program calibration dates

Use following commands to set the calibration date and calibration due date:

:CAL:PROT:DATE <year>, <month>, <day> (Calibration date)
:CAL:PROT:NDUE <year>, <month>, <day> (Next calibration due date)

Note that the year, month, and date must be separated by commas. The allowable range for

the year is from 1997 to 2096, the month is from 1 to 12, and the date is from 1 to 31.

Step 5: Save calibration constants

Calibration is now complete, so you can store the calibration constants in EER OM by sending

the following command:

:CAL:PROT:SAVE

2-22 Calibration

NOTE Calibration will be temporary unless you send the SAVE command. Also, calibra-

tion data will not be saved if (1) calibration is locked, (2) invalid data exists, or
(3) all steps were not completed.

Step 6: Lock out calibration

T o lock out further calibration, send the follo wing command after completing the calibration

procedure:

:CAL:PROT:LOCK

Single-range calibration

Normally, the complete calibration procedure should be performed to ensure that the entire
instrument is properly calibrated. In some instances, however, you may want to calibrate only
certain ranges. To do so, complete the entire procedure only for the range(s) to be calibrated.
Keep in mind, however, that you must complete all parameter steps for each source or sense
range. Also be sure to set calibration dates and save calibration after calibrating the desired
range(s).

3

Routine Maintenance

3-2 Routine Maintenance

CAUTION:FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.

CAUTION:FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.

WARNING:NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.

WARNING:NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.

Introduction

The information in this section deals with routine type maintenance that can be performed by
the operator.

Line fuse replacement

Figure 3-1

Rear panel

WARNING

Disconnect the line cord at the rear panel, and remove all test leads connect­ed to the instrument (front and rear) before replacing the line fuse.

The power line fuse is accessible from the rear panel, just abov e the AC po wer receptacle (see
Figure 3-1).

5V

HI

75V

PEAK

4-WIRE
SENSE

WITH FRONT PANEL MENU)

5V

PEAK

LO

INPUT/

OUTPUT

IEEE-488

(ENTER IEEE ADDRESS

75V

PEAK

PK

250V
PEAK

PEAK

5V

V, Ω,

GUARD

GUARD
SENSE

RS232

MADE IN

U.S.A.

TRIGGER

LINK

LINE FUSE

SLOWBLOW

3.15A, 250V

LINE RATING

90-250VAC

50, 60HZ

220VA MAX

INTERLOCK-

DIGITAL I/O

Perform the following steps to replace the line fuse:

1. Carefully grasp and squeeze together the locking tabs that secure the fuse carrier to the
fuse holder.

2. Pull out the fuse carrier, and replace the fuse with the type specified in Table 3-1.

CAUTION

To prevent instrument damage, use only the fuse type specified in Table 3-1.

3. Re-install the fuse carrier.

Routine Maintenace 3-3

NOTE

If the power line fuse continues to blow, a circuit malfunction exists and must be
corrected. Refer to the troubleshooting section of this manual for additional in­formation.

Table 3-1

Power line fuse

Line voltage Rating Keithley part no.

90-250V 250V, 3.15A, Slow

×

Blow 5

20mm

FU-106-3.15

3-4 Routine Maintenance

4

Troubleshooting

4-2 Troubleshooting

Introduction

This section of the manual will assist you in troubleshooting and repairing the Model 2420.
Included are self-tests, test procedures, troubleshooting tables, and circuit descriptions. Note
that disassembly instructions are located in Section 5, and component layout drawings are at the
end of Section 6.

WARNING

The information in this section is intended for qualified service personnel
only. Do not perform these procedures unless you are qualified to do so.
Some of these procedures may expose you to hazardous voltages that could
cause personal injury or death. Use caution when working with hazardous
voltages.

Repair considerations

Before making any repairs to the Model 2420, be sure to read the following considerations.

CAUTION

• Repairs will require various degrees of disassembly. However, it is recommended that
the Front Panel Tests be performed prior to any disassembly. The disassembly instruc­tions for the Model 2420 are contained in Section 5 of this manual.

• Do not make repairs to surface mount PC-boards unless equipped and qualified to do so
(see previous CAUTION).

• When working inside the unit and replacing parts, be sure to adhere to the handling pre­cautions and cleaning procedures explained in Section 5.

• Many CMOS devices are installed in the Model 2420. These static-sensitive devices
require special handling as explained in Section 5.

• Whenever a circuit board is remov ed or a component is replaced, the Model 2420 must
be recalibrated. See Section 2 for details on calibrating the unit.

The PC-boards are built using surface mount techniques and require special­ized equipment and skills for repair. If you are not equipped and/or qualified,
it is strongly recommended that you send the unit back to the factory for re­pairs or limit repairs to the PC-board replacement level. Without proper
equipment and training, you could damage a PC-board beyond repair.

Power-on self-test

During the power-on sequence, the Model 2420 will perform a checksum test on its EPROM

and test its RAM. If one of these tests fails, the instrument will lock up.

Front panel tests

There are three front panel tests: one to test the functionality of the front panel keys and tw o
to test the display . In the e vent of a test f ailure, refer to Display board checks for details on trou­bleshooting the display board.

KEYS test

The KEYS test lets you check the functionality of each front panel key . Perform the follo wing
steps to run the KEYS test.

1. Display the MAIN MENU by pressing the MENU key.

2. Select TEST, and press ENTER to display the SELF-TEST MENU.

3. Select DISPLAY-TESTS, and press ENTER to display the following menu:

FRONT PANEL TESTS

KEYS DISPLAY-PATTERNS CHAR-SET

4. Select KEYS, and press ENTER to start the test. When a key is pressed, the label name
for that key will be displayed to indicate that it is functioning properly. When the key is
released, the message “No keys pressed” is displayed.

5. Pressing EXIT tests the EXIT key. However, the second consecutive press of EXIT
aborts the test and returns the instrument to the SELF-TEST MENU. Continue pressing
EXIT to back out of the menu structure.

Troubleshooting 4-3

DISPLA Y P A TTERNS test

The display test lets you verify that each pixel and annunciator in the v acuum fluorescent dis-

play is working properly. Perform the following steps to run the display test:

1. Display the MAIN MENU by pressing the MENU key.

2. Select TEST, and press ENTER to display the SELF-TEST MENU.

3. Select DISPLAY-TESTS, and press ENTER to display the following menu:

FRONT PANEL TESTS

KEYS DISPLAY-PATTERNS CHAR-SET

4. Select DISPLAY-PATTERNS, and press ENTER to start the display test. There are five
parts to the display test. Each time a front panel key (except EXIT) is pressed, the next
part of the test sequence is selected. The five parts of the test sequence are as follows:

• Checkerboard pattern (alternate pixels on) and all annunciators.

• Checkerboard pattern and the annunciators that are on during normal operation.

• Horizontal lines (pixels) of the first digit are sequenced.

• Vertical lines (pixels) of the first digit are sequenced.

• Each digit (and adjacent annunciator) is sequenced. All the pixels of the selected digit

are on.

5. When finished, abort the display test by pressing EXIT . The instrument returns to the
FRONT P ANEL TESTS MENU. Continue pressing EXIT to back out of the menu structure.

4-4 Troubleshooting

CHAR SET test

The character set test lets you display all characters. Perform the following steps to run the

character set test:

1. Display the MAIN MENU by pressing the MENU key.

2. Select TEST, and press ENTER to display the SELF-TEST MENU.

3. Select DISPLAY-TESTS, and press ENTER to display the following menu:

FRONT PANEL TESTS

KEYS DISPLAY-PATTERNS CHAR-SET

4. Select CHAR-SET, and press ENTER to start the character set test. Press an y ke y except
EXIT to cycle through all displayable characters.

5. When finished, abort the character set test by pressing EXIT. The instrument returns to
the FRONT PANEL TESTS MENU. Continue pressing EXIT to back out of the menu
structure.

Principles of operation

The following information is provided to support the troubleshooting tests and procedures

covered in this section of the manual. Refer to the following drawings:

Figure 4-1 — Overall block diagram
Figure 4-2 — Analog circuitry block diagram
Figure 4-3 — Power supply block diagram
Figure 4-4 — Output stage simplified schematic
Figure 4-5 — Digital circuitry block diagram

Overall block diagram

Figure 4-1 shows an overall block diagram of the Model 2420. Circuitry may be divided into

three general areas:

• Analog circuits — includes sourcing circuits such as the DACs, clamps, output stage,
and feedback circuits, as well as measurement circuits such as the A/D converter.

• Digital circuits — includes the microcomputer that controls the analog section, front
panel, and GPIB and RS-232 ports, as well as associated interfacing circuits.

• Power supplies — converts the AC line voltage into DC voltages that supply the power
for the digital and analog circuits, and the output stage.

Analog circuits

Figure 4-2 shows the analog circuitry block.

Troubleshooting 4-5

Figure 4-1

Overall block
diagram

Display,

Keyboard

Digital

I/O

Trigger

Link

Front
Panel

Controller

Trigger,

Digital

I/O

DACs

Analog Section

Clamps

Feedback

A/D

Converter

Microcomputer

Digital Section

Output

Stage

RS-232

GPIB

Interface

Guard
Buffer

Output

Guard

RS-232 I/O

GPIB I/O

To Analog

CircuitsToOutput Stage

±15V

+5V ±42V

Analog

Power

Supply

Output

Stage
Power

Supply

Power Supply

To

Digital Circuits

±85V +5V +12V

Digital
Power
Supply

Line In

Figure 4-2

Analog circuitry block diagram

V DAC

I DAC

Control

FB

VFB

A/D

IFB

V Clamp

I Clamp

+7

MUX

Output

Stage

+42

+85

Sense

Resistors

O

Output

HI

S+

Output

LO

S-

VFB

Error
Amp

-42

-85

O

Remote

IFB

Protection

O

S

+

­Protection

Guard

Out

Guard

Sense

4-6 Troubleshooting

D/A converters control the programmed v oltage and current, or voltage compliance and current
compliance. Each DA C has two ranges, a 10V full-scale output or a 1V full-scale output. The D A C
outputs are fed to the summing node, FB. Either the V DA C or the I D A C has the ability to control
the main loop. If the unit is set for SV (source voltage), it will source voltage until the compliance
current is reached (as determined by the I DA C setting), and the current loop will o verride the volt­age loop. If, howev er , the unit is set for SI (source current), it will source current until the compli­ance voltage is reached (as determined by the V DAC setting), and the voltage loop will ov erride
the current loop. A priority bit in the Vclamp/I clamp circuit controls these functions.

The error amplifier adds open-loop gain and slew-rate control to the system to assure accura­cy and provide a controllable signal for the output stage, which provides the necessary voltage
and current gain to drive the output. Sense resistors in the HI output lead pro vide output current
sensing, and a separate sense resistor is used for each current range. The 1A and 3A ranges use

0.2V full-scale for a full-range output, while all other ranges use 2V output for full-scale current.
Voltage feedback is routed either internally or externally.

There are four voltage ranges: 0.2V, 2V, 20V, and 60V. The feedback gain changes only for
the 20V and 60V ranges, resulting in three unique feedback gain values. A multiplexer directs
the voltage feedback, current feedback, reference, or ground signal to the A/D converter. An
opto-isolated interface provides control signals for both DACs, analog circuit control, and A/D
converter communication to the digital section.

Power supply

Figure 4-3 shows a block diagram of the Model 2420 power delivery system.

Figure 4-3

Power supply block diagram

Line

Neutral

Analog Board

+15V +5V

FF F

Constant Frequency
Low Noise Floating
Switching Supply

D

PFC

DC/DC

Converter

F

+24Vdc

+24dc

D

-15V

Output Stage

-85V -42V +42V +85V

+12Vdc

DC

Regulators

+5Vdc

D

O

Digital

Circuits

The offline switching power supply provides all power for the instrument while providing
universal inputs and power factor correction for the 110/120V line. The digital board runs off
of 5V and 12V supplies derived from the switcher . The +12VD supply is set to program the flash
ROM. (See Digital circuitry below.)

A constant-frequency switching supply runs off the +24VD supplies and generates all the fl oat­ing and output supply voltages for the analog board: +5V and ±15V, ±42V and ±85V.

Output stage

Figure 4-4 shows a simplified schematic of the output stage.

Troubleshooting 4-7

Figure 4-4

Output stage simplified
schematic

Maindrive

O

+15Vf

300K

-15Vf

F

HI Drive

+

-

+85V

Q500

+42V

Q504

Q514

Q516

Q518

F

Q521

F

Q523

HI Drive

Q525

Q507

-42V

Q503

-85V

4-8 Troubleshooting

The Model 2420 output stage serves two purposes: (1) it converts signals from floating com­mon to output common, and (2) it provides both voltage and current amplification. The output
stage drive transistors are biased in class B configuration to prevent the possibility of thermal
runaway with high-current output values.

Output transistors Q518 and Q521 are cascoded with output MOSFETs Q516 and Q523. All
other MOSFETs and transistors are slaves, and the v oltages across these devices are determined
by the resistor-capacitor ladder circuits shown. High-current drive capability is provided by
Q500-Q511. Coarse current limits are built into the output stage.

A/D converter

The SourceMeter unit uses a multi-slope charge balance A/D converter with a single-slope
run-down. The converter is controlled by gate array U610. Commands are issued by the MPU
on the digital board through communications opto-isolators to U610, and U610 sends A/D read­ing data back through opto-isolators to the digital board for calibration and processing.

Active guard

The Model 2420 has an active guard or "six-wire ohms" circuit used to measure complex de­vices. This circuitry provides a low-current (50mA) equivalent of the voltage on output HI. If
the unit is in the SV mode, the low-current equivalent of the source voltage will appear on the
guard terminal. If the unit is in the SI mode, the voltage on output HI is equal to the source cur ­rent multiplied by the external resistance value. An equivalent voltage will be generated by the
guard circuit, and a guard sense terminal is provided to sense around the voltage drop in the
guard leads since significant current can flow (50mA).

Digital circuitry

Refer to Figure 4-5 for the following discussion on digital circuitry.

The core digital circuitry uses a Motorola 68332 microcontroller running at 16.78MHz. The
memory configuration includes two 256K X 8-bit flash EEPR OMs and two 128K X 8-bit RAMs
used in parallel to utilize the 16-bit data bus of the MPU. The RAM is battery backed-up, pro­viding continued storage of data buffer information during power-down c ycles, and flash ROM
support allows internal firmware upgrades using either the serial or GPIB port for downloading
new firmware. All calibration constants and the save 0 setup are stored in a separate serial EE­PROM. Setups 1 through 4 are stored in battery backed-up RAM.

External communication is provided via GPIB and serial interfaces. A 9914 GPIB IEEE-488
standard interface IC is used for the GPIB, and a 68332 Queued Serial Module (QSM) provides
the serial UART. For internal communications, the Time Processing Unit (TPU) is used for serial
communications with the front panel display module, and both the TPU and QSM handle digital­to-analog interfacing.

Troubleshooting 4-9

Figure 4-5

Digital circuitry
block diagram

A/D

Control/Data

Reset

2

E PROM

U17

A/D Interface

U9, U25

Voltage Source

Control

ROM

U15, U16

Microprocessor

U3

RAM

U12, U14

16.78MHz

Serial

Interface

U4

GPIB

U6, U13

U20

Digital I/O

Trigger

U23

U7

RS-232 Interface

IEEE-488 Interface

To Display

Board Controller

Trigger

Digital

I/O

Display board circuit theory

Display board components are shown in the digital circuitry block diagram in Figure 4-5.

U902 is the display microcontroller that controls the VFD (vacuum fluorescent display) and
interprets key data. The microcontroller has four peripheral I/O ports that are used for the v arious
control and read functions.

Display data is serially transmitted to the microcontroller from the digital board via the TXB
line to the microcontroller PD0 terminal. In a similar manner, key data is serially sent back to
the digital board through the RXB line via PD1. The 4MHz clock for the microcontroller is gen­erated on the digital board.

DS901 is the VFD (vacuum fluorescent display) module, which can display up to 49 charac­ters. Each character is organized as a 5
bar segment to act as a cursor.

The display uses a common multiplexing scheme with each character refreshed in sequence.
U903 and U904 are the grid drivers, and U901 and U905 are the dot dri vers. Note that dot dri ver
and grid driver data is serially transmitted from the microcontroller (PD3 and PC1).

×

7 matrix of dots or pixels and includes a long under-

4-10 Troubleshooting

The front panel keys (S901-S931) are organized into a row-column matrix to minimize the
number of microcontroller peripheral lines required to read the keyboard. A k ey is read by strob­ing the columns and reading all rows for each strobed column. K e y down data is interpreted by
the display microcontroller and sent back to the main microprocessor using proprietary encod­ing schemes.

T roubleshooting

Troubleshooting information for the various circuits is summarized below.

Display board checks

If the front panel display tests indicate that there is a problem on the display board, use Table
4-1. See Principles of operation for display circuit theory.

Table 4-1

Display board checks

Step Item/component Required condition Remarks

1
2
3

4
5
6

Front panel test
J1033
U902, pin 1

U902, pin 43
U902, pin32
U902, pine 33

Verify that all segments operate.
+5V, ±5%
Goes low briefly on power up, and
then goes high.
4MHz square wave.
Pulse train every 1 ms.
Brief pulse train when front panel key
is pressed.

Use front panel display test.
Digital +5V supply.
Microcontroller RESET.

Controller 4MHz clock.
Control from main processor.
Key down data sent to main
processor.

Power supply checks

Power supply problems can be checked out using Table 4-2. See Principles of operation for

circuit theory on the power supply.

Table 4-2

Power supply checks

Step Item.component Required condition Remarks

1
2

3
4
5
6
7
8
9

Line fuse
Line power

TP502
TP503
TP504
TP505
TP507
TP508
TP510

Digital circuitry checks

Digital circuit problems can be checked out using Table 4-3. See Principles of operation for

a digital circuit description.

Check continuity.
Plugged into live receptacle,
power on.
+80V, ±10%

-80V, ±10%
+38V, ±10%

-38V, ±10%
+15V, ±5%

-15V, ±5%
+5V, ±5%

Troubleshooting 4-11

Remove to check.
Check for correct power-up
sequence.
Referenced to TP501.
Referenced to TP501.
Referenced to TP501.
Referenced to TP501.
+15VF, referenced to TP500.

-15VF, referenced to TP500.
+5VF, referenced to TP500.

Table 4-3

Digital circuitry checks

Step Item/component Required condition Remarks

Verify that RAM and ROM are
functional.
All signals referenced to digital
common.
Digital logic supply.
MPU RESET line.
MPU address bus.
MPU data bus.
MPU clock.
RS-232 RX line.
RS-232 TX line.
IEEE-488 data bus.
IEEE-488 command lines.
IEEE-488 REN line.
IEEE-488 IFC line.
D_ADDATA
D_DATA
D_CLK
D_STB

10
11
12
13
14
15
16
17

Power-on test

1

U3 pin 19

2

U3 pin 7

3

U3 pin 68

4

U3, lines A0-A19

5

U3, lines D0-D15

6

U3 pin 66

7

U4 pin 7

8

U4 pin 8

9

U13 pins 34-42
U13 pins 26-31
U13 pin 24
U13 pin 25
U3 pin 43
U3 pin 44
U3 pin 45
U3 pin 47

RAM OK, ROM OK.
Digital common. common.
+5V

Low on power-up, then goes high.
Check for stuck bits.
Check for stuck bits.

16.78MHz.
Pulse train during RS-232 I/O.
Pulse train during RS-232 I/O.
Pulse train during IEEE-488 I/O.
Pulses during IEEE-488 I/O.
Low with remote enabled.
Low during interface clear.
Pulse train.
Pulse train.
Pulse train.
Pulse train

4-12 Troubleshooting

Analog circuitry checks

Table 4-4 summarizes analog circuitry checks.

Table 4-4

Analog circuitry checks

Step Item/component Required condition Remarks

1
2
3
4
5
6
7
8
9

*Measured with respect to FCOM (TP500).
**Measured with respect to OCOM (TP501).

TP200*
TP201*
TP202*
TP203*
TP213*
TP218**
TP219**
TP214**
TP232*

Battery replacement

>60V voltage protection
SOURCE +10V
SOURCE +10V (SVMI)
SOURCE +10V
SOURCE +10V
OUTPUT COM
OUTPUT COM
SVMI, OUTPUT ON, 20V
Bench defaults

-13V ±1V

-5V ±0.5V

-10V ±1V

-10.5V ±1V
0V ±0.1V
7V ±0.7V
7V ±0.7V
20V ±0.5V

6.4V ±0.6V

WARNING

The volatile memories of the Model 2420 are protected by a replaceable battery when po wer is
off. Typical battery life is approximately 10 years. The battery should be suspected if the instru­ment no longer retains buffer data or user -defined operating parameters such as instrument setups,
source memory , and math expressions. If the battery is absent or totally e xhausted, the display will
show the “Reading buf fer data lost” message shortly after the Model 2420 is switched on.

The battery is a 3V wafer-type lithium cell, Panasonic type BR-2330 or equivalent (Keithley
part number BA-46), which is located on the digital board. Replacement of the battery requires
removal of the case cover and analog board assembly. (See Section 5.)

Disconnect the instrument from the power line and all other equipment
before changing the battery.

Battery replacement precautions

WARNING

WARNING

There is a danger of explosion if battery is incorrectly replaced. Replace
only with the same or equivalent type recommended by the manufacturer.
Dispose of used batteries according to federal, state, and local laws.

The precautions below must be followed to avoid personal injury.

• Wear safety glasses or goggles when working with lithium batteries.

• Do not short the battery terminals together.

• Keep lithium batteries away from all liquids.

• Do not attempt to recharge lithium batteries.

• Observe proper polarity when inserting the battery in its holder.

• Do not incinerate or otherwise expose the battery to excessive heat (>60°C).

• Bulk quantities of lithium batteries should be disposed of as a hazardous
waste.

Battery replacement procedure

1. Remove the case cover and analog board assembly as covered in Section 5.

2. Locate the battery on the digital board.

3. Carefully unsolder and remove the old battery.

4. Install and solder the new battery in place.

5. Re-assemble the instrument, and turn it on. The “Reading buf fer data lost” error message
will be displayed.

6. Send the :SYST:MEM:INIT command via remote to perform the following:

• Clear the reading buffer.

• Initialize instrument setups 1 through 4 to present instrument settings.

• Initialize all 100 source memory locations to present instrument settings.

• Delete user math expressions.

No comm link error

A “No Comm Link” error indicates that the front panel processor has stopped communicating
with the main processor, which is located on the digital board. This error indicates that one of the
main processor ROMs may require re-seating in its sock et. ROMs may be reseated as follows:

1. Turn off the po wer, and disconnect the line cord and all other test leads and cables from
the instrument.

2. Remove the case cover as outlined in Section 5.

3. Remove the analog board assembly as outlined in Section 5.

4. Locate the two firmware ROMS, U15 and U16, located on the digital board. These are
the only ICs installed in sockets. (Refer to the component layout drawing at the end of
Section 6 for exact locations.)

5. Carefully push down on each ROM IC to make sure it is properly seated in its socket.

Troubleshooting 4-13

CAUTION

6. Connect the line cord, and turn on the power . If the problem persists, additional trouble­shooting will be required.

Be careful not to push down excessively, or you might crack the digital
board.

4-14 Troubleshooting

5

Disassembly

5-2 Disassembly

Introduction

This section explains how to handle, clean, and disassemble the Model 2420. Disassembly

drawings are located at the end of this section.

Handling and cleaning

T o av oid contaminating PC board traces with body oil or other foreign matter , av oid touching
the PC board traces while you are repairing the instrument. Motherboard areas covered by the
shield have high-impedance de vices or sensitive circuitry where contamination could cause de­graded performance.

Handling PC boards

Observe the following precautions when handling PC boards:

• Wear cotton gloves.

• Only handle PC boards by the edges and shields.

• Do not touch any board traces or components not associated with repair.

• Do not touch areas adjacent to electrical contacts.

• Use dry nitrogen gas to clean dust off PC boards.

Solder repairs

Observe the following precautions when you must solder a circuit board:

• Use an OA-based (organic activated) flux, and take care not to spread the flux to other
areas of the circuit board.

• Remove the flux from the work area when you have finished the repair by using pure
water with clean, foam-tipped swabs or a clean, soft brush.

• Once you have removed the flux, swab only the repair area with methanol, then blow­dry the board with dry nitrogen gas.

• After cleaning, allow the board to dry in a 50°C, low-humidity environment for several
hours.

Static sensitive devices

CMOS devices operate at very high impedance le vels. Therefore, an y static that b uilds up on
you or your clothing may be sufficient to destroy these de vices if the y are not handled properly.
Use the following precautions to avoid damaging them:

Disassembly 5-3

CAUTION

• Transport and handle ICs only in containers specially designed to prevent static build­up. Typically, you will receive these parts in anti-static containers made of plastic or
foam. Keep these devices in their original containers until ready for installation.

• Remove the devices from their protective containers only at a properly grounded work
station. Also, ground yourself with a suitable wrist strap.

• Handle the devices only by the body; do not touch the pins.

• Ground any printed circuit board into which a semiconductor device is to be inserted to
the bench or table.

• Use only anti-static type desoldering tools.

• Use only grounded-tip solder irons.

• Once the device is installed in the PC board, it is normally adequately protected, and you
can handle the boards normally.

Many CMOS devices are installed in the Model 2420. Handle all semicon­ductor devices as being static sensitive.

Assembly drawings

Use the assembly drawings located at the end of this section to assist you as you disassemble
and re-assemble the Model 2420. Also, refer to these drawings for information about the Kei­thley part numbers of most mechanical parts in the unit. Assembly drawings include:

• Front panel assembly — 2430-040

• Analog board/heat sink/shield assembly — 2430-050

• Chassis assembly — 2430-051

• Chassis/analog board assembly — 2430-052

• Final chassis assembly — 2430-053

Case cover removal

Follow the steps below to remove the case cover to gain access to internal parts.

WARNING

1.

Remove handle

gently pulling it away from the sides of the instrument case and swinging it up or do wn.
To remove the handle, swing the handle below the bottom surface of the case and back
until the orientation arrows on the handles line up with the orientation arrows on the
mounting ears. W ith the arro ws lined up, pull the ends of the handle a way from the case.

Before removing the case cover, disconnect the line cord and any test leads
from the instrument.

— The handle serves as an adjustable tilt-bail. Adjust its position by

5-4 Disassembly

2.

Remove mounting ears

and out on each mounting ear.

— Remove the screw that secures each mounting ear . Pull do wn

NOTE

NOTE

When re-installing the mounting ears, make sure to mount the right ear to the
right side of the chassis, and the left ear to the left side of the chassis. Eac h ear is
marked “RIGHT” or “LEFT” on its inside surface.

3.

Remove rear bezel

rear bezel to the chassis, then pull the bezel away from the case.

4.

Remove grounding screws

to the chassis. They are located on the bottom of the case at the back.

5.

Remove chassis

fully slide the chassis forward. Slide the chassis out of the metal case.

To gain access to the components under the analog board shield, remove the
shield, which is secured to the analog board by a single screw.

— T o remov e the case, grasp the front bezel of the instrument, and care-

Analog board removal

Perform the following steps to remove the analog board . This procedure assumes that the

case cover is already removed.

1. Disconnect the front and rear input terminals.
You must disconnect these input terminal connections for both the front and rear inputs:

• INPUT/OUTPUT HI and LO

• 4-WIRE SENSE HI and LO

•V,

Ω

, GUARD and GUARD SENSE (rear panel only)

Remove all the connections by pulling the wires off the pin connectors, then remove the fer­rite noise filters from the chassis. During re-assembly, use the following table to identify input
terminals:

— To remove the rear bezel, loosen the two screws that secure the

— Remove the two grounding screws that secure the case

Input terminals Front wire color Rear wire color

INPUT/OUTPUT HI
INPUT/OUTPUT LO
4-WIRE SENSE HI
4-WIRE SENSE LO

Ω

, GUARD

V,
GUARD SENSE

2. Unplug cables.

• Carefully unplug the ribbon cables at J1027, J1028, and J1029.

• Unplug the ON/OFF cable at J1034.

Red
Black
Yellow
Gray

-

-

White/Red
White/Black
White/Yellow
White/Gray
White
Blue/White

Disassembly 5-5

3. Remove screws.

• Remove the two fastening screws that secure the analog board assembly to the
chassis. These screws are located on the side of the board opposite from the heat sink.

• Remove the two screws that secure the heat sink to the chassis.

4. Remove analog board assembly.
After all screws have been removed, carefully lift the analog board assembly free of the
main chassis.

5. Disassemble analog board assembly.

• Remove the screws that secure the analog board and heat sink to the analog board
subchassis.

• Carefully remove the heat sink by sliding the clips off the power transistors.

CAUTION

NOTE

Be careful not to damage the heat sink insulation layer.

• Remove the analog board from the subchassis.

• Remove the four screws that secure the bottom co ver , then remov e the cover
from the bottom of the PC board.

When re-installing the heat sink, make sure that all clips are properly installed
and centered on each pair of output transistors.

Digital board removal

Perform the following steps to remov e the digital board. This procedure assumes that the an-

alog board assembly is already removed.

NOTE

In order to remove the digital board, the display board must first be removed.

1. Remove the IEEE-488, Digital I/O, and RS-232 fasteners.
The IEEE-488, Digital I/O, and RS-232 connectors each have two nuts that secure the
connectors to the rear panel. Remove these nuts.

2. Remove the POWER switch rod.
At the switch, place the edge of a flat-blade screw driver in the notch on the pushrod.
Gently twist the screw driver while pulling the rod from the shaft.

3. Unplug cables:

• Unplug the display board ribbon cable.

• Unplug the cables going to the power supply.

• Unplug the rear panel power module cable.

• The fan may need to be removed.

4. Remove digital board.
Slide the digital board forward until it is free of the guide pins, then remove the board.

During re-assembly , replace the board, and start the IEEE-488, Digital I/O, and RS-232
connector nuts and the mounting screw. Tighten all the fasteners once they are all in
place and the board is correctly aligned.

5-6 Disassembly

Front panel disassembly

Use the following procedures to remov e the display board and/or the pushb utton switch pad.

1. Unplug the display board ribbon cables.

2. Remove the front panel assembly.
This assembly has four retaining clips that snap onto the chassis over four pem nut studs.
Two retaining clips are located on each side of the front panel. Pull the retaining clips
outward and, at the same time, pull the front panel assembly forward until it separates
from the chassis.

3. Using a thin-bladed screw driver, pry the plastic PC board stop (located at the bottom of
the display board) until the bar separates from the casing. Pull the display board from the
front panel.

4. Remove the switch pad by pulling it from the front panel.

Removing power components

The following procedures to remove the power supply and/or power module require that the

case cover and motherboard be removed, as previously explained.

Power module removal

Perform the following steps to remove the rear panel power module:

1. Remove the analog board.

2. Unplug the cable connecting the power module to the digital board.

3. Disconnect the power module's ground wire. This green and yellow wire connects to a
threaded stud on the chassis with a kep nut.

4. Squeeze the latches on either side of the power module while pushing the module from
the access hole.

WARNING

To avoid electrical shock, which could result in injury or death, the ground
wire of the power module must be connected to chassis ground. When in­stalling the power module, be sure to re-connect the green and yellow
ground wire to the threaded stud on the chassis.

Instrument re-assembly

Re-assemble the instrument by reversing the previous disassembly procedures. Make sure
that all parts are properly seated and secured, and that all connections are properly made. To en­sure proper operation, replace the analog signal wire ferrite noise filters, and securely fasten the
shield.

Disassembly 5-7

WARNING

To ensure continued protection against electrical shock, verify that power
line ground (green and yellow wire attached to the power module) is con­nected to the chassis.

Also make sure the two bottom case screws are properly installed to secure
and ground the case cover to the chassis.

5-8 Disassembly

6

Replaceable Parts

6-2 Replaceable Parts

Introduction

This section contains replacement parts information and component layout drawings for the

Model 2420.

Parts lists

The electrical parts lists for the Model 2420 are shown tables at the end of this section. For
part numbers to the various mechanical parts and assemblies, use the Miscellaneous parts list
and the assembly drawings provided at the end of Section 5.

Ordering information

To place an order, or to obtain information concerning replacement parts, contact your Kei­thley representative or the f actory (see inside front cover for addresses). When ordering parts, be
sure to include the following information:

• Instrument model number (Model 2420)

• Instrument serial number

• Part description

• Component designation (if applicable)

• Keithley part number

Factory service

If the instrument is to be returned to Keithley Instruments for repair, perform the following:

• Call the Repair Department at 1-800-552-1115 for a Return Material Authorization
(RMA) number.

• Complete the service form at the back of this manual, and include it with the instrument.

• Carefully pack the instrument in the original packing carton.

• Write ATTENTION REPAIR DEPARTMENT and the RMA number on the shipping
label.

Component layouts

The component layouts for the various circuit boards are provided on the following pages.

Drawings include:

• Analog board — 2430-100

• Display board — 2400-110

• Digital board — 2420-140

Table 6-1

Analog board parts list

Replaceable Parts 6-3

Circuit designation Description

C200-203,205-210,225,226,231,
232,237,238

C204,411,608,609 CAP, .01UF, 10%, 50V CERAMIC C-491-.01
C211-214 CAP, 1000PF,10%, 50V, MONO CERAMIC C-452-1000P
C215-222,611 CAP,100PF, 5%, 100V, CERAMIC C-465-100P
C223,224,227-230,233-236, 239,240,

320
C241 CAP,1000PF,1%,50V,CERAMIC C-347-1000P
C242,243,248,249,
254,255,258-261,269-271 CAP, .1UF, 10%, 25V, CERAMIC C-495-.1
C246,336 CAP,3300PF,10%,100V,CERAMIC C-430-3300P
C247 CAP, .01, 5%, 50V, NPO C-514-.01
C250,251,272,290,291,297-

300,524,525
C256,257 CAP, 22PF, 10%, 100V, CERAMIC C-451-22P
C267,268,327 CAP, 1000P, 10%, 100V, CERAMIC C-451-1000P
C273-282,284-289,305-310,321,322 CAP, .1UF, 10%, 25V, CERAMIC C-495-.1
C283 CAP, 100P, 10%, 100V CERAMIC C-451-100P
C301,302 CAP, 1000PF,10%, 50V, MONO CERAMIC C-452-1000P
C311 CAP, 100UF, 20%, 10V, ALUM ELEC C-483-100
C312-319 CAP,10PF,5%,100V,CERAMIC C-372-10P
C323-326,603,604,615 CAP, 47P, 5%, 100V, CERAMIC C-465-47P
C328 CAP, 33PF, 10%, 100V, CERAMIC C-451-33P
C329 CAP, 220PF, 10%, 100V, CERAMIC C-451-220P
C331-334 CAP,100PF, 5%, 100V, CERAMIC C-465-100P
C400,401,296,330 CAP,270PF,2.5%,630V,POLYPROPYLENE C-405-270P
C409,410 CAP, .15UF,20%,50V, CERAMIC C-418-.15
C412 CAP, 1UF, 20%, 35V, TANTALUM C-494-1
C501,503 CAP, 47UF, 20%, 100V ALUM ELEC C-521-47
C502,504-506,550-553 CAP, .01U, 10%, 500V CERAMIC C-497-.01
C512,514 CAP, 22PF, 10%, 100V, CERAMIC C-451-22P

CAP, .1UF, 10%, 25V, CERAMIC C-495-.1

CAP, 33PF, 5%, 100V, CERAMIC C-465-33P

CAP, .1UF, 10%, 25V, CERAMIC C-495-.1

Keithley
part no.

6-4 Replaceable Parts

Table 6-1 (cont.)

Analog board parts list

Circuit designation Description

C513 CAP,560PF,2.5%,630V,POLYPROPYLENE C-405-560P
C515,541 CAP,.1UF, 20%,50V,CERAMIC C-418-.1
C522,523,526,527 CAP, 3300P, 10%, 500V, CERAMIC C-497-3300P
C528,533 CAP, 3300P, 10%, 500V, CERAMIC C-497-3300P
C534,535 CAP, 470UF, 20%, 63V ALUM ELEC C-477-470
C537-540 CAP, .1UF, 20%,100V, CERAMIC C-436-.1
C542,548,549,561,564 CAP, .1UF, 10%, 25V, CERAMIC C-495-.1
C543 CAP,10PF,10%,1000V,CERAMIC C-64-10P
C544-547 CAP, .01U, 10%, 500V CERAMIC C-497-.01
C558,565,566,600-602,605-

607,613,614,617
C610,612 CAP, 2200P, 10%, 100V CERAMIC C-430-2200P
C616,556,557,559,560,562,563 CAP, 22UF, 20%, 25V, TANTALUM C-440-22
C618-625,650-652,659-662,262,263 CAP, .1UF, 10%, 25V, CERAMIC C-495-.1
CR200-203,205,207,208,210,216-

221,235
CR206,209,230-233,400,401,222,223 DIODE,IN3595 RF-43
CR224,225,517,519 SCHOTTKY BARRIER RECTIFIER RF-119
CR236,602,212,213,518,522,204,211,

239
CR237 DIODE, DUAL SWITCHING, BAV99L RF-82
CR520,521 ULTRAFAST POWER RECTIFIER RF-105
CR600 DIODE, DUAL HSM-2822T31 RF-95
CR601 DIODE, SCHOTTKY, SD103C RF-113
HS1-HS5,400 HEAT SINK HS-38
J1027 CONN, HEADER STRAIGHT SOLDER

J1028 CONNECTOR, HEADER STRAIGHT

J1029 CONN, MALE, 5-PIN (MOLEX 42491) CS-784-5
J1034 LATCHING HEADER,FRICTON, SGL

CAP, .1UF, 10%, 25V, CERAMIC C-495-.1

DIODE, SWITCHING, MMBD914 RF-83

DIODE, SWITCHING, MMBD914 RF-83

PIN

SOLDER PIN

ROW

Keithley
part no.

CS-368-16

CS-368-14

CS-724-3

Table 6-1 (cont.)

Analog board parts list

Replaceable Parts 6-5

Circuit designation Description

K200-205 N.C RELAY, 1 FORMB, AQV214S RL-176
K206,207,208 RELAY RL-207
K211 RELAY, SURFACE MOUNT RL-188
L201,500,501 CHOKE, SHIELD BEAD CH-52
L600,601,602 FERRITE CHIP 600 OHM BLM32A07 CH-62
L603 FERRITE CHIP 600 OHM BLM32A07 CH-62
Q200-207,240,241 TRANS, N CHANNEL JFET, SNJ132199 TG-294
Q208,210,212,214,216,218 TRANS,NPN CATV SILICON,MPSH17 TG-221
Q209,211,213,215,217,219 TRANS,CURRENT REGULATOR,CR430 TG-219
Q220,225 TRANS,NPN SILICON,MJE340 TG-209
Q221,226 TRANS,PNP POWER,MJE350 TG-210
Q222,224 TRANS, N-CHAN JFET, SST4393 TG-263
Q234-239,244,246,255,256,

258,401,404,229
Q242,243 TRANS, N-CHAN MOSFET, TN254ON8 TG-274
Q247,520,601,529,228,248 TRANS, PNP, MMBT3906L TG-244
Q249 TRANS, NPN SILICON, BC846BL TG-278
Q250 TRANS PNP, BC 856BL TG-287
Q402,409 TRANS, N-CHAN DMOS FET TN2504N8 TG-261
Q403,406,407,408 TRANS, N-CHAN JFET, SST109 TG-266
Q405,410,411,602-605,223,420,502 TRANS, N-MOSFET, VN0605T TG-243
Q412,414 TRANS, N-MEGAFET, RFD 14N05LSM TG-267
Q415,416 TRANS, P-FET, MTP23P06 TG-229
Q417,419 N CHANNEL MEGAFET TG-339
Q418 TRANS, P-CHAN, MOSFET, TP0610T TG-259
Q500,503 TRANSISTOR, SMT TG-350
Q501,510,534,535,528,227,257,515,

517,519
Q504,514,516 TRANSISTOR TG-349
Q507,523,525 TRANSISTOR TG-348
Q518 TRANSISTOR TG-356

TRANS, N-MOSFET, VN0605T TG-243

TRANS, NPN, MMBT3904 TG-238

Keithley
part no.

6-6 Replaceable Parts

Table 6-1 (cont.)

Analog board parts list

Circuit designation Description

Q521 TRANSISTOR TG-357
Q522,524,600 TRANS, NPN, MMBT3904 TG-238
Q526,527,530,531 TRANS, N CHANNEL MOSFET,

SI9410DY
Q532 TRANS,N-CHANNEL FET,IRF630 TG-214
Q533 TRANS,P-CHANNEL 200V FET,IRF9630 TG-215
R117-128,133-136,141-144 RES, 10K, 5%, 250MW, METAL FILM R-376-10K
R129,211,224-

229,234237,244,247,281,282
R137-140,145-149 RES, 10K, 5%, 250MW, METAL FILM R-376-10K
R150,151,389,390,431,432,433,434,5

20,536
R152,291,293 RES, 42.7K, .1%, .125W,THIN FILM R-456-42.7K
R155,669 RES, 10K, 1%, 100MW, THICK FILM R-418-10K
R200,201,203,232,238 RESISTOR NETWORK, 10K-10K TF-236
R202,204,252,255,256,259,260,263,

264,267
R205,310,485,552,667 RES, .0499, 1%, 100MW, THICK FILM R-418-.0499
R207 RES, 20K, .1%, .125W THIN FILM R-456-20K
R210,208 RES, 768, 1%, 100MW, THICK FILM R-418-768
R212 RES, 332, 1%, 100MW, THICK FILM R-418-332
R213 RES NET 5K, .1%, 668A TF-243-5K
R216,221,274-279,223 RES, 20K, 1%, 100MW THICK FILM R-418-20K
R217,500,515 RES, 121K, 1%,100MW, THICK FILM R-418-121K
R218 RES, 80.6K, 1%, 100MW THICK FILM R-418-80.6K
R219,220,222,230,231,373,374,616,

700,701
R240,243,248,251,253,254,257,258,

261,262
R241,242,249,250,653,664 RES, 140K, 1%, 100MW THICK FILM R-418-140K
R265,266,311-

317,334,335,337,339,357,366
R268-271,209 RES, 1M, 1%, 100MW, THICK FILM R-418-1M

RES, 10K, 1%, 100MW, THICK FILM R-418-10K

RES, 1K, 1%, 100MW, THICK FILM R-418-1K

RES, 100K, 1%, 100MW THICK FILM R-418-100K

RES, 49.9K, 1%, 100MW THICK FILM R-418-49.9K

RES, 4.99K, 1%, 100MW THICK FILM R-418-4.99K

RES, 4.99K, 1%, 100MW THICK FILM R-418-4.99K

Keithley
part no.

TG-302

Table 6-1 (cont.)

Analog board parts list

Replaceable Parts 6-7

Circuit designation Description

R272,273,346-348,511,512 RES, 249K, 1%, 100MW, THICK FILM R-418-249K
R280 RES,4.02K,1%,100MW, THICK FILM R-418-4.02K
R283,287,297,299,349,350-

352,457,461
R284-286,288,301,358,504,

617,622,654,655
R289,303 RES, 20K, .1%, .125W THIN FILM R-456-20K
R292,338,527,528,533,535,544,

546,547
R294-296 RES, 100K, .1%, .125W, THIN FILM R-456-100K
R298,300,345 RES, 150K, 1%, 100MW, THICK FILM R-418-150K
R302,525,526 RES, .0499, 1%, 100MW, THICK FILM R-418-.0499
R308 RES, 1.5K, 1%, 100MW THICK FILM R-418-1.5K
R332,423,429,430,604,606 RES, 499, 1%, 100MW THICK FILM R-418-499
R340,343,361,362,365,369,336,353,

481
R341,342,505 RES, 13K, 1%, 100MW, THICK FILM R-418-13K
R354,437 RES, 560K, 5%, 250MW, METAL FILM R-376-560K
R363 RES NET, .1%, .1W TF-259
R364,370,371,372,402,403,404,416,

417,459
R367,424,425,426,601,603,605,608,6

26,702
R368 RES, 332, 1%, 100MW, THICK FILM R-418-332
R375,376 RES, 10, 10%, 100MW, THICK FILM R-418-10
R379-387,391,392 RES, 475, 1%, 100MW, THICK FILM R-418-475
R393-399,411,412,413,388,307 RES, 357, 1%, 100MW, THICK FILM R-418-357
R422 RES, 4.7K, 5%, 250MW, METAL FILM R-376-4.7K
R435,436 RES, 499, 1%, 100MW THICK FILM R-418-499
R450 RES, 200K, .1%, 1/10W METAL FILM R-263-200K
R452 RES, 21.93K, .1%, 1/10W METAL FILM R-263-21.93K
R453 RES,1.82K,.1%,1/10W,METAL FILM R-263-1.82K

RES, 30.1K, 1%, 100MW, THICK FILM R-418-30.1K

RES, 10K, 1%, 100MW, THICK FILM R-418-10K

RES, 100K, 1%, 100MW THICK FILM R-418-100K

RES, 1K, 1%, 100MW, THICK FILM R-418-1K

RES, 100K, 1%, 100MW THICK FILM R-418-100K

RES, 4.99K, 1%, 100MW THICK FILM R-418-4.99K

Keithley
part no.

6-8 Replaceable Parts

Table 6-1 (cont.)

Analog board parts list

Circuit designation Description

R454,455,469,470,471,467,468 RES, 100, .1%, 1/10W, METAL FILM R-263-100
R463,479,473 RES, 30.1K, 1%, 100MW, THICK FILM R-418-30.1K
R472,478,466,355,290,344,309 RES, 1K, 1%, 100MW, THICK FILM R-418-1K
R474 RESISTOR R-473-.2
R482,484,487 RES, 6.04K, 1%, 100MW THICK FILM R-418-6.04K
R483 RES, 2K, 1%, 100MW, THICK FILM R-418-2K
R488,562,600 RES, 100K, 1%, 100MW THICK FILM R-418-100K
R489,356,359,418-

421,456,458,460,462
R490 RES, 205, .1%, 1/10W, METAL FILM R-263-205
R501,514,570,571,705 RES, 249,1%, 100MW, THICK FILM R-418-249
R503,563 RES, 15k, 1%, 100MW, THICK FILM R-418-15K
R506,507 RES, 11K, 5%,250MW,METAL FILM R-376-11K
R508,509 RES, 11K, 5%,250MW,METAL FILM R-376-11K
R516,523 RES,4.02K,1%,100MW, THICK FILM R-418-4.02K
R517,524,564,565,566,567 RES, 12.1, 1%, 125MW METAL FILM R-391-12.1
R521 RES, 2M, 1%, 100MW, THICK FILM R-418-2M
R529,530,532,534 RES, 249,1%, 100MW, THICK FILM R-418-249
R537,451,531 RES, 1K, 1%, 100MW, THICK FILM R-418-1K
R538-543,568,569 RES,.5,5%,1W, METAL R-444-.5
R545 RES, 15k, 1%, 100MW, THICK FILM R-418-15K
R548,304-306 RES, 33, 5%, 250mW, METAL FILM R-376-33
R554 RES, 2.21K, 1%, 100MW, THICK FILM R-418-2.21K
R559 RES, 100, 1%, 100MW, THICK FILM R-418-100
R560,561 RES, 45.3K, 1%, 100MW THICK FILM R-418-45.3K
R602,607 RES, 150, 5%, 250MW, METAL FILM R-376-150
R609 RES NET TF-245
R610 RES, 1.28M, .1%, 1/8W METAL FILM R-176-1.28M
R611,621 RES, 475, 1%, 100MW, THICK FILM R-418-475
R612 RES, 5.11K, 1%, 100MW, THICK FILM R-418-5.11K
R613,624,659,660,558 RES, 100, 1%, 100MW, THICK FILM R-418-100

RES, 1K, 1%, 100MW, THICK FILM R-418-1K

Keithley
part no.

Table 6-1 (cont.)

Analog board parts list

Replaceable Parts 6-9

Circuit designation Description

R614,615,553 RES, 2.21K, 1%, 100MW, THICK FILM R-418-2.21K
R618 RES, 34K, 1%, 100MW, THICK FILM R-418-34K
R619 RES, 4.75K, 1%, 100MW, THICK FILM R-418-4.75K
R620 RES, 82.5, 1%, 100MW, THICK FILM R-418-82.5
R623 RES, 10, 10%, 100MW, THICK FILM R-418-10
R650,651 RES NET, 9K-1K, MICRO DIVIDER TF-246-2
R652,665 RES, 357, 1%, 100MW, THICK FILM R-418-357
R656 RES, 6.04K, .1%, .125W THIN FILM R-456-6.04K
R657,658 RES, 1M, 1%, 100MW, THICK FILM R-418-1M
R666 RES NET, 3K, 12K, 0.1%, 100MW THIN-

FILM
R703,153,154 RES, 4.99K, 1%, 100MW THICK FILM R-418-4.99K
R704,706,707,502,510 RES, 1K, 1%, 100MW, THICK FILM R-418-1K
R710 RESISTOR R-474-.065
RT200 POLYSWITCH, PTC RESISTOR RT-17
RT500 THERMISTER, PD=7MW/DEG C,

1500V,613.74K
TP218-225 CONN,TEST POINT CS-553
TP500-510,TP227,228,230-235,200-

215
U202,650,203 IC, OP AMP LT1112 IC-1048
U204,229 IC, 8-CHAN ANA MULTI-

U205,407 IC, HEX INVERTERS, 74HCT04 IC-880
U209,215 IC, QUAD COMPARATOR,LM339D IC-774
U210,220 IC, DUAL BIPOLAR OP-AMP, LT1124CS8 IC-955
U211,213 IC, BIFET OP AMP, AD712JR IC-834
U212,214,230,241,400-406,652 IC, CMOS ANAL SWITCH, DG444DY IC-866
U221,227 IC, DIFF. AMP, AMP03GP IC-988
U222 IC, OP-AMP, LTC1050CS8 IC-791
U223,411,507,508 IC, MOSFET DRIVER, TLP591B IC-877
U226,659 IC, 20V OP-AMP, LT1097S8 IC-767

CONN,TEST POINT CS-553

PLEXER,DG408DY

Keithley
part no.

TF-237-2

RT-8

IC-844

6-10 Replaceable Parts

Table 6-1 (cont.)

Analog board parts list

Circuit designation Description

U228,263 IC, OP-AMP, LOW NOISE LT1007CS8 IC-949
U231,219,235,234,262 IC, OP AMP, LOW POWER AD795JR IC-1052
U238,201 IC, CMOS ANA SWITCH SPST

MAX326CSE
U239 IC, QUAD 2-INPUT NAND, 74HC00M IC-781
U240 IC,POS NAND GATES/INVERT,74HCT14 IC-656
U242-247 IC,DUAL HIGH CMR/SPEED

OPTO,HCPL-2631
U252-256 IC 8 STAGE SHIFT CD74HC4094M IC-1026
U257 IC, SUPPLY VOLT SUPERVISOR,

TL7705A
U410,218,216,225 ICM DUAL J-FET OP-AMP, OP-282GS IC-968
U500 IC, OP-AMP, AD847JN IC-890
U501,506 IC, VOLT COMPARATOR LM393D IC-775
U503 IC,+5V VOL TAGE REGULA TOR,

LM2940CT
U504 IC,POS VOL TAGE

REG+15V,500MA,78M15
U505 IC,NEG VOLTAGE REG -15V,

500MA,79M15
U600,264,206,207,208,233 IC, DUAL PICOAMP OP-AMP AD706JR IC-910
U601 IC, QUAD D FLIP FLOP W/CLK,RESET

74HC175
U604 IC, NCHAN LAT DMOS QUAD-

FET,SD5400CY
U605 INTEGRATED CIRCUIT, OPA17 IC-960
U606,236 IC, HI-SPEED BIFET OP-AMP, AD711JR IC-894
U607 IC, OP-AMP, NE5534D IC-802
U608 IC, VOL T. COMP ARATOR,LM311M IC-776
U609 PROGRAMMED IC 2400-801-*
U651,602,603,224 IC, QUAD 2 IN NOR, 74HCT02 IC-809
U660,661 IC, 16 BIT DAC, AD7849BR IC-1004
VR200,201 DIODE, ZENER MM524694 TI DZ-113

Keithley
part no.

IC-909

IC-588

IC-860

IC-576

IC-194

IC-195

IC-923

IC-893

Table 6-1 (cont.)

Analog board parts list

Replaceable Parts 6-11

Circuit designation Description

VR202,203,407-409,506,507 DIODE,ZENER 5.1V, BZX84C5V1 DZ-88
VR214,215 DIODE, ZENER, 8.2V, MMBZ5237 DZ-92
VR400,401 DIODE, ZENER 4.7V, IN4732A DZ-67
VR410,601,604 DIODE, ZENER 3.3V, MMBZ5226BL DZ-94
VR500,501 DIODE, ZENER 6.0V, BZX84B6V2 DZ-87
VR502,503 DIODE ZENER 12V, MMSZ12T1 DZ-112
VR600 DIODE,ZENER 6.4V,IN4579 DZ-73
VR602,603 DIODE, ZENER, 6.2V MMSZ6V2 DZ-97
Y600 OSCILLATOR HIGH SPEED CMOS

12MHZ

Keithley
part no.

CR-37

6-12 Replaceable Parts

Table 6-2

Digital board parts list

Circuit designation Description

BT1 BATTERY BA-46
C1,3,77,11,14,16,17,20,22,23,25,26,30 CAP, .1UF, 10%, 25V, CERAMIC C-495-.1
C103 CAP, 100UF, 20%, 10V, ALUM ELEC C-483-100
C104 CAP,10UF,20%,63V,ALUM ELEC C-403-10
C105,108,109,111 CAP, 47UF, 20%, 100V ALUM ELEC C-521-47
C107,110 CAP A CITOR, ALUM ELEC C-554-82
C113,115,117,119 CAPACITOR SMT C-551-10
C114 CAP,100UF,20%,63V,ALUM ELEC C-403-100
C116 CAP, 100UF, 20%, 16V ALUM ELEC C-530-100
C120 CAP, 270PF, 5%, 100V, CERAMIC C-465-270P
C121 CAP, 390P, 10%, 100V, CERAMIC C-451-390P
C122 CAP, .47U, 20%, 25V C-520-.47
C19,69,85,75,92 CAP, .1UF, 10%, 25V, CERAMIC C-495-.1
C2,56,76,78,8,80,82,87,88,89,44,46 CAP, .01UF, 10%, 50V CERAMIC C-491-.01
C24,96 CAPACITOR, POLYESTER C-553-.1
C27,32,34,36 CAP, 1UF, 20%, 50V CERAMIC C-519-1
C28 CAP, 47P, 5%, 100V, CERAMIC C-465-47P
C31,50 CAP,100PF, 5%, 100V, CERAMIC C-465-100P
C33,63,74,93 CAP, .047U, 10%, 50V, CERAMIC C-491-.047
C35 CAP, 22UF, 20%, 25V, TANTALUM C-440-22
C39,41,42,49,59,66-68,79,81,48,83 CAP, .1UF, 10%, 25V, CERAMIC C-495-.1
C4,10 CAP, 15P, 1%, 100V CERAMIC C-512-15P
C43 CAP,.33UF,10%, 50V CERAMIC C-464-.33
C5 CAP, .1UF, 20%,100V, CERAMIC C-436-.1
C51 CAP,33PF,10%,1000V,CERAMIC C-64-33P
C54,60,45,53 CAPACITOR C-527-5000P
C55,15,21,29,37 CAP, .01, 5%, 50V, NPO C-514-.01
C57,58,38 CAP, 1000PF,10%, 50V, MONO CERAMIC C-452-1000P
C62,91 CAP, 10UF,20%, 25V, TANTALUM C-440-10
C65 CAP, .022UF, 10%, 50V CERAMIC C-491-.022
C72,86 CAP, 1UF, 20%, 50V CERAMIC C-519-1

Keithley
part no.

Table 6-2 (cont.)

Digital board parts list

Replaceable Parts 6-13

Circuit designation Description

C84,6,7,9,18,90,52,70,71,73,64,102 CAP, .1UF, 10%, 25V, CERAMIC C-495-.1
C94 CAP, 470UF, -20+100%, 16V ALUMINUM C-313-470
C96,106,112,118 CAP, 22UF, -10+100%, 35v ELECTRO-

LYTIC
C97 CAPACITOR, POLYESTER C-553-.47
C99 CAP, .01uF, 20%, 50V, CERAMIC C-418-.01
CR13 DIODE, DUAL HSM-2822T31 RF-95
CR14,15,22-24,5,32,33 DIODE, DUAL SWITCHING, BAV99L RF-82
CR1-4,35,37,38,39,47 ULTRAFAST POWER RECTIFIER RF-107
CR36,43,44,45,46 DIODE, ULTRAFAST, MUR860 RF-68
CR48,49 DIODE, SWITCHING, MMBD914 RF-83
CR6,12,40,41 ULTRAFAST POWER RECTIFIER RF-105
CR8,11,17,21,25-28,31,19 DIODE, SWITCHING, 250MA,BAV103 RF-89
CR9 RECTIFIER RF-120
F1 POLYSWITCH, SMD030-2 FU-103
F2 FUSE, 3A FU-107-1
HS1,2 HEAT SINK HS-38
J1002 CONN, MOLEX, 3-PIN CS-772-3
J1023 CONN,RIGHT ANGLE,24PIN CS-507
J1024 CONN, RT ANGLE, MALE, 9 PIN CS-761-9
J1025 CONN, MICRODIN W/GND FINGERS CS-792
J1026 CONN, D-SUB MALE, BOARDLOCK

TYPE
K1 RELAY, SURFACE MOUNT RL-188
L1 FERRITE CHIP 600 OHM BLM32A07 CH-62
L3 CHOKE CH-81
L4,5,6,7 CHOKE CH-89-1
LS1 BEEPER, 5V, 30MA, QMX-05 EM-6
P1027,1033 CABLE ASSEMBL Y CA-62-4B
P1028 CABLE ASSEMBLY CA-32-9B

Keithley
part no.

C-309-22

CS-848-9

6-14 Replaceable Parts

Table 6-2 (cont.)

Digital board parts list

Circuit designation Description

P1035 LATCHING HEADER,FRICTON, SGL

ROW
PS1 POWER SUPPLY PS-54-2A
Q1,3,4,5,6 TRANS, N-MOSFET, VN0605T TG-243
Q10 TRANS, NPN, MMBT3904 TG-238
Q2 TRANSISTOR TG-338
Q7,12,8 POWER MOSFET IRFZ346 TG-313
Q9 TRANS,TRIODE THYRIS-

TOR,MAC223A6
R1,37,43,44,45 RES, 2.21K, 1%, 100MW, THICK FILM R-418-2.21K
R10 RES, 332K,1%, 100MW, THICK FILM R-418-332K
R101 RES, 20K, 1%, 100MW THICK FILM R-418-20K
R102 RES, 100K, 1%, 100MW THICK FILM R-418-100K
R103,105 RES, 1K, 1%, 100MW, THICK FILM R-418-1K
R108,51 RES, 249K, 1%, 100MW, THICK FILM R-418-249K
R15,17,21,23,31,70,72,18,48,61,8,155 RES, 1K, 1%, 100MW, THICK FILM R-418-1K
R2,13,4,52,14,19,34,35,50,58,63,68,

62,75
R22 RES,4.02K,1%,100MW, THICK FILM R-418-4.02K
R25,28,49 RES, 4.75K, 1%, 100MW, THICK FILM R-418-4.75K
R30 RES, 100, 1%, 100MW, THICK FILM R-418-100
R33,39,92,95,29,36,42 RES, .0499, 1%, 100MW, THICK FILM R-418-.0499
R40,32,27,24 RES, 5.1K,5%, 125MW, METAL FILM R-375-5.1K
R41,56,96,98 RESISTOR, METAL FILM R-465-499K
R46 RES, 10, 10%, 100MW, THICK FILM R-418-10
R5 RES, 10M, 1%, 125MW, THICK FILM R-418-10M
R55 RES, 10M, 1%, 125MW, THICK FILM R-418-10M
R57 RES, 1M, 1%, 100MW, THICK FILM R-418-1M
R59 RES, 475, 1%, 100MW, THICK FILM R-418-475
R6,47 RES, 10K, 1%, 100MW, THICK FILM R-418-10K
R65 RES, 2.21K, 1%, 100MW, THICK FILM R-418-2.21K

RES, 10K, 1%, 100MW, THICK FILM R-418-10K

Keithley
part no.

CS-724-3

TG-172

Table 6-2 (cont.)

Digital board parts list

Replaceable Parts 6-15

Circuit designation Description

R66 RESISTOR, METAL FILM R-464-100K
R67 RES, 8.06K, 1%, .1W THICK FILM R-418-8.06K
R73,74,76,78-81,83,7,60,69,71,85-89 RES, 10K, 1%, 100MW, THICK FILM R-418-10K
R77 RES, 15k, 1%, 100MW, THICK FILM R-418-15K
R82 RES, 499, 1%, 100MW THICK FILM R-418-499
R84,109,110,38 RES, 10K, 1%, 100MW, THICK FILM R-418-10K
R9,11,12,16,20 RES,100,5%,250MW,METAL FILM R-376-100
R90 RESISTOR, THICK FILM R-418-1.07K
R93 RES, 6.81K, .1%, .125W THIN FILM R-456-6.81K
R94 RESISTOR, CERAMIC R-463-.1
R97,100 RES, 200, 1%, 100MW, THICK FILM R-418-200
R99,107 RES, 150K, 1%, 100MW, THICK FILM R-418-150K
RT101 INRUSH CURRENT LIMITER RT-23
RV1 VARISTOR VR-10
RV101 METAL OXIDE VARISTOR VR-7
S01,2 SOCKET PLCC-032-T-A SO-143-32
S1 SWITCH,PUSHBUTTON (6 POLE) SW-466
T1 TRANSFORMER TR-313A
T2 TRANSFORMER TR-312A
T3 TRANSFORMER TR-317A
TP1-12, 14-18 CONN,TEST POINT CS-553
U10 LARGE SCALE IC, SMT IC-980
U11 IC, VOLT COMPARATOR LM393D IC-775
U12,14 LARGE SCALE IC LSI-162-70
U13 IC, GPIB ADAPTER, 9914A LSI-123
U15 PROGRAMMED ROM 2400-803-*
U16 PROGRAM 2400-804-*
U17 IC, SERIAL EPROM 24LC16B LSI-153
U18 IC, REGULATOR SWITCHING

78ST105SC

U19 IC, SCHMITT-TRIGGER NAND GATE IC-950

Keithley
part no.

IC-1080

6-16 Replaceable Parts

Table 6-2 (cont.)

Digital board parts list

Circuit designation Description

Keithley
part no.

U2 IC, MICROMANAGER, DS12365-10 IC-884
U20 IC,OCTAL INTERFACE BUS,75160 IC-646
U21 IC, DUAL POWER MOSFET DRIVER,

IC-437

TSC426
U22 IC, DUAL D-TYPE F/F, 74HC74 IC-773
U23,25 IC,POS NAND GATES/INVERT,74HCT14 IC-656
U24 IC,TRIPLE 3 IN NAND,74F10 IC-659
U26 IC, VOLTAGE REGULATOR, LM340-12 IC-60
U3 MICROCONTROLLER, MC68332-FC LSI-161
U4 IC +5V RS-232 TRANSCEIVER, MAX202 IC-952
U5 IC, OP-AMP, AD705JR IC-814
U6 IC,OCTAL INTER BUS TRANS,75161 IC-647
U7 IC, 4-CHANNEL PWR DRIVER, 2549B IC-1044
U8 INTEGRATED CIRCUIT IC-1113
U9 IC, HEX INVERTERS, 74HCT04 IC-880
VR1 DIODE, ZENER 33V, IN4752A DZ-68
Y1 CRYSTAL, FSM327 CR-41

* Order current firmware revision level.

Table 6-3

Display board parts list

Replaceable Parts 6-17

Circuit designation Description

Keithley
part no.

C901 CAP,22UF, 20%, 6.3,TANTALUM C-417-22
C902,904,907,908,910 CAP, .1UF, 20%,100V, CERAMIC C-436-.1
C903,905,906,909,911 CAP,.1UF, 20%,50V,CERAMIC C-418-.1
C912 CAP, 2.2UF, 20%,100V, ALUM ELEC C-503-2.2
C913,914 CAP,100UF,20%,16V, T ANTALUM C-504-100
C915,916 CAP, 33PF, 10%, 100V, CERAMIC C-451-33P
CR901-904 DIODE, SWITCHING, 250MA,BAV103 RF-89
CR905,906 DIODE, SWITCHING, MMBD914 RF-83
DS901 VACUUM FLUORESCENT DISPLAY DD-51C
J1032 CONN,BERG CS-339
J1033 CONN, HEADER STRAIGHT SOLDER

CS-368-16

PIN
Q901,902 TRANS, NPN GEN PURPOSE BC868 TG-293
R901 RES NET, 15K, 2%, 1.875W TF-219-15K
R902 RES, 13K, 5%,125MW, METAL FILM R-375-13K
R903,904 RES, 4.7K, 5%, 250MW, METAL FILM R-376-4.7K
R905 RES, 1M, 5%, 125MW, METAL FILM R-375-1M
R906 RES,1K, 5% 250MW, METAL FILM R-376-1K
R907 RES, 240, 5%, 250MW, METAL FILM R-376-240
R908 RES, 10M, 5%, 125MW, METAL FILM R-375-10M
T901 TRANSFORMER, TDK, ER14.5 SERIES TR-300
U901,904,905 IC, LATCHED DRIVERS,UCN-5812EPF-1 IC-732
U902 PROGRAMMED ROM 7001-800-*
U903 IC, 32-BIT, SERIAL UCN5818EPF IC-830
VR901 DIODE, ZENER, 8.2V, MMBZ5237 DZ-92
Y901 CRYSTAL, 4MHZ CR-36-4M

*Order same revision level as current part.

6-18 Replaceable Parts

Table 6-4

Mechanical parts list

Description Keithley part no.

FAN FN-33-2
LINE FILTER LF-11
LUG LU-88
LED, HIGH POWER PL-94
CHASSIS ASSEMBL Y 2420-302A
REAR PANEL 2400-303B
CHASSIS 2420-301A
BANANA JACK, PUSH-IN BLACK BJ-14-0
BANANA JACK, PUSH-IN RED BJ-14-2
BANANA JACK, PUSH-IN BLUE BJ-14-6
BANANA JACK, PUSH-IN WHITE BJ-14-9
HOLDER, FERRITE 2001-367A
PC BOARD STOP 2001-371A
SWITCHPAD 2400-315A
HEAT SINK 2420-308A
BOTTOM SHIELD 2420-309A
DISPLAY LENS 2420-311A
COVER 2420-317A
BEZEL, REAR 428-303D
FOOT 428-319A
MOUNTING EAR, RIGHT 428-328E
HANDLE 428-329F
MOUNTING EAR, LEFT 428-338B
LENS, LED 6517-309A
POWER ROD 704-313A
CHOKE CH-58-1A
FOOT, EXTRUDED FE-22A
FOOT,RUBBER FE-6
FUSE FU-106-3.15