Agilent Technologies U1231A User manual

Agilent Technologies
Agilent U1231A, U1232A,
and U1233A Handheld
Digital Multimeter
Service Guide

II U1231A/U1232A/U1233A Service Guide
Notices
© Agilent Technologies, Inc. 2011 – 2012
No part of this manual may be reproduced in
any form or by any means (including elec-
tronic storage and retrieval or translation
into a foreign language) without prior agree-
ment and written consent from Agilent
Technologies, Inc. as governed by United
States and international copyright laws.
Manual Part Number
U1231-90035
Edition
Fourth Edition, May 4, 2012
Agilent Technologies, Inc.
5301, Stevens Creek Blvd.
Santa Clara, CA 95051 USA
Warranty
The material contained in this document is
provided “as is,” and is subject to change,
without notice, in future editions. Further,
to the maximum extent permitted by the
applicable law, Agilent disclaims all war-
ranties, either express or implied, with
regard to this manual and any information
contained herein, including but not limited
to the implied warranties of merchantabil-
ity and fitness for a particular purpose.
Agilent shall not be liable for errors or for
incidental or consequential damages in
connection with the furnishing, use, or
performance of this document or of any
information contained herein. Should Agi-
lent and the user have a separate written
agreement with warranty terms covering
the material in this document that conflict
with these terms, the warranty terms in
the separate agreement shall control.
Technology Licenses
The hardware and or software described in
this document are furnished under a license
and may be used or copied only in accor-
dance with the terms of such license.
Restricted Rights Legend
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ware and technical data rights granted to
the federal government include only those
rights customarily provided to end user cus-
tomers. Agilent provides this customary
commercial license in Software and techni-
cal data pursuant to FAR 12.211 (Technical
Data) and 12.212 (Computer Software) and,
for the Department of Defense, DFARS
252.227-7015 (Technical Data - Commercial
Items) and DFARS 227.7202-3 (Rights in
Commercial Computer Software or Com-
puter Software Documentation).
Safety Notices
CAUTION
A CAUTION notice denotes a haz-
ard. It calls attention to an operat-
ing procedure, practice, or the likes
of that, if not correctly performed
or adhered to, could result in dam-
age to the product or loss of impor-
tant data. Do not proceed beyond a
CAUTION notice until the indicated
conditions are fully understood and
met.
WARNING
A WARNING notice denotes a
hazard. It calls attention to an
operating procedure, practice, or
the likes of that, if not correctly
performed or adhered to, could
result in personal injury or death.
Do not proceed beyond a WARN-
ING notice until the indicated
conditions are fully understood
and met.

U1231A/U1232A/U1233A Service Guide III
Safety Symbols
The following symbols on the instrument and in the documentation
indicate precautions which must be taken to maintain safe operation of
the instrument.
DC (Direct current or voltage)
AC (Alternating current or voltage)
Earth (ground) terminal
Caution, risk of danger (refer to this manual for specific Warning
or Caution information)
Equipment protected throughout by
double insulation or reinforced
insulation
Category III 600 V overvoltage protection
CAT III
600 V

IV U1231A/U1232A/U1233A Service Guide
Safety Considerations
Read the information below before using this instrument.
The following general safety precautions must be observed during all
phases of operation, service, and repair of this instrument. Failure to
comply with these precautions or with specific warnings elsewhere in this
manual violates safety standards for design, manufacture, and intended
use of the instrument. Agilent Technologies assumes no liability for the
customer’s failure to comply with these requirements.
CAUTION
•Disconnect circuit power and discharge all high-voltage capacitors
before testing resistance, continuity, diodes, or capacitance.
•Use the proper terminals, function, and range for your
measurements.
•This device is for use at altitudes of up to 2,000 m.
•Never measure voltage when current measurement is selected.
•Always use the specified battery type. The power for the meter is
supplied with four standard AAA 1.5 V batteries. Observe the
correct polarity markings before you insert the batteries to ensure
proper insertion of the batteries in the meter.
•To avoid damage to the instrument from battery leakage:
•Always remove dead batteries immediately.
•Always remove the batteries and store them separately if the
instrument is not going to be used or is being stored for a long
period of time.
WARNING
• Do not use the meter if it is damaged. Before you use the meter,
inspect the case. Look for cracks or missing plastic. Pay
particular attention to the insulation surrounding the connectors.
• Inspect the test leads for damaged insulation or exposed metal.
Check the test leads for continuity. Replace damaged test leads
before you use the meter.

U1231A/U1232A/U1233A Service Guide V
WARNING
• Do not operate the meter around explosive gas, vapor, or wet
environments.
• Do not apply more than the rated voltage (as marked on the
meter) between terminals, or between terminal and earth ground.
• Never use the meter in wet conditions or when there is water on
the surface. If the meter is wet, ensure that the meter is dried only
by trained personnel.
• Before use, verify the meter's operation by measuring a known
voltage.
• When measuring current, turn off the circuit power before
connecting the meter in the circuit. Remember to place the meter
in series with the circuit.
• When servicing the meter, use only the specified replacement
parts.
• Use caution when working above 60 V DC, 30 V AC rms, or 42.4 V
peak. Such voltages pose a shock hazard.
• Do not use the VZLOW (low input impedance) function to measure
voltages in circuits that could be damaged by this function’s low
input impedance of 3 kΩ.
• When using the probes, keep your fingers behind the finger
guards on the probes.
• Connect the common test lead before you connect the live test
lead. When you disconnect the leads, disconnect the live test lead
first.
• Remove the test leads from the meter before you open the battery
cover.
• Do not operate the meter with the battery cover or portions of the
cover removed or loosened.
• To avoid false readings, which may lead to possible electric shock
or personal injury, replace the battery as soon as the low battery
indicator appears and flashes.

VI U1231A/U1232A/U1233A Service Guide
Environmental Conditions
This instrument is designed for indoor use and in an area with low
condensation. The table below shows the general environmental
requirements for this instrument.
Environmental conditions Requirements
Operating temperature Full accuracy from –10 °C to 55 °C
Operating humidity
Full accuracy up to 80% RH (relative
humidity) for temperature up to 30 °C,
decreasing linearly to 50% RH at 55 °C
Storage temperature –40 °C to 60 °C
Altitude Up to 2000 meters
Pollution degree Pollution degree II
NOTE
The U1231A/U1232A/U1233A Handheld Digital Multimeter complies with the
following safety and EMC requirements:
•EN 61010-1 (IEC 61010-1:2001) for CAT III 600 V
•ANSI/UL 61010-1:2004
•CAN/CSA-C22.2 No. 61010-1-04
•Commercial limits compliance with EN61326-1

U1231A/U1232A/U1233A Service Guide VII
Regulatory Markings
The CE mark is a registered trademark
of the European Community. This CE
mark shows that the product complies
with all the relevant European Legal
Directives.
The C-tick mark is a registered
trademark of the Spectrum
Management Agency of Australia. This
signifies compliance with
the Australia EMC Framework
regulations under the terms of the
Radio Communication Act of 1992.
ICES/NMB-001 indicates that this ISM
device complies with the Canadian
ICES-001.
Cet appareil ISM est confomre a la
norme NMB-001 du Canada.
This instrument complies with the
WEEE Directive (2002/96/EC) marking
requirement. This affixed product label
indicates that you must not discard
this electrical or electronic product in
domestic household waste.
The CSA mark is a registered
trademark of the Canadian Standards
Association.
This symbol indicates the time period
during which no hazardous or toxic
substance elements are expected to
leak or deteriorate during normal use.
Forty years is the expected useful life
of the product.

VIII U1231A/U1232A/U1233A Service Guide
Waste Electrical and Electronic Equipment (WEEE) Directive 2002/96/EC
This instrument complies with the WEEE Directive (2002/96/EC) marking
requirement. This affixed product label indicates that you must not discard
this electrical or electronic product in domestic household waste.
Product Category:
With reference to the equipment types in the WEEE directive Annex 1, this
instrument is classified as a “Monitoring and Control Instrument” product.
The affixed product label is as shown below.
Do not dispose in domestic household waste.
To return this unwanted instrument, contact your nearest Agilent Service
Centre, or visit
www.agilent.com/environment/product
for more information.

U1231A/U1232A/U1233A Service Guide IX
Declaration of Conformity (DoC)
The Declaration of Conformity (DoC) for this instrument is available on the
Agilent website. You can search the DoC by its product model or
description at the web address below.
http://regulations.corporate.agilent.com/DoC/search.htm
NOTE
If you are unable to search for the respective DoC, please contact your
local Agilent representative.

X U1231A/U1232A/U1233A Service Guide
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U1231A/U1232A/U1233A Service Guide XI
Table of Contents
1 Calibration Procedures
Agilent Calibration Services 2
Closed case calibration 2
Calibration interval 2
Other recommendations for calibration 3
Recommended Test Equipment 4
Basic Operating Test 5
Backlight test 5
Display test 5
Calibration Process 6
Test Considerations 7
Performance Verification Tests 8
Calibration Security 12
Unsecuring the Instrument for Calibration 13
To unsecure the instrument from the front panel 13
To change the calibration security code 15
To reset the calibration security code to its factory default 16
Using the Front Panel for Adjustments 18
Adjustment considerations 18
Adjustment procedure 19
Valid adjustment input values 21
Functional tests 24
Exiting the adjustment mode 26
Calibration Count 27
Calibration Error Codes 28

XII U1231A/U1232A/U1233A Service Guide
2 Service and Maintenance
Troubleshooting 30
Checking the Fuse 31
Fuse Replacement 33
Returning the Instrument for Service 35
Replaceable Parts 36
To order replaceable parts 36
Types of Service Available 37
Extended service contracts 37
Obtaining Repair Service (Worldwide) 38

U1231A/U1232A/U1233A Service Guide XIII
List of Figures
Figure 1-1 LCD display screen 5
Figure 1-2 SECU display 13
Figure 1-3 Calibration security code display 13
Figure 1-4 Calibration security code operation 14
Figure 1-5 CSEC display 15
Figure 1-6 Factory default calibration security code display 15
Figure 1-7 SErn display 16
Figure 1-8 Calibration security code display 16
Figure 1-9 Calibration reference value display 19
Figure 1-10 Vsense functional test 25
Figure 2-1 Testing the fuse 32
Figure 2-2 Replacing the fuse 34

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U1231A/U1232A/U1233A Service Guide XV
List of Tables
Ta b l e 1 - 1 Recommended test equipment 4
Ta b l e 1 - 2 Performance verification tests 8
Ta b l e 1 - 3 Adjustment input values 21
Ta b l e 1 - 4 Calibration error codes 28
Ta b l e 2 - 1 Operating checklist 30
Ta b l e 2 - 2 Fuse displayed readings 31

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1
U1231A/U1232A/U1233A Handheld Digital Multimeter
Service Guide
Agilent Technologies
1
Calibration Procedures
Agilent Calibration Services 2
Closed case calibration 2
Calibration interval 2
Other recommendations for calibration 3
Recommended Test Equipment 4
Basic Operating Test 5
Backlight test 5
Display test 5
Calibration Process 6
Test Considerations 7
Performance Verification Tests 8
Calibration Security 12
Unsecuring the Instrument for Calibration 13
To unsecure the instrument from the front panel 13
To change the calibration security code 15
To reset the calibration security code to its factory default 16
Using the Front Panel for Adjustments 18
Adjustment considerations 18
Adjustment procedure 19
Valid adjustment input values 21
Functional tests 24
Exiting the adjustment mode 26
Calibration Count 27
Calibration Error Codes 28
This chapter contains procedures for verifying the
instrument performance, as well as procedures for making
adjustments (calibration) where necessary.

1 Calibration Procedures
Agilent Calibration Services
2 U1231A/U1232A/U1233A Service Guide
Agilent Calibration Services
When your instrument is due for calibration, contact your
local Agilent Service Center for recalibration. See “Types of
Service Available” on page 37 for more information on the
various calibration services offered.
Closed case calibration
The U1231A/U1232A/U1233A handheld digital multimeter
features closed- case electronic calibration. In other words,
no internal electro- mechanical adjustment is required. This
instrument calculates correction factors based on the input
reference signals you feed into it during the calibration
process. The new correction factors are stored in nonvolatile
EEPROM memory until the next calibration (adjustment) is
performed.
The contents of this nonvolatile EEPROM memory will not
change even when the power is switched off.
Calibration interval
The instrument should be calibrated on a regular interval
determined by the measurement accuracy requirements of
your application.
A one- year interval is adequate for most applications.
Accuracy specifications are warranted only if calibration is
performed at regular intervals. Accuracy specifications are
not warranted beyond the one- year calibration interval.
Agilent does not recommend extending calibration intervals
beyond two years for any application.

Calibration Procedures 1
Agilent Calibration Services
U1231A/U1232A/U1233A Service Guide 3
Other recommendations for calibration
Specifications are only guaranteed within the specified
period from the last calibration. Agilent recommends that
readjustment should always be performed at whatever
calibration interval you select. This will ensure that the
instrument remains within its specifications until the next
calibration. This calibration criterion provides the best
long- term stability.
During performance verification tests, only the performance
data is collected; these tests do not guarantee that the
instrument will remain within the specified limits. The tests
are only for identifying which functions need adjustment.
Please refer to the “Calibration Count” on page 27 and
verify that all adjustments have been performed.

1 Calibration Procedures
Recommended Test Equipment
4 U1231A/U1232A/U1233A Service Guide
Recommended Test Equipment
The test equipment recommended for the performance
verification and adjustment procedures is listed below in
Table 1- 1. If the exact instrument is not available, substitute
with another calibration standard of equivalent accuracy.
Table 1- 1 Recommended test equipment
Application Recommended
equipment Recommended accuracy requirements
DC voltage Fluke 5520A <20% of the instrument accuracy
specification
DC current Fluke 5520A <20% of the instrument accuracy
specification
Resistance Fluke 5520A <20% of the instrument accuracy
specification
AC voltage Fluke 5520A <20% of the instrument accuracy
specification
AC current Fluke 5520A <20% of the instrument accuracy
specification
Frequency Fluke 5520A <20% of the instrument accuracy
specification
Capacitance Fluke 5520A <20% of the instrument accuracy
specification
Diode Fluke 5520A <20% of the instrument accuracy
specification
Temperature Fluke 5520A <20% of the instrument accuracy
specification
Short Shorting plug — a dual banana plug with a copper wire
shorting the two terminals