Agilent Technologies U1251B Manual

Agilent Technologies
Agilent U1251B and
U1252B Handheld Digital
Multimeter
User’s and Service Guide

II Agilent U1251B/U1252B User’s and Service Guide
Notices
© Agilent Technologies, Inc. 2009–2013
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
U1251-90036
Edition
Tenth Edition, August 12, 2013
Printed in Malaysia
Agilent Technologies, Inc.
5301 Stevens Creek Blvd.
Santa Clara, CA 95051 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
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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).
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 U1251B/U1252B 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.
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 Agilent U1251B/U1252B 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.
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 U1251B/U1252B 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.
•Forcurrentmeasurement, 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 U1251B/U1252B User’s and Service Guide
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.

Agilent U1251B/U1252B User’s and Service Guide VII
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.

VIII Agilent U1251B/U1252B User’s and Service Guide
In This Guide…
1GettingStarted
This chapter contains information on the Agilent U1251B and U1252B
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 U1251B and U1252B handheld digital multimeter.
3 Functions and Features
This chapter contains information on the functions and features that are
available for the U1251B and U1252B digital multimeter.
4 Changing The Default Setting
This chapter shows you how to change the default factory settings of the
U1251B and U1252B 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 procedures and the
adjustment procedure.
7 Specifications
This chapter lists the product characteristics, specification assumptions
and the specifications of the U1251B and U1252B digital multimeters.

Agilent U1251B/U1252B User’s and Service Guide IX
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.

X Agilent U1251B/U1252B User’s and Service Guide

Agilent U1251B/U1252B User’s and Service Guide XIII
Contents
1 Getting Started
Introducing the U1251B/U1252B Handheld Digital Multimeter 2
Check the shipment 3
Adjusting the tilt-stand 4
The front panel at a glance 6
The rear panel at a glance 7
The rotary switch at a glance 8
The keypad at a glance 9
The display at a glance 11
Selecting display with the Hz button 15
Selecting display with the Dual button 17
Selecting 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 AC and DC Signals (U1252B only) 27
Measuring Current 28
µA & mA measurement 28
Percentage scale of 4 mA to 20 mA 30
A (ampere) measurement 32
Frequency Counter 33
Measuring Resistance, Conductance and Testing Continuity 35
Testing Diode s 40

XIV Agilent U1251B/U1252B User’s and Service Guide
Measuring Capacitance 43
Measuring Temperature 45
Alerts and Warning During Measurement 49
Overload alert 49
Input warning 49
Charge terminal alert 50
3 Functions and Features
Dynamic Recording 52
Data Hold (Trigger Hold) 54
Refresh Hold 55
Null (Relative) 57
Decibel Display 59
1 ms Peak Hold 61
Data Logging 63
Manual logging 63
Interval logging 65
Reviewing logged data 67
Square Wave Output (for U1252B) 69
Remote Communication 73
4 Changing The Default Setting
Selecting Setup Mode 76
Setting Data Hold/Refresh Hold Mode 80
Setting Data Logging Mode 81
Setting Thermocouple Types (U1252B only) 82
Setting Reference Impedance for dBm Measurement 83

Agilent U1251B/U1252B User’s and Service Guide XV
Setting Minimum Frequency Measurement 84
Setting Temperature Unit 85
Setting Auto Power Saving Mode 87
Setting Percentage (%) Scale Readout 89
Setting Beep Frequency 90
Setting Backlight Timer 91
Setting Baud Rate 92
Setting Parity Check 93
Setting Data Bit 94
Setting Echo Mode 95
Setting Print Mode 96
Returning to Default Factory Settings 97
Setting the Battery Voltage 98
Setting the Filter 99
5 Maintenance
Introduction 102
General maintenance 102
Battery replacement 102
Storage considerations 104
Charging the battery 105
Fuse checking procedure 112
Replacing the fuse 114
Troubleshooting 116
Replaceable Parts 118
To order replaceable parts 118

XVI Agilent U1251B/U1252B User’s and Service Guide
6 Performance Tests and Calibration
Calibration Overview 120
Closed-case electronic calibration 120
Agilent Technologies calibration services 120
Calibration interval 121
Adjustment is recommended 121
Recommended Test Equipment 122
Basic Operating Test 123
Backlit test 123
Testing the display 123
Current terminal test 124
Charge terminal alert test 125
Test Considerations 126
Calibration Security 127
Performance Verification Tests 128
Unsecuring the instrument for calibration 136
Calibration Process 139
Using the front panel for adjustments 140
Adjustments Consideration 141
Valid adjustment input values 142
Adjustment Procedure 143
Finishing the Adjustment 150
To Read the Calibration Count 150
Calibration Errors 151
7 Specifications
Product Characteristics 154
Measurement Category 157
Measurement category definition 157

Agilent U1251B/U1252B User’s and Service Guide XVII
Specification Assumptions 158
Electrical Specifications 158
DC Specifications 158
AC Specifications 161
AC+DC Specifications for U1252B 163
Capacitance Specifications 164
Temperature Specifications 164
Frequency Specifications 165
Duty Cycle and Pulse Width Specifications 165
Frequency Sensitivity Specifications 166
Peak Hold Specifications 168
Frequency Counter Specifications for U1252B 168
Square Wave Output for U1252B 169
Operating Specifications 171
Display update rate (approximate) 171
Input impedance 172

XVIII Agilent U1251B/U1252B User’s and Service Guide

Agilent U1251B/U1252B User’s and Service Guide 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 U1252B front panel 6
Figure 1-5 Rear panel 7
Figure 1-6 Rotary switch 8
Figure 1-7 U1252B keypad 9
Figure 1-8 Display symbols 11
Figure 1-9 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 29
Figure 2-4 Measuring scale of 4-20 mA 31
Figure 2-5 A (ampere) current measurement 32
Figure 2-6 Measuring frequency 34
Figure 2-7 Measuring resistance 36
Figure 2-8 Audible continuity, conductance, and resistance
test. 37
Figure 2-9 Conductance measurement 39
Figure 2-10 Measuring forward bias of diode 41
Figure 2-11 Measuring reverse bias of diode 42
Figure 2-12 Capacitance measurements 44
Figure 2-13 Connecting the thermal probe into the non-compensa-
tion transfer adapater 46
Figure 2-14 Connecting the probe with adapter into the
multimeter 46
Figure 2-15 Surface temperature measurement 48
Figure 2-16 Input terminal warning 49
Figure 2-17 Charge terminal alert 50
Figure 3-1 Dynamic recording mode operation 53
Figure 3-2 Data hold mode operation 54
Figure 3-3 Refresh hold mode operation 56
Figure 3-4 Null (relative) mode operation 58
Figure 3-5 dBm/dBV display mode operation 60
Figure 3-6 1 ms peak hold mode operation 62
Figure 3-7 Hand (Manual) logging mode operation 64

X Agilent U1251B/U1252B User’s and Service Guide
Figure 3-8 Full Log 64
Figure 3-9 Interval (Automatic) logging mode operation 66
Figure 3-10 Log review mode operation 68
Figure 3-11 Frequency adjustment for square wave output 70
Figure 3-12 Duty cycle adjustment for square wave output 71
Figure 3-13 Pulse width adjustment for square wave output 72
Figure 3-14 Cable connection for remote communication 73
Figure 4-1 Data hold/Refresh hold setup 80
Figure 4-2 Data logging setup 81
Figure 4-3 Thermocouple type setup 82
Figure 4-4 Reference impedance for dBm measurement setup 83
Figure 4-5 Minimum frequency setup 84
Figure 4-6 Temperature unit setup 86
Figure 4-7 Auto power saving setup 88
Figure 4-8 % scale readout setup 89
Figure 4-9 Beep frequency setup 90
Figure 4-10 Backlit timer setup 91
Figure 4-11 Baud rate setup remote control 92
Figure 4-12 Parity check setup 93
Figure 4-13 Data bit setup for remote control 94
Figure 4-14 Echo mode setup for remote control 95
Figure 4-15 Print mode setup for remote control 96
Figure 4-16 Reset setup 97
Figure 4-17 Battery voltage selection 98
Figure 4-18 DC filter 99
Figure 5-1 9 V rectangular battery 104
Figure 5-2 Battery capacity display as trickle 107
Figure 5-3 Self-test 108
Figure 5-4 Charging mode 110
Figure 5-5 Charge end and trickle state 110
Figure 5-6 Battery charging procedure 111
Figure 5-7 Fuse checking procedures 112
Figure 5-8 Fuse replacement 115
Figure 6-1 LCD display 123
Figure 6-2 Input warning 124
Figure 6-3 Charge terminal alert 125

Agilent U1251B/U1252B User’s and Service Guide XI
List of Tables
Ta b l e 1 - 1 Rotary switch description and functions 8
Ta b l e 1 - 2 Keypad descriptions and functions 9
Ta b l e 1 - 3 General display symbols 12
Ta b l e 1 - 4 Primary 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 30
Ta b l e 2 - 3 Audible continuity measurement range 37
Ta b l e 4 - 1 Available setting options in Setup mode 77
Ta b l e 4 - 2 Filter defaults 100
Ta b l e 5 - 1 Battery voltage and corresponding percentage of charg-
es in standby and charging modes 106
Ta b l e 5 - 2 Error messages 108
Ta b l e 5 - 3 Measurement readings for fuse checking 113
Ta b l e 5 - 4 Fuse specifications 115
Ta b l e 5 - 5 Basic troubleshooting procedures 116
Ta b l e 6 - 1 Recommended Test Equipment 122
Ta b l e 6 - 2 Verification Test 129
Ta b l e 6 - 3 Valid adjustment input values 142
Ta b l e 6 - 4 Adjustment table 145
Ta b l e 6 - 5 Calibration error codes and their respective
meanings 151
Ta b l e 7 - 1 DC Accuracy ± (% of reading + Number of Least Signifi-
cant Digit) 158
Ta b l e 7 - 2 U1251B accuracy specifications ± (% of reading + num-
ber of LSD) for true RMS AC voltage 161
Ta b l e 7 - 3 U1251B accuracy specifications ± (% of reading + num-
ber of LSD) for true RMS AC current 161
Ta b l e 7 - 4 U1252B accuracy specifications ± (% of reading + num-
ber of LSD) for true RMS AC voltage 162

XII Agilent U1251B/U1252B User’s and Service Guide
Ta b l e 7 - 5 U1252B accuracy specifications ± (% of reading + num-
ber of LSD) for true RMS AC current 162
Ta b l e 7 - 6 U1252B true RMS ac+dc voltage specifications 163
Ta b l e 7 - 7 U1252B true RMS ac+dc current specifications 163
Ta b l e 7 - 8 Capacitance specifications 164
Ta b l e 7 - 9 Temperature specifications 164
Ta b l e 7 - 10 Frequency specifications 165
Ta b l e 7 - 11 Duty cycle and pulse width specifications 165
Ta b l e 7 - 12 Frequency sensitivity and trigger level specifications for
voltage measurements 166
Ta b l e 7 - 13 Frequency sensitivity specifications for current
measurements 167
Ta b l e 7 - 14 Peak hold specifications for dc voltage and current
measurements 168
Ta b l e 7 - 15 Frequency counter (divide by 1) specifications 168
Ta b l e 7 - 16 Frequency counter (divide by 100 [4])
specifications 169
Ta b l e 7 - 17 Square wave output specifications 169
Ta b l e 7 - 18 Display update rate (approximate) 171
Ta b l e 7 - 19 Input Impedance 172