Agilent Technologies U1271A User manual

Agilent Technologies
Agilent U1271A/U1272A
Handheld Digital
Multimeter
Service Guide

II U1271A/U1272A Service Guide
Notices
© Agilent Technologies, Inc. 2010
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
U1271-90020
Edition
First Edition, December 27, 2010
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
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Technology Licenses
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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.

U1271A/U1272A 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.
Direct current (DC) Off (supply)
Alternating current (AC) On (supply)
Both direct and alternating current Caution, risk of electric shock
Three-phase alternating current Caution, risk of danger (refer to this manual
for specific Warning or Caution information)
Earth (ground) terminal Caution, hot surface
Protective conductor terminal Out position of a bi-stable push control
Frame or chassis terminal In position of a bi-stable push control
Equipotentiality Category III 1000 V overvoltage protection
Equipment protected throughout by
double insulation or reinforced
insulation
Category IV 600 V overvoltage protection
CAT III
1000 V
CAT IV
600 V

IV U1271A/U1272A Service Guide
Safety Considerations
Read the information below before using this multimeter. The descriptions
and instructions in this manual apply to the Agilent U1271A and U1272A
Handheld Digital Multimeters (hereafter referred to as the multimeter).
The model U1272A appears in all illustrations.
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.
WARNING
• Do not use the multimeter if it is damaged. Before you use the
multimeter, 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 multimeter.
• Do not operate the multimeter around explosive gas, vapor, or wet
environments.
• Do not apply more than the rated voltage (as marked on the
multimeter) between terminals, or between terminal and earth
ground.
• Never use the multimeter in wet conditions or when there is
water on the surface. If the multimeter is wet, ensure that the
multimeter is dried only by trained personnel.
• Before use, verify the multimeter's operation by measuring a
known voltage.

U1271A/U1272A Service Guide V
WARNING
• When measuring current, turn off the circuit power before
connecting the multimeter in the circuit. Remember to place the
multimeter in series with the circuit.
• When servicing the multimeter, 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.
• Be aware of the presence of hazardous voltage before using the
Low Pass Filter (LPF) function for voltage measurement. Voltages
measured are usually greater than what indicated on the
multimeter as the voltages with higher frequencies have been
filtered through the LPF function.
• Do not use the ZLOW (low input impedance) function (U1272A
only) to measure voltages in circuits that could be damaged by
this function’s low input impedance of 2 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 multimeter before you open the
battery cover.
• Do not operate the multimeter 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 U1271A/U1272A 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 –20 °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 70 °C
Altitude Up to 2000 meters
Pollution degree Pollution degree II
NOTE
The U1271A/U1272A Handheld Digital Multimeter complies with the following
safety and EMC requirements:
•EN/IEC 61010-1:2001
•ANSI/UL 61010-1:2004
•CAN/CSA-C22.2 No. 61010-1-04
•Commercial limits compliance with EN61326-1

U1271A/U1272A 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 U1271A/U1272A 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.

U1271A/U1272A Service Guide IX
Declaration of Conformity (DoC)
The Declaration of Conformity (DoC) for this instrument is available on the
Agilent Web site. 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 U1271A/U1272A Service Guide
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U1271A/U1272A 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
Current terminal input test 6
Calibration Process 8
Test considerations 8
Input connections 9
Performance Verification Tests 10
Calibration Security 18
Unsecuring the Instrument for Calibration 19
To unsecure the instrument from the front panel 19
To change the calibration security code 20
To reset the calibration security code to its factory default 21
Using the Front Panel for Adjustments 23
Adjustment considerations 23
Valid adjustment input values 24
Adjustment procedure 27
Exiting the adjustment mode 29
Calibration Count 30
Calibration Error Codes 31

XII U1271A/U1272A Service Guide
2 Service and Maintenance
Troubleshooting 34
Verifying the Fuse Health 35
Fuse Replacement 38
Returning the Instrument for Service 42
Replaceable Parts 43
To order replaceable parts 43
Types of Service Available 44
Extended service contracts 44
Obtaining Repair Service (Worldwide) 45

U1271A/U1272A Service Guide XIII
List of Figures
Figure 1-1 LCD display screen 5
Figure 1-2 A-Err display 6
Figure 1-3 μA-Err display 7
Figure 1-4 SECUr display 19
Figure 1-5 Calibration security code operation 20
Figure 1-6 SECUr display 21
Figure 1-7 SEr.no display 22
Figure 1-8 rEF display 23
Figure 1-9 rEF display 28
Figure 2-1 Testing Fuse 1 36
Figure 2-2 Testing Fuse 2 37
Figure 2-3 Replacing Fuse 1 39
Figure 2-4 Replacing Fuse 2 40
Figure 2-5 Positions of Fuse 1 and Fuse 2 41

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U1271A/U1272A 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 10
Ta b l e 1- 3 Adjustment input values 24
Ta b l e 1- 4 Calibration error codes 31
Ta b l e 2- 1 Operating checklist 34
Ta b l e 2- 2 Fuse displayed readings 35

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1
U1271A/U1272A 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
Current terminal input test 6
Calibration Process 8
Test considerations 8
Input connections 9
Performance Verification Tests 10
Calibration Security 18
Unsecuring the Instrument for Calibration 19
To unsecure the instrument from the front panel 19
To change the calibration security code 20
To reset the calibration security code to its factory default 21
Using the Front Panel for Adjustments 23
Adjustment considerations 23
Valid adjustment input values 24
Adjustment procedure 27
Exiting the adjustment mode 29
Calibration Count 30
Calibration Error Codes 31
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 U1271A/U1272A Service Guide
Agilent Calibration Services
Agilent Technologies offers calibration services at competitive
prices. When your instrument is due for calibration, contact
your local Agilent Service Center for recalibration. See
“Types of Service Available” on page 44 for more
information on the various calibration services offered.
Closed case calibration
The U1271A and U1272A 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
U1271A/U1272A 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 30 and
verify that all adjustments have been performed.

1 Calibration Procedures
Recommended Test Equipment
4 U1271A/U1272A 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 U1271A/U1272A accuracy
specification
DC current Fluke 5520A <20% of the U1271A/U1272A accuracy
specification
Resistance Fluke 5520A <20% of the U1271A/U1272A accuracy
specification
AC voltage Fluke 5520A <20% of the U1271A/U1272A accuracy
specification
AC current Fluke 5520A <20% of the U1271A/U1272A accuracy
specification
Frequency Fluke 5520A <20% of the U1271A/U1272A accuracy
specification
Capacitance Fluke 5520A <20% of the U1271A/U1272A accuracy
specification
Duty cycle Fluke 5520A <20% of the U1271A/U1272A accuracy
specification
Diode Fluke 5520A <20% of the U1271A/U1272A accuracy
specification
Temperature Fluke 5520A <20% of the U1271A/U1272A accuracy
specification
Short Shorting plug — a dual banana plug with a copper wire
shorting the two terminals