Agilent Technologies U1251B Manual

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

2 Agilent U1251B/U1252B User’s and Service Guide
Notices
© Agilent Technologies, Inc. 2009
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
First Edition, December 01, 2009
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
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 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.

Agilent U1251B/U1252B User’s and Service Guide V
WARNING
• When working above 70V DC, 33 V AC 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 U1251B/U1252B User’s and Service Guide
CAUTION
•Turn off 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 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 U1251B/U1252B 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
Te c h n o l o g i e s, o r v i si t :
www.agilent.com/environment/product
for more information.

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 XI
Contents
1 Getting Started Tutorial 1
Introducing the Agilent U1251B and U1252B Handheld Digital
Multimeter 2
Adjusting the Tilt-Stand 3
The Front Panel at a Glance 5
The Rotary Switch at a Glance 6
The Keypad at a Glance 7
The Display at a Glance 9
Selection of Display by Hz Button 13
Selection of Display by Dual Button 15
Selection of Display by Shift Button 18
The Terminals at a Glance 20
The Rear Panel at a Glance 21
2 Making Measurements 23
Measuring Voltage 24
Measuring Current 27
Measuring DC voltage 26
Measuring Current 27
µA & mA Measurement 27
% Scale of 4–20 mA 28
A measurement 29
Frequency Counter 30
Measuring Resistance, Conductance and Testing Continuity 32
Tes t in g D io de s 36
Measuring Capacitance 39
Measuring Temperature 40
Alerts and Warning During Measurement 43
Overload Alert 43
Input Warning 43
Charge Terminal Alert 44

XII Agilent U1251B/U1252B User’s and Service Guide
Contents
3 Features and Functions 45
Dynamic Recording 46
Data Hold (Trigger Hold) 48
Refresh Hold 49
Null (Relative) 51
Decibel Display 53
1 ms Peak Hold 55
Data Logging 57
Manual Logging 57
Interval Logging 59
Reviewing Logged Data 61
Square Wave Output (for U1252B) 63
Remote Communication 67
4 Changing The Default Setting 69
Selecting Setup Mode 70
Setting Data Logging Mode 74
Setting Thermocouple Types (for U1252B) 75
Setting Reference Impedance for dBm Measurement 76
Setting Minimum Frequency Measurement 77
Setting Temperature Unit 78
Setting Auto Power Saving Mode 80
Setting % Scale Readout 82
Setting Beep Frequency 83
Setting Backlit Timer 84
Setting Baud Rate 85
Setting Parity Check 86
Setting Data Bit 87
Setting Echo Mode 88
Setting Print Mode 89
Returning to Default Factory Settings 90
Setting the Battery Voltage 91
Setting the DC Filter 92
5 Maintenance 93
Introduction 94
General Maintenance 94
Replacing the Battery 95
Charging the Battery 97

Contents
Agilent U1251B/U1252B User’s and Service Guide XIII
Replacing the Fuse 103
Troubleshooting 105
6 Performance Tests and Calibration 107
Calibration Overview 108
Closed-case Electronic Calibration 108
Agilent Technologies Calibration Services 108
Calibration Interval 108
Adjustment is Recommended 109
Recommended Test Equipment 110
Basic Operating Test 111
Backlit Test 111
Testing the Display 111
Current Terminal Test 112
C h ar g e Te r mi n a l A l e r t Te s t 113
Te s t C o n si d e r at i on s 114
Input Connections 115
Performance Verification Tests 116
Calibration Security 124
Unsecuring the Instrument for Calibration 125
Calibration Process 128
Using the Front Panel for Adjustments 129
Adjustments Consideration 130
Valid Adjustment Input Values 131
Adjustment Procedure 132
Finishing the Adjustment 139
To R e ad t h e C al i b ra ti o n C o un t 139
Calibration Errors 140
7 Specifications 141
DC Specifications 142
U1251B AC Specifications 144
U1252B AC Specifications 145
U1252B AC+DC Specifications 146
Temperature and Capacitance Specifications 147
U1251B & U1252B Frequency Specifications 148

XIV Agilent U1251B/U1252B User’s and Service Guide
Contents
Operating Specifications 152
General Specifications 154

1
Agilent U1251B and U1252B Handheld Digital Multimeter
User’s and Service Guide
Agilent Technologies
1
Getting Started Tutorial
Introducing the Agilent U1251B and U1252B Handheld Digital
Multimeter 2
Adjusting the Tilt-Stand 3
The Front Panel at a Glance 5
The Rotary Switch at a Glance 6
The Keypad at a Glance 7
The Display at a Glance 9
Selection of Display by Hz Button 13
Selection of Display by Dual Button 15
Selection of Display by Shift Button 18
The Terminals at a Glance 20
The Rear Panel at a Glance 21
This chapter contains a brief description of the front panel
of the Agilent U1251B and U1252B Handheld Digital
Multimeter.

2 Agilent U1251B/U1252B User’s and Service Guide
1 Getting Started Tutorial
Introducing the Agilent U1251B and U1252B Handheld Digital Multimeter
The handheld digital multimeter’s key features are:
•DC, AC and AC + DC (only U1252B) voltage and current
measurements.
•True- RMS measurement for both AC voltage and current
•Rechargeable Ni- MH battery with built- in charging
capability (only for U1252B)
•Ambient temperature on second display
•Battery capacity indicator
•Bright orange LED backlight
•Resistance measurement up to 50 M
Ω (for U1251B) and
500 M
Ω (for U1252B)
•Conductance measurement from 0.01 nS (100 G
Ω ) ~ 50 nS
•Capacitance measurement up to 100 mF
•Frequency counter up to 20 MHz (only U1252B)
• The % scale readout for 4- 20 mA or 0- 20 mA measurement
•dBm with selectable reference impedance
•1 ms Peak Hold to catch inrush voltage and current easily
•Temperature test with selectable 0 °C compensation
(without ambient temperature compensation).
•K- type (for U1251B) and J/K- types temperature
measurement (for U1252B)
•Frequency, duty cycle and pulse width measurements
•Dynamic Recording for min, max and average readings
•Data Hold with manual or auto trigger and Null mode
•Diode and audible continuity tests
•Square wave generator with selectable frequency, pulse
width and duty cycle (only U1252B)
•Agilent GUI Application Software (IR- USB cable sold
separately)
•Closed case calibration

Getting Started Tutorial 1
Agilent U1251B/U1252B User’s and Service Guide 3
•50,000 count precision true RMS digital multimeter,
designed to meet IEC61326- 1:2005 / EN61326- 1:2006
Category III 1000 V/ CAT IV 600 V Overvoltage Protection,
Pollution Degree II standards
Adjusting the Tilt-Stand
To adjust the meter to a 60°standing position, pull the
tilt- stand outwards to its maximum reach.
To adjust the meter to a 30°standing position, bend the tip
of the stand so that it is parallel to the ground before
pulling the stand outwards to its maximum reach.
To P C (ho s t)
Tilt-stand at 30 º
IR-USB cable
To P C ( h o st )
Tilt-stand at 60°
IR-USB cable

Getting Started Tutorial 1
Agilent U1251B/U1252B User’s and Service Guide 4
To adjust the meter to a hanging position, flip the stand
upwards and over its maximum reach until it is detached
from its hinge. Then flip the stand over so that the stand’s
inner surface is facing the meter’s rear. Now, press the stand
down into its hinge. Follow the step by step pictorial
instructions below.

Getting Started Tutorial 1
Agilent U1251B/U1252B User’s and Service Guide 5
The Front Panel at a Glance
Display
Keypad
Rotary switch
Display
Ter mina ls

6 Agilent U1251B/U1252B User’s and Service Guide
1 Getting Started Tutorial
The Rotary Switch at a Glance
Legend:
No. Description / Function
1 Charge mode [U1252B only] or OFF
2ACV
3 DC voltage or DC+AC voltage [U1252B only]
4 DC mV, AC mV, AC+DC mV [U1252B only]
5Resistance(
Ω ), Continuity, and Conductance ( nS )
6 Frequency counter [U1252B only] or Diode
7 Capacitance or Temperature
8 DC µA and AC µA
9 DC mA, DC current, AC mA or AC current
10 Square-wave output, Duty cycle or Pulse width output [for U1252B]
and OFF [for U1251B]
2
1
3
47
56
8
9
10