Agilent Technologies U1251A User manual

Agilent Technologies
Agilent U1251A and
U1252A
Handheld Digital
Multimeter
User’s and Service Guide

II Agilent U1251A/U1252A User’s and Service Guide
Notices
© Agilent Technologies, Inc. 2006–2013
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
U1251-90003
Edition
Eleventh Edition, March 7, 2013
Printed in Malaysia
Agilent Technologies, Inc.
3501 Stevens Creek Blvd.
Santa Clara, CA 95052 USA
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
U.S. Government Restricted Rights. Soft-
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).
Warranty
The material contained in this docu-
ment is provided “as is,” and is sub-
ject to being changed, without notice,
in future editions. Further, to the max-
imum extent permitted by applicable
law, Agilent disclaims all warranties,
either express or implied, with regard
to this manual and any information
contained herein, including but not
limited to the implied warranties of
merchantability and fitness for a par-
ticular purpose. Agilent shall not be
liable for errors or for incidental or
consequential damages in connec-
tion with the furnishing, use, or per-
formance of this document or of any
information contained herein. Should
Agilent 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 sep-
arate agreement shall control.
Accessories Warranty
Agilent offers warranty for product’s acces-
sories for up to 3 months from the end-user
acceptance date.
Standard Calibration Service
(optional)
Agilent offers an optional calibration service
contract for a period of 3 years from
end-user acceptance date.
Safety Notices
CAUTION
A CAUTION notice denotes a haz-
ard. It calls attention to an operat-
ing procedure, practice, or the like
that, if not correctly performed or
adhered to, could result in damage
to the product or loss of important
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 like that, if not correctly per-
formed or adhered to, could result
in personal injury or death. Do not
proceed beyond a WARNING
notice until the indicated condi-
tions are fully understood and
met.

Agilent U1251A/U1252A User’s and 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.
Category III 1000 V overvoltage protection Category IV 600 V overvoltage protection
Equipment protected throughout by
double insulation or reinforced
insulation
Earth (ground) terminal
Caution, risk of danger (refer to this manual
for specific Warning or Caution information) Caution, risk of electric shock
CAT IV
600 V
CAT III
1000 V

IV Agilent U1251A/U1252A User’s and Service Guide
Safety Information
This meter is safety-certified in compliance with EN/IEC 61010-1:2001, UL 61010-1 Second Edition and CAN/CSA
22.2 61010-1 Second Edition, CAT III 1000 V/ CAT IV 600 V Overvoltage Protection, Pollution Degree II. Use with
standard or compatible test probes.
General Safety Information
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 of design, manufacture, and intended use of the instrument. Agilent Technologies
assumes no liability for the customer’s failure to comply with these requirements.

Agilent U1251A/U1252A User’s and Service Guide V
WARNING
• When working above 70 VDC, 33 VAC RMS or 46.7 V peak, exercise caution – such
range pose a shock hazard.
• Do not measure more than the rated voltage (as marked on the meter) between
terminals, or between terminal and earth ground.
• Double-check the meter’s operation by measuring a known voltage.
• For current measurement, turn off circuit power before connecting the meter to the
circuit. Always place the meter in series with the circuit.
• When connecting probes, always connect the common test probe first. When
disconnecting probes, always disconnect the live test probe first.
• Detach test probes from the meter before you open the battery cover.
• Do not use the meter with the battery cover or part of the cover removed or loose.
• Replace the battery as soon as the low battery indicator flashes on screen. This is
to avoid false readings, which may lead to possible electric shock or personal injury.
• Do not operate the product in an explosive atmosphere or in the presence of
flammable gases or fumes.
• Inspect the case for cracks or missing plastic. Pay extra attention to the insulation
surrounding the connectors. Do not use the meter if it is damaged.
• Inspect the test probes for damaged insulation or exposed metal, and check for
continuity. Do not use the test probe if it is damaged.
• Do not use any other AC charger adaptor apart from the one certified by Agilent with
this product.
• Do not use repaired fuses or short-circuited fuse-holders. For continued protection
against fire, replace the line fuses only with fuses of the same voltage and current
rating and recommended type.
• Do not service or perform adjustments alone. Under certain condition, hazardous
voltages may exist, even with the equipment switched off. To avoid dangerous electric
shock, service personnel must not attempt internal service or adjustment unless
another person, capable of rendering resuscitation or first aid, is present.
• Do not substitute parts or modify equipment to avoid the danger of introducing
additional hazards. Return the product to Agilent Technologies Sales and Service
Office for service and repair to ensure the safety features are maintained.
• Do not operate damaged equipment as the safety protection features built into this
product may have been impaired, either through physical damage, excessive
moisture, or any other reason. Remove power and do not use the product until safe
operation can be verified by service-trained personnel. If necessary, return the
product to Agilent Technologies Sales and Service Office for service and repair to
ensure the safety features are maintained.

VI Agilent U1251A/U1252A User’s and Service Guide
CAUTION
•Turn off the circuit power and discharge all high-voltage capacitors in the circuit before
you perform resistance, continuity, diodes, or capacitance tests.
•Use the correct terminals, function, and range for your measurements.
•Never measure voltage when current measurement is selected.
•Use only recommended rechargeable battery. Ensure proper insertion of battery in the
meter, and follow the correct polarity.
•Disconnect test leads from all the terminals during battery charging.

Agilent U1251A/U1252A User’s and 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/electronic product in
domestic household waste.
The CSA mark is a registered
trademark of the Canadian Standards
Association.

VIII Agilent U1251A/U1252A User’s and 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/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
Technologies, or visit: www.agilent.com/environment/product for more
information.
Agilent Technologies, through Rechargeable Battery Recycling Corporation (RBRC), offers free and convenient
battery recycling options in the U.S. and Canada. Contact RBRC at 877-2-RECYCLE (877.273.2925) or online at:
http://www.call2recycle.org/ for the nearest recycling location.

Agilent U1251A/U1252A User’s and Service Guide IX
In This Guide…
1GettingStarted
This chapter contains information on the Agilent U1251A and U1252A
handheld multimeter front panel, rotary switch, keypad, display, terminals
and rear panel.
2 Making Measurements
This chapter contains information on how to make measurements using
the U1251A and U1252A handheld digital multimeter.
3 Functions and Features
This chapter contains information on the functions and features that are
available for the U1251A and U1252A digital multimeter.
4 Changing The Default Setting
This chapter shows you how to change the default factory settings of the
U1251A and U1252A and other available setting options
5 Maintenance
This chapter will go through how to troubleshoot the handheld digital
multimeter if any problems arise.
6 Performance Tests and Calibration
This chapter contains the performance test and the adjustment procedure.
7 Specifications
This chapter lists the product characteristics, specification assumptions
and the specifications of the U1251A and U1252A digital multimeters.

X Agilent U1251A/U1252A User’s and Service Guide
Declaration of Conformity (DoC)
The Declaration of Conformity (DoC) for this instrument is available on the
Web site. You can search the DoC by its product model or description.
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.

III
Abbreviated Book Title Variable (Edit this) XIII
Contents
1 Getting Started
Introducing the U12521A/U1252A Handheld Digital Multimeter 2
Check the shipment 3
Adjusting the tilt-stand 4
The rear panel at a glance 7
The keypad at a glance 9
The display at a glance 11
Selecting display with the Hz button 16
Selecting display with the Dual button 18
Selection display with the Shift button 20
The terminals at a glance 22
2 Making Measurements
Understanding The Measurement Instructions 24
Measuring Voltage 24
Measuring AC voltage 25
Measuring DC voltage 26
Measuring Current 27
µA & mA measurement 27
Percentage scale of 4 mA to 20 mA 29
A (ampere) measurement 31
Frequency Counter 32
Measuring Resistance, Conductance and Testing Continuity 34
Testing Diode s 38
Measuring Capacitance 41
Measuring Temperature 43
Alerts and Warning During Measurement 47

XIV Abbreviated Book Title Variable (Edit this)
III
Overload alert 47
Input warning 47
Charge terminal alert 48
3 Functions and Features
Dynamic Recording 50
Data Hold (Trigger Hold) 52
Refresh Hold 53
Null (Relative) 55
Decibel Display 57
1 ms Peak Hold 59
Data Logging 61
Manual logging 61
Interval logging 63
Reviewing logged data 65
Square Wave Output (for U1252A) 67
Remote Communication 71
4 Changing The Default Setting
Selecting Setup Mode 74
Setting Data Hold/Refresh Hold Mode 77
Setting Data Logging Mode 78
Setting Thermocouple Types (U1252A only) 79
Setting Reference Impedance for dBm Measurement 80
Setting Minimum Frequency Measurement 81
Setting Temperature Unit 82
Setting Auto Power Saving Mode 84
Setting Percentage (%) Scale Readout 86

III
Abbreviated Book Title Variable (Edit this) XV
Setting Beep Frequency 87
Setting Backlight Timer 88
Setting Baud Rate 89
Setting Parity Check 90
Setting Data Bit 91
Setting Echo Mode 92
Setting Print Mode 93
Returning to Default Factory Settings 94
5 Maintenance
Introduction 96
General maintenance 96
Battery replacement 96
Storage considerations 98
Charging the battery 98
Fuse checking procedure 105
Replacing the fuse 106
Troubleshooting 108
Replaceable Parts 109
To order replaceable parts 109
6 Performance Tests and Calibration
Calibration Overview 112
Closed-case electronic calibration 112
Agilent Technologies calibration services 112
Calibration interval 113
Adjustment is recommended 113
Recommended Test Equipment 114
Basic Operating Test 115
Backlit test 115

XVI Abbreviated Book Title Variable (Edit this)
III
Testing the display 115
Current terminal test 116
Charge terminal alert test 117
Test Considerations 118
Calibration Security 119
Performance Verification Tests 120
Unsecuring the instrument for calibration 128
Calibration process 131
Using the front panel for adjustments 132
Adjustments Consideration 133
Valid adjustment input values 134
Adjustment procedure 135
Finishing the adjustment 142
To read the calibration count 142
Calibration errors 143
7 Specifications
Product Characteristics 146
Measurement Category 149
Measurement category definition 149
Specification Assumptions 150
Electrical Specifications 151
DC Specifications 151
AC Specifications 153
AC+DC Specifications for U1252A 155
Capacitance Specifications 156
Temperature Specifications 156
Frequency Specifications 157
Duty Cycle and Pulse Width Specifications 157
Frequency Sensitivity Specifications 158

III
Abbreviated Book Title Variable (Edit this) XVII
Peak Hold Specifications 159
Frequency Counter Specifications for U1252A 160
Square Wave Output for U1252A 161
Operating Specifications 162
Display update rate (approximate) 162
Input impedance 163

XVIII Abbreviated Book Title Variable (Edit this)
III

Abbreviated Book Title Variable (Edit this) IX
List of Figures
Figure 1-1 Tilt-stand at 60° 4
Figure 1-2 Tilt-stand at 30° 4
Figure 1-3 Tilt-stand at hanging position 5
Figure 1-4 U1252A front panel 6
Figure 1-5 Rear panel 7
Figure 1-6 Rotary switch 8
Figure 1-7 U1252A keypad 9
Figure 1-8 Display symbols 11
Figure 1-9 U1252A connector terminals 22
Figure 2-1 Measuring AC voltage 25
Figure 2-2 Measuring DC voltage 26
Figure 2-3 Measuring mA and mA current 28
Figure 2-4 Measuring scale of 4-20 mA 30
Figure 2-5 A (ampere) current measurement 31
Figure 2-6 Measuring frequency 33
Figure 2-7 Measuring resistance 34
Figure 2-8 Audible continuity, conductance, and resistance
test. 35
Figure 2-9 Conductance measurement 37
Figure 2-10 Measuring forward bias of diode 39
Figure 2-11 Measuring reverse bias of diode 40
Figure 2-12 Capacitance measurements 42
Figure 2-13 Connecting the thermal probe into the non-compensa-
tion transfer adapter 44
Figure 2-14 Connecting the probe with adapter into the
multimeter 44
Figure 2-15 Surface temperature measurement 46
Figure 2-16 Input terminal warning 47
Figure 2-17 Charge terminal alert 48
Figure 3-1 Dynamic recording mode operation 51
Figure 3-2 Data hold mode operation 52
Figure 3-3 Refresh hold mode operation 54
Figure 3-4 Null (relative) mode operation 56
Figure 3-5 dBm/dBV display mode operation 58
Figure 3-6 1 ms peak hold mode operation 60
Figure 3-7 Hand (Manual) logging mode operation 62

X Abbreviated Book Title Variable (Edit this)
Figure 3-8 Full Log 62
Figure 3-9 Interval (Automatic) logging mode operation 64
Figure 3-10 Log review mode operation 66
Figure 3-11 Frequency adjustment for square wave output 68
Figure 3-12 Pulse width adjustment for square wave output 69
Figure 3-13 Duty cycle adjustment for Square Wave 70
Figure 3-14 Cable connection for remote communication 71
Figure 4-1 Data hold/Refersh hold setup 77
Figure 4-2 Data logging setup 78
Figure 4-3 Thermocouple type setup 79
Figure 4-4 Reference impedance for dBm measurement setup 80
Figure 4-5 Minimum frequency setup 81
Figure 4-6 Temperature unit setup 83
Figure 4-7 Auto power saving setup 85
Figure 4-8 % scale readout setup 86
Figure 4-9 Beep frequency setup 87
Figure 4-10 Backlit timer setup 88
Figure 4-11 Baud rate setup remote control 89
Figure 4-12 Parity check setup 90
Figure 4-13 Data bit setup for remote control 91
Figure 4-14 Echo mode setup for remote control 92
Figure 4-15 Print mode setup for remote control 93
Figure 4-16 Reset setup 94
Figure 5-1 9 V rectangular battery 97
Figure 5-2 Battery capacity display as trickle 100
Figure 5-3 Self-test 100
Figure 5-4 Charging mode 102
Figure 5-5 Charge end and trickle state 103
Figure 5-6 Battery charging procedure 104
Figure 5-7 Fuse replacement 107
Figure 6-1 LCD display 115
Figure 6-2 Input warning 116
Figure 6-3 Charge terminal alert 117

II
Abbreviated Book Title Variable (Edit this) XI
List of Tables
Ta b l e 1 - 1 Rotary switch description and functions 8
Ta b l e 1 - 2 Keypad desciption and functions 9
Ta b l e 1 - 3 General display symbols 12
Ta b l e 1 - 4 Priamry display symbols 13
Ta b l e 1 - 5 Secondary display symbols 14
Ta b l e 1 - 6 Analog bar range and counts 15
Ta b l e 1 - 7 Selecting display with the Hz button 16
Ta b l e 1 - 8 Selecting display with the Dual button 18
Ta b l e 1 - 9 Selecting display with the Shift button 20
Ta b l e 1 - 10 Terminal connections for different measuring
functions 22
Ta b l e 2 - 1 Numerical steps descriptions 24
Ta b l e 2 - 2 Percentage scale and measurement range 29
Ta b l e 2 - 3 Audible continuity measurement range 36
Ta b l e 4 - 1 Available setting options in Setup mode 75
Ta b l e 5 - 1 Battery voltage and corresponding percentage of charg-
es in standby and charging modes 100
Ta b l e 5 - 2 Error messages 101
Ta b l e 5 - 3 Measurement readings for fuse checking 106
Ta b l e 5 - 4 Fuse specifications 107
Ta b l e 5 - 5 Basic troubleshooting procedures 108
Ta b l e 6 - 1 Recommended Test Equipment 114
Ta b l e 6 - 2 Performance verification test steps 121
Ta b l e 6 - 3 Valid adjustment input values 134
Ta b l e 6 - 4 Adjustment table 137
Ta b l e 7 - 1 DC Accuracy ± (% of reading + Number of Least Signifi-
cant Digit) 151
Ta b l e 7 - 2 U1251A accuracy specifications ± (% of reading + num-
ber of LSD) for true RMS AC voltage 153
Ta b l e 7 - 3 U1251A accuracy specifications ± (% of reading + num-
ber of LSD) for true RMS AC current 153
Ta b l e 7 - 4 U1252A accuracy specifications ± (% of reading + num-
ber of LSD) for true RMS AC voltage 154
Ta b l e 7 - 5 U1252A accuracy specifications ± (% of reading + num-
ber of LSD) for true RMS AC current 154
Ta b l e 7 - 6 U1252A true RMS ac+dc voltage specifications 155

XII Abbreviated Book Title Variable (Edit this)
II
Ta b l e 7 - 7 U1252A true RMS ac+dc current specifications 155
Ta b l e 7 - 8 Capacitance specifications 156
Ta b l e 7 - 9 Temperature specifications 156
Ta b l e 7 - 10 Frequency specifications 157
Ta b l e 7 - 11 Duty cycle and pulse width specifications 157
Ta b l e 7 - 12 Frequency sensitivity and trigger level specifications for
voltage measurements 158
Ta b l e 7 - 13 Frequency sensitivity specifications for current
measurements 159
Ta b l e 7 - 14 Peak hold specifications for dc voltage and current
measurements 159
Ta b l e 7 - 15 Frequency counter (divide by 1) specifications 160
Ta b l e 7 - 16 Frequency counter (divide by 100 [4])
specifications 160
Ta b l e 7 - 17 Square wave output specifications 161
Ta b l e 7 - 18 Display update rate (approximate) 162
Ta b l e 7 - 19 Input Impedance 163