Page 1
Keysight U1241C/U1242C
Handheld Digital Multimeter
Service Guide
Page 2
Notices
CAUTION
WARNING
Copyright Notice
© Keysight Technologies 2016-2017
No part of this manual may be repro-
duced in any form or by any means
(including electronic storage and
retrieval or translation into a foreign
language) without prior agreement and
written consent from Keysight Technologies as governed by United States and
international copyright laws.
Manual Part Number
U1241-90104
Edition
Edition 5, April 21, 2017
Printed in:
Printed in Malaysia
Published by:
Keysight Technologies
Bayan Lepas Free Industrial Zone,
11900 Penang, Malaysia
Technology Licenses
The hardware and/or software
described in this document are furnished under a license and may be
used or copied only in accordance with
the terms of such license.
Declaration of Conformity
Declarations of Conformity for this
product and for other Keysight products may be downloaded from the
Web. Go to http://www.keysight.com/
go/conformity. You can then search by
product number to find the latest Declaration of Conformity.
U.S. Government Rights
The Software is “commercial computer
software,” as defined by Federal Acquisition Regulation (“FAR”) 2.101. Pursuant to FAR 12.212 and 27.405-3 and
Department of Defense FAR Supplement (“DFARS”) 227.7202, the U.S.
government acquires commercial computer software under the same terms
by which the software is customarily
provided to the public. Accordingly,
Keysight provides the Software to U.S.
government customers under its standard commercial license, which is
embodied in its End User License
Agreement (EULA), a copy of which can
be found at http://www.keysight.com/
find/sweula. The license set forth in the
EULA represents the exclusive authority
by which the U.S. government may use,
modify, distribute, or disclose the Software. The EULA and the license set
forth therein, does not require or permit, among other things, that Keysight:
(1) Furnish technical information
related to commercial computer software or commercial computer software
documentation that is not customarily
provided to the public; or (2) Relinquish
to, or otherwise provide, the government rights in excess of these rights
customarily provided to the public to
use, mod ify, reproduce, release, perform, display, or disclose commercial
computer software or commercial computer software documentation. No
additional government requirements
beyond those set forth in the EULA
shall apply, except to the extent that
those terms, rights, or licenses are
explicitly required from all providers of
commercial computer software pursuant to the FAR and the DFARS and are
set forth specifically in writing elsewhere in the EULA. Keysight shall be
under no obligation to update, revise or
otherwise modify the Software. With
respect to any technical data as
defined by FAR 2.101, pursuant to FAR
12.211 and 27.404.2 and DFARS
227.7102, the U.S. government
acquires no greater than Limited Rights
as defined in FAR 27.401 or DFAR
227.7103-5 (c), as applicable in any
technical data.
Warranty
THE MATERIAL CONTAINED IN THIS
DOCUMENT IS PROVIDED “AS IS,”
AND IS SUBJECT TO BEING
CHANGED, WITHOUT NOTICE, IN
FUTURE EDITIONS. FURTHER, TO THE
MAXIMUM EXTENT PERMITTED BY
APPLICABLE LAW, KEYSIGHT 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
PARTICULAR PURPOSE. KEYSIGHT
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 KEYSIGHT
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.
Safety Information
A CAUTION notice denotes a hazard. It
calls attention to an operating 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.
A WARNING notice denotes a hazard. It
calls attention to an operating procedure, practice, or the like that, if not
correctly performed or adhered to,
could result in personal injury or death.
Do not proceed beyond a WARNING
notice until the indicated conditions are
fully understood and met.
2 Keysight U1241C/U1242C Service Guide
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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.
Caution, risk of danger (refer to this
manual for specific Warning or Caution
information)
Earth (ground) terminal
CAT IV
600 V
Equipment protected throughout by
double insulation or reinforced
insulation
Category IV 600 V overvoltage
protection
CAT III
1000 V
Category III 1000 V overvoltage
protection
Keysight U1241C/U1242C Service Guide 3
Page 4
Safety Considerations
WARNING
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. Keysight
Technologies assumes no liability for the customer’s failure to comply with these
requirements.
– Do not exceed any of the measurement limits defined in the specifications
to avoid instrument damage and the risk of electric shock.
– 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 mul timeter)
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.
– 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.
4 Keysight U1241C/U1242C Service Guide
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WARNING
– When using the probes, keep your fingers behind the finger guards on the
CAUTION
probes.
– Only use the probe assemblies with RATED MEASUREMENT CATEGORY III
or IV for MAINS measurements.
– 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.
– Remove the test leads from the measuring source or target before
changing the rotary switch position.
– 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.
– Comply with local and national safety requirements when working in
hazardous areas, and use proper protection equipment.
– Disconnect circuit power and discharge all high-voltage capacitors
before testing resistance, continuity, diodes, or capacitance.
Keysight U1241C/U1242C Service Guide 5
– Use the proper terminals, function, and range for your measurements.
– This multimeter is for use at altitudes of up to 3000 m.
– Never measure voltage when the current measurement is selected.
– Always use the specified battery type. The power for the multimeter is
supplied by four 1.5 V AAA batteries. Observe the correct polarity
markings before you insert the batteries to ensure proper insertion of the
batteries in the multimeter.
– To prevent damage to the multimeter from battery leakage:
– Always remove dead batteries immediately.
– Always remove the batteries and store them separately if the multimeter
is not going to be used for a long period.
Page 6
Measurement Category
The U1241C/U1242C has safety ratings of CAT III 1000 V and CAT IV 600 V.
Measurement CAT I Measurements performed on circuits not directly
connected to the AC mains. Examples are measurements on circuits not derived
from the AC mains and specially protected (internal) mains-derived circuits.
Measurement CAT II Measurements performed on circuits directly connected to
a low-voltage installation. Examples are measurements on household appliances,
portable tools, and similar equipment.
Measurement CAT III Measurements performed in the building installation.
Examples are measurements on distribution boards, circuit-breakers, wiring,
including cables, bus-bars, junction boxes, switches, socket outlets in the fixed
installation, and equipment for industrial use, and some other equipment
including stationary motors with permanent connection to the fixed installation.
Measurement CAT IV Measurements performed at the source of the
low-voltage installation. Examples are electricity meters and measurements on
primary overcurrent protection devices and ripple control units.
Use only the product rated Measurement Category on the location of measuring
circuits as identified below.
6 Keysight U1241C/U1242C Service Guide
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Environmental Conditions
The U1241C/U1242C is designed for indoor use and in an area with low
condensation. The table below shows the general environmental requirements for
this instrument.
Environmental condition Requirement
Temperature
Humidity
Altitude Up to 3000 m
Pollution degree 2
Operating condition
– –20 °C to 55 °C, 0 to 80% RH
Storage condition
– –40 °C to 70 °C, 0 to 80% RH (without batteries)
Up to 80% RH for temperature of up to 30 °C decreasing
linearly to 50% RH at 55 °C
Keysight U1241C/U1242C Service Guide 7
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Safety and Regulatory Information
The U1241C/U1242C complies with the following safety and Electromagnetic
Compatibility (EMC) compliances:
Safety compliance
– IEC/EN 61010-1
– IEC/EN 61010-2-033
– Canada: CAN/CSA-C22.2 No. 61010-1, CAN/CSA-C22.2 No. 61010-033
– USA: ANSI/UL Std. No. 61010-1, ANSI/UL Std. No. 61010-033
EMC compliance
– IEC 61326-1/EN 61326-1
– Canada: ICES/NMB-001
– Australia/New Zealand: AS/NZS CISPR 11
8 Keysight U1241C/U1242C Service Guide
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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.
ICES/NMB-001 indicates that this ISM
device complies with the Canadian
ICES-001.
Cet appareil ISM est conforme 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.
This symbol is a South Korean Class A
EMC Declaration. This is a Class A
instrument suitable for professional
use and in electromagnetic
environment outside of the home.
The CSA mark is a registered
trademark of the Canadian Standards
Association.
The RCM mark is a registered
trademark of the Australian
Communications and Media Authority.
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.
Keysight U1241C/U1242C Service Guide 9
Page 10
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 Keysight Service Center,
or visit http://about.keysight.com/en/companyinfo/environment/takeback.shtml
for more information.
Sales and Technical Support
To contact Keysight for sales and technical support, refer to the support links on
the following Keysight websites:
– www.keysight.com/find/U1241C or www.keysight.com/find/U1242C
(product-specific information and support, software and
documentation updates)
– www.keysight.com/find/assist
(worldwide contact information for repair and service)
10 Keysight U1241C/U1242C Service Guide
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Table of Contents
Safety Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Measurement Category . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Environmental Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Safety and Regulatory Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Regulatory Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Waste Electrical and Electronic Equipment (WEEE) Directive 2002/96/
EC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Product category . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Sales and Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
1 Calibration Procedures
Calibration Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Closed-case calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Keysight calibration services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Calibration interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Recommended adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Recommended Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Basic Operating Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Backlight test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Display test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Input warning test (A terminal) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Input warning test ( terminal) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Calibration Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Test Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Performance Verification Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Calibration Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Unsecuring the Multimeter for Calibration . . . . . . . . . . . . . . . . . . . . . .35
To unsecure the multimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
To change the calibration security code . . . . . . . . . . . . . . . . . . . . . .38
Keysight U1241C/U1242C Service Guide 11
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To reset the calibration security code to its factory default . . . . . . . 40
Using the Front Panel for Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . 42
Adjustment considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Rotary switch position for calibration . . . . . . . . . . . . . . . . . . . . . . . . 43
Valid adjustment input values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Vsense (non-contact voltage) calibration . . . . . . . . . . . . . . . . . . . . . 47
Adjustment procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Exiting the adjustment mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Calibration Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Calibration Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
2Service and Maintenance
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Fuse Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Returning the Multimeter for Service . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Replaceable Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
To order replaceable parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Types of Service Available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Extended service contracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Obtaining Repair Service (Worldwide) . . . . . . . . . . . . . . . . . . . . . . . . . . 62
12 Keysight U1241C/U1242C Service Guide
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List of Figures
Figure 1-1 Display screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Figure 1-2 Example of A-Er for wrong terminal input . . . . . . . . . .22
Figure 1-3 Example of μAEr for wrong terminal input . . . . . . . . .23
Figure 1-4 Calibration security code . . . . . . . . . . . . . . . . . . . . . . .35
Figure 1-5 Unsecuring the multimeter . . . . . . . . . . . . . . . . . . . . .37
Figure 1-6 Changing the calibration security code . . . . . . . . . . . . 39
Figure 1-7 Resetting the calibration security code to its factory
Figure 1-8 Rotary switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Figure 1-9 Vsense (non-contact voltage) calibration . . . . . . . . . .49
Figure 1-10 Calibration count mode . . . . . . . . . . . . . . . . . . . . . . . .53
default . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
Keysight U1241C/U1242C Service Guide 13
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List of Tables
Table 1-1 Recommended test equipment . . . . . . . . . . . . . . . . . . 20
Table 1-2 Z
Table 1-3 DC V (V) performance verification tests . . . . . . . . . . . .26
Table 1-4 AC V (V) true rms performance verification tests . . . . 27
Table 1-5 AC V (V) averaging sense performance verification tests
Table 1-6 DC current (μA.mA) performance verification tests . .29
Table 1-7 AC current (A) true rms performance verification tests .
Table 1-8 AC current (A) averaging sense performance verification
Table 1-9 Diode performance verification test . . . . . . . . . . . . . . .31
Table 1-10 Capacitance performance verification tests . . . . . . . .32
Table 1-11 Resistance performance verification tests . . . . . . . . . .32
Table 1-12 Frequency performance verification tests . . . . . . . . . . 33
Table 1-13 Temperature performance verification test . . . . . . . . .33
Table 1-14 Rotary switch positions for calibration . . . . . . . . . . . .43
Table 1-15 Adjustment input values . . . . . . . . . . . . . . . . . . . . . . . 44
Table 1-16 Calibration error codes . . . . . . . . . . . . . . . . . . . . . . . . .54
Table 2-1 Operating checklist . . . . . . . . . . . . . . . . . . . . . . . . . . .56
(DC V) performance verification tests . . . . . . . .25
LOW
28
30
tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Keysight U1241C/U1242C Service Guide 15
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16 Keysight U1241C/U1242C Service Guide
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Keysight U1241C/U1242C Handheld Digital Multimeter
Service Guide
1 Calibration Procedures
Calibration Overview 18
Recommended Test Equipment 20
Basic Operating Tests 21
Calibration Process 24
Test Considerations 24
Performance Verification Tests 25
Calibration Security 34
Unsecuring the Multimeter for Calibration 35
Using the Front Panel for Adjustments 42
Calibration Count 52
Calibration Error Codes 54
This chapter helps you to verify the multimeter’s performance and to make
adjustments where necessary.
17
Page 18
1 Calibration Procedures
NOTE
Calibration Overview
This manual contains procedures to verify the performance of the U1241C/
U1242C handheld digital multimeter and to perform adjustments (calibration).
The performance test procedures allow you to verify that the multimeter is
operating within its published specifications. The adjustment procedures ensure
that the multimeter remains within its specifications until the next calibration.
Ensure that you have read the “Test Considerations” on page 24 before
calibrating the multimeter.
Closed-case calibration
The multimeter features closed-case electronic calibration. In other words, no
internal mechanical adjustments are required. The multimeter calculates
correction factors based upon the input reference value you set. The new
correction factors are stored in the nonvolatile memory until the next calibration
adjustment is performed. The nonvolatile EEPROM calibration memory is retained
even when power is switched off.
Keysight calibration services
When your multimeter is due for calibration, contact your local Keysight Service
Center to enquire about recalibration services.
Calibration interval
A 1-year interval is adequate for most applications. Accuracy specifications are
warranted only if adjustment is made at regular calibration intervals. A 1-year
calibration cycle is suggested for operation at room temperature. The calibration
cycle is 1.5 times of accuracy for 2 years except for capacitance and frequency
measurements. Keysight does not recommend extending calibration intervals
beyond 2 years for any application.
18 Keysight U1241C/U1242C Service Guide
Page 19
Recommended adjustment
Specifications are only guaranteed within the period stated from the last
adjustment. Keysight recommends that re-adjustment should be performed
during the calibration process for best performance. This will ensure that the
multimeter will remain within the specifications for the next calibration interval.
This criterion for the re-adjustment provides the best long-term stability.
Performance data are measured during the “Performance Verification Tests” on
page 25 but this does not guarantee that the multimeter will remain within these
limits unless the adjustments are performed.
See “Calibration Count” on page 52 and verify that all the adjustments have been
performed.
Calibration Procedures 1
Keysight U1241C/U1242C Service Guide 19
Page 20
1 Calibration Procedures
Recommended Test Equipment
The test equipment recommended for the performance verification and
adjustment procedures are listed below (Tab le 1-1). If the exact instrument is not
available, substitute with another calibration standard of equivalent accuracy.
A suggested alternative method is to use the Keysight 3458A 8½-Digit Digital
Multimeter to measure less accurate but stable sources. The output value
measured from the source can be entered into the instrument as the target
calibration value.
Tab le 1-1 Recommended test equipment
Application Recommended equipment Recommended accuracy requirement
DC voltage Fluke 5520A/5522A <20% of the instrument’s 1-year specifications
AC true rms voltage Fluke 5520A/5522A <20% of the instrument’s 1-year specifications
AC averaging sense
voltage
DC current Fluke 5520A/5522A <20% of the instrument’s 1-year specifications
AC true rms current Fluke 5520A/5522A <20% of the instrument’s 1-year specifications
AC average current Fluke 5520A/5522A <20% of the instrument’s 1-year specifications
Fluke 5520A/5522A <20% of the instrument’s 1-year specifications
Diode Fluke 5520A/5522A <20% of the instrument’s 1-year specifications
Capacitance Fluke 5520A/5522A <20% of the instrument’s 1-year specifications
Resistance Fluke 5520A/5522A <20% of the instrument’s 1-year specifications
Frequency Fluke 5520A/5522A <20% of the instrument’s 1-year specifications
Fluke 5520A/5522A <20% of the instrument’s 1-year specifications
Temperature
TM Electronics KMPC1MP
(K-Type thermocouple extension)
—
20 Keysight U1241C/U1242C Service Guide
Page 21
Basic Operating Tests
Hold
Log
The basic operating tests are used to test the basic operability of the multimeter.
Repair is required if the multimeter fails the basic operating tests.
Backlight test
Press to test the backlight. It will momentarily toggle the backlight on and
off.
Display test
Press and turn on the multimeter to view all annunciators of the display.
Compare the display with the example in Figure 1-1.
Calibration Procedures 1
Figure 1-1 Display screen
Keysight U1241C/U1242C Service Guide 21
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1 Calibration Procedures
21
Vsense
1
U1242C
True RMS Multimeter
mA
A
COM
V
A
V
V
mA
Z
LOW
Hz
Range
Shift
Hold
Esc
Vsense
MaxMin
Auto
Log
View
2
600V
CAT III 1000V
CAT IV
MAX
FUSED
10A MAX FUSED
440mA
NOTE
Input warning test (A terminal)
This test determines if the input warning of the current terminal test is
functioning properly. The multimeter emits a continuous beep and the red LED
indicator lights up when the test lead is inserted into the input terminal but the
rotary switch is not set to the corresponding position. The secondary display
will show until the test lead is removed from the input terminal or until
the rotary switch is set to the position.
Figure 1-2 Example of A-Er for wrong terminal input
Before conducting this test, make sure the beep alert function is enabled in the
Setup mode.
22 Keysight U1241C/U1242C Service Guide
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Input warning test ( terminal)
mA
mA
21
Vsense
1
U1242C
True RMS Multimeter
mA
A
COM
V
A
V
V
mA
Z
LOW
Hz
Range
Shift
Hold
Esc
Vsense
MaxMin
Auto
Log
View
2
600V
CAT III 1000V
CAT IV
MAX
FUSED
10A MAX FUSED
440mA
NOTE
The multimeter emits a continuous beep and the red LED indicator lights up when
the test lead is inserted into the input terminal but the rotary switch is not
set to the corresponding function. The secondary display will show
until the test lead is removed from the input terminal or until the rotary
switch is set to the position.
Calibration Procedures 1
Figure 1-3 Example of μAEr for wrong terminal input
Before conducting this test, make sure the beep alert function is enabled in the
Setup mode.
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1 Calibration Procedures
Calibration Process
1 Prior to performing the verification tests, see the “Test Considerations” on
page 24.
2 Perform the verification tests to characterize the multimeter; see “Performance
Verification Tests” on page 25.
3 Unsecure the multimeter for calibration; see “Calibration Security” on page 34.
4 Prior to performing the adjustments, see the “Adjustment considerations” on
page 42.
5 Perform the adjustment procedure; see “Adjustment procedure” on page 50.
6 Secure the multimeter against unauthorized calibration; see “Exiting the
adjustment mode” on page 51. Ensure that the multimeter has quit the
adjustment mode and is turned off.
7 Record the new security code and calibration.
Test Considerations
For optimum performance, all procedures should comply with the following
recommendations:
– The performance verification test or adjustment should be performed under
laboratory conditions where the ambient temperature can be controlled.
– The multimeter should be put under the laboratory environment for at least
1 hour.
– Ensure that the calibration ambient temperature is stable and is between 18 °C
and 28 °C. Ideally the calibration should be performed at 23 °C ± 1 °C.
– Ensure that the ambient relative humidity is less than 80%.
– Allow a warm-up period of 5 minutes.
– Use a shielded twisted pair of PTFE-insulated cables to reduce settling and
noise errors. Keep the input cables as short as possible. Long test leads can
also act as antennas which may pick up AC signals.
– Connect the input cable shields to earth ground.
24 Keysight U1241C/U1242C Service Guide
Page 25
Performance Verification Tests
NOTE
Z
LOW
Shift
Esc
View
Z
LOW
Use the performance verification tests to verify the measurement performance of
the multimeter. The performance verification tests use the multimeter’s
specifications listed in the U1241C/U1242C datasheet
(http://literature.cdn.keysight.com/litweb/pdf/5992-0848EN.pdf).
The performance verification tests are recommended as acceptance tests when
you first receive the multimeter. The acceptance test results should be compared
against the 1-year test limits. After acceptance, you should repeat the
performance verification tests at every calibration interval.
If the multimeter fails the performance verification tests, adjustment or repair is
required.
Ensure that you have read the “Test Considerations” on page 24 before running
the performance verification tests.
Calibration Procedures 1
Table 1-2 Z
Test function Range
(DC V)
[a]
Z
LOW
Turn the rotary switch to the position and press
(DC V) performance verification tests
LOW
1000 V 30 V N/A ±0.7 V
5520A/5522A
output
Error from nominal 1 year
U1241C U1242C
.
(Input impedance)
Z
LOW
[a]
1000 V 1.8 kΩ N/A ±0.180 kΩ
Turn the rotary switch to the position.
[a] Functional test only.
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1 Calibration Procedures
21
V
Tab le 1-3 DC V (V) performance verification tests
Test function Range
DC mV (mV)
Turn the rotary switch to the position.
100 mV
600 mV
[a][b]
[a][b]
5520A/5522A
output
100 mV ±0.11 V ±0.11 V
600 mV ±0.7 V ±0.7 V
Error from nominal 1 year
U1241C U1242C
1000 mV 1000 mV ±1.1 V ±1.1 V
DC V (V)
Turn the rotary switch to the position.
10 V 10 V ±0.011 V ±0.011 V
100 V 100 V ±0.11 V ±0.11 V
1000 V 1000 V ±1.1 V ±1.1 V
[a] The impedance may be set to >1 GΩ from the Setup mode; the default value is 10 MΩ in parallel with 100 pF (nominal). The accuracy of DC
mV is specified after the Null function is used to subtract the thermal effect (by shorting the test leads) before measuring the signal.
[b] Before turning the rotary switch, you must enable the mV measurement function from the Setup menu first. For enabling the mV
measurement function from the Setup menu, refer to the U1241C/U1242C User’s Guide.
26 Keysight U1241C/U1242C Service Guide
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Table 1-4 AC V (V) true rms performance verification tests
21
V
Calibration Procedures 1
Test function Range
100 mV
AC mV (mV) true rms
Turn the rotary switch to the position.
600 mV
1000 mV
10 V
AC V (V) true rms
Turn the rotary switch to the position.
100 V
1000 V
[a][b]
[a][b]
5520A/5522A
output
Error from nominal 1 year
U1241C U1242C
100 mV, 40 Hz ±1.03 mV ±1.03 mV
100 mV, 1 kHz ±1.03 mV ±1.03 mV
100 mV, 2 kHz ±1.53 mV ±1.53 mV
600 mV, 40 Hz ±6.3 mV ±6.3 mV
600 mV, 1 kHz ±6.3 mV ±6.3 mV
600 mV, 2 kHz ±9.3 mV ±9.3 mV
1000 mV, 40 Hz ±10.3 mV ±10.3 mV
1000 mV, 1 kHz ±10.3 mV ±10.3 mV
1000 mV, 2 kHz ±15.3 mV ±15.3 mV
10 V, 40 Hz ±0.103 V ±0.103 V
10 V, 1 kHz ±0.103 V ±0.103 V
10 V, 2 kHz ±0.153 V ±0.153 V
100 V, 45 Hz ±1.03 V ±1.03 V
100 V, 1 kHz ±1.03 V ±1.03 V
100 V, 2 kHz ±1.53 V ±1.53 V
1000 V, 45 Hz ±10.3 V ±10.3 V
1000 V, 1 kHz ±10.3 V ±10.3 V
1000 V, 2 kHz ±15.3 V ±15.3 V
[a] The impedance may be set to >1 GΩ from the Setup mode; the default value is 10 MΩ in parallel with 100 pF (nominal).
[b] Before turning the rotary switch, you must enable the mV measurement function from the Setup menu first. For enabling the mV
measurement function from the Setup menu, refer to the U1241C/U1242C User’s Guide.
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1 Calibration Procedures
21
V
Shift
Esc
View
Tab le 1-5 AC V (V) averaging sense performance verification tests
Test function Range
100 mV
AC mV (mV) averaging sense
Turn the rotary switch to the position.
600 mV
1000 mV
AC V (V) averaging sense
10 V
Turn the rotary switch to the position and press
.
100 V
[a][b]
[a][b]
5520A/5522A
output
100 mV, 40 Hz
100 mV, 1 kHz ±1.05 mV
Error from nominal 1 year
U1241C U1242C
±1.05 mV
N/A
100 mV, 2 kHz ±1.55 mV
600 mV, 40 Hz
600 mV, 1 kHz ±6.5 mV
N/A
±6.5 mV
600 mV, 2 kHz ±9.5 mV
1000 mV, 40 Hz
1000 mV, 1 kHz ±10.5 mV
N/A
±10.5 mV
1000 mV, 2 kHz ±15.5 mV
10 V, 40 Hz
10 V, 1 kHz ±0.105 V
N/A
±0.105 V
10 V, 2 kHz ±0.155 V
100 V, 45 Hz
100 V, 1 kHz ±1.05 V
N/A
±1.05 V
100 V, 2 kHz ±1.55 V
1000 V, 45 Hz
±10.5 V
1000 V
1000 V, 1 kHz ±10.5 V
N/A
1000 V, 2 kHz ±15.5 V
[a] The impedance may be set to >1 GΩ from the Setup mode; the default value is 10 MΩ in parallel with 100 pF (nominal).
[b] Before turning the rotary switch, you must enable the mV measurement function from the Setup menu first. For enabling the mV
measurement function from the Setup menu, refer to the U1241C/U1242C User’s Guide.
28 Keysight U1241C/U1242C Service Guide
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Table 1-6 DC current (μA.mA) performance verification tests
mA
CAUTION
Calibration Procedures 1
Test function Range
1000 μA 1000 μA ±1.2 μA±1.2 μA
DC current (μA.mA)
Turn the rotary switch to the position.
[a] 440 mA continuous, and the signal greater than 440 mA ~ 600 mA for 20 hours maximum. After measuring current of >440 mA, cool down the
multimeter for the same measuring time you applied before performing low current measurement.
[b] 10 A continuous, and the signal greater than 10 A ~ 19.999 A for 30 seconds maximum. After measuring current of >10 A, cool down the
multimeter for the same measuring time you applied before performing low current measurement.
10 mA 10 mA ±0.012 mA ±0.012 mA
100 mA 100 mA ±0.22 mA ±0.22 mA
[a]
440 mA
[b]
10 A
5520A/5522A
output
440 mA ±1.1 mA ±1.1 mA
10 A ±0.035 A ±0.035 A
Error from nominal 1 year
U1241C U1242C
Connect the calibrator outputs to the mul timeter’s A and COM terminals
before applying 10 A.
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1 Calibration Procedures
A
Shift
Esc
View
CAUTION
Tab le 1-7 AC current (A) true rms performance verification tests
Test function Range
5520A/5522A
output
Error from nominal 1 year
U1241C U1242C
1000 μA, 40 Hz ±10.3 μA ±10.3 μA
1000 μA
1000 μA, 1 kHz ±10.3 μA ±10.3 μA
10 mA, 40 Hz ±0.103 mA ±0.103 mA
AC current (A) true rms
Turn the rotary switch to the position and press
10 mA
10 mA, 1 kHz ±0.103 mA ±0.103 mA
100 mA, 40 Hz ±1.03 mA ±1.03 mA
100 mA
100 mA, 1 kHz ±1.03 mA ±1.03 mA
.
[a]
440 mA
[b]
10 A
[a] 440 mA continuous, and the signal greater than 440 mA ~ 600 mA for 20 hours maximum. After measuring current of >440 mA, cool down the
multimeter for the same measuring time you applied before performing low current measurement.
[b] 10 A continuous, and the signal greater than 10 A ~ 19.999 A for 30 seconds maximum. After measuring current of >10 A, cool down the
multimeter for the same measuring time you applied before performing low current measurement.
440 mA, 40 Hz ±4.7 mA ±4.7 mA
440 mA, 1 kHz ±4.7 mA ±4.7 mA
10 A, 45 Hz ±0.125 A ±0.125 A
10 A, 1 kHz ±0.125 A ±0.125 A
Connect the calibrator outputs to the multimeter’s A and COM terminals
before applying 10 A.
30 Keysight U1241C/U1242C Service Guide
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Calibration Procedures 1
A
Shift
Esc
View
CAUTION
Table 1-8 AC current (A) averaging sense performance verification tests
Test function Range
1000 μA
5520A/5522A
output
1000 μA, 40 Hz
Error from nominal 1 year
U1241C U1242C
±12.5 μA
N/A
1000 μA, 1 kHz ±12.5 μA
AC current (A) averaging sense
Turn the rotary switch to the position and press
10 mA
100 mA
10 mA, 40 Hz
N/A
10 mA, 1 kHz ±0.125 mA
100 mA, 40 Hz
N/A
±0.125 mA
±1.25 mA
100 mA, 1 kHz ±1.25 mA
twice.
[a]
440 mA
[b]
10 A
[a] 440 mA continuous, and the signal greater than 440 mA ~ 600 mA for 20 hours maximum. After measuring current of >440 mA, cool down the
multimeter for the same measuring time you applied before performing low current measurement.
[b] 10 A continuous, and the signal greater than 10 A ~ 19.999 A for 30 seconds maximum. After measuring current of >10 A, cool down the
multimeter for the same measuring time you applied before performing low current measurement.
440 mA, 40 Hz
±5.8 mA
N/A
440 mA, 1 kHz ±5.8 mA
10 A, 45 Hz
±0.125 A
N/A
10 A, 1 kHz ±0.125 A
Connect the calibrator outputs to the mul timeter’s A and COM terminals
before applying 10 A.
Table 1-9 Diode performance verification test
Test function Range
Diode
Turn the rotary switch to the position.
2 V 2 V ±0.020 V ±0.020 V
5520A/5522A
output
Error from nominal 1 year
U1241C U1242C
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1 Calibration Procedures
Shift
Esc
View
Table 1-10 Capacitance performance verification tests
Test function Range
1000 nF 1000 nF ±10.5 nF ±10.5 nF
Capacitance
Turn the rotary switch to the position and press
.
10 μF10 μF ±0.105 μF ±0.105 μF
100 μF100 μF ±1.05 μF±1.05 μF
1000 μF 1000 μF ±12.5 μF ±12.5 μF
10 mF 10 mF ±0.125 mF ±0.125 mF
Table 1-11 Resistance performance verification tests
Test function Range
[a]
1000 Ω
10 kΩ 10 kΩ ±0.022 kΩ ±0.022 kΩ
Resistance
Turn the rotary switch to the position.
100 kΩ 100 kΩ ±0.22 kΩ ±0.22 kΩ
1000 kΩ 1000 kΩ ±2.2 kΩ ±2.2 kΩ
10 MΩ 10 MΩ ±0.082 MΩ ±0.082 MΩ
100 MΩ
5520A/5522A
output
5520A/5522A
output
Error from nominal 1 year
U1241C U1242C
Error from nominal 1 year
U1241C U1242C
1000 Ω ±2.2 Ω ±2.2 Ω
25 MΩ ±0.41 MΩ ±0.41 MΩ
100 MΩ ±3.03 MΩ ±3.03 MΩ
[a] The accuracy of the 1000 Ω range is specified after Math Null, which is used to subtract the test lead resistance and the thermal effect.
32 Keysight U1241C/U1242C Service Guide
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Table 1-12 Frequency performance verification tests
V
Hz
MaxMin
21
NOTE
Calibration Procedures 1
Test function Range
Frequency
While the rotary switch is at the position, press
.
[a] The frequency measurement is susceptible to errors when measuring low-voltage, low-frequency signals. Shielding inputs from external
noise pickup is critical for minimizing measurement errors.
100 Hz
[a]
5520A/5522A
output
100 Hz, 1 V ±0.03 Hz ±0.03 Hz
Error from nominal 1 year
U1241C U1242C
Table 1-13 Temperature performance verification test
Test function Range
Temperature
Turn the rotary switch to the position.
–200 °C to 1372 °C 0 °C ±1 °C ±1 °C
5520A/5522A
output
Error from nominal 1 year
U1241C U1242C
– Set both Fluke 5520A and multimeter to internal reference.
– Prior to performing measurements, connect one end of the K-type
thermocouple (with miniature TC connector on both ends) to the 5520A TC
output, and the other end to a precision thermometer to verify that the source
outputs the desired value. Adjust the source accordingly if necessary.
– To perform the measurement, connect one end of the K-type thermocouple
(with miniature TC connector on both ends) to the 5520A TC output, and the
other end to the multimeter via a TC-to-banana adapter. Allow at least
1 hour for the multimeter to stabilize.
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1 Calibration Procedures
NOTE
Calibration Security
The calibration security code prevents accidental or unauthorized adjustments to
the multimeter. When you first receive your multimeter, it is secured.
Before you can adjust the multimeter, you must unsecure it by entering the
correct security code. See “Unsecuring the Multimeter for Calibration” on
page 35.
The security code can only be changed after the multimeter has been
unsecured. You can unsecure the multimeter from its front panel.
The security code is set to when the multimeter is shipped from the factory.
The security code is stored in nonvolatile memory, and does not change when
power has been turned off or after a remote interface reset. The security code may
contain up to four numeric characters.
34 Keysight U1241C/U1242C Service Guide
Page 35
Unsecuring the Multimeter for Calibration
NOTE
Hold
Log
Shift
Esc
View
Hz
MaxMin
Range
Auto
Vsense
Before you can adjust the multimeter, you must unsecure it by entering the
correct security code. The default security code is set to .
If you forget your security code, see “To reset the calibration security code to its
factory default” on page 40.
To unsecure the multimeter
1 During normal operation mode, press both and together for
more than 1 second to enter unsecured mode.
The calibration security code entry is shown on the display.
Calibration Procedures 1
Figure 1-4 Calibration security code
2 Enter the default security code to unsecure the multimeter.
– Press or to move the cursor to the left or right
respectively.
– Press or to increment or decrement the digit respectively.
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1 Calibration Procedures
Hold
Log
Hold
Log
Shift
Esc
View
3 When completed, press .
– If the correct security code is entered, will appear briefly, after which
the multimeter will enter the adjustment mode.
– If the incorrect security code is entered, an error code will appear briefly,
after which the multimeter will prompt you for the security code again.
4 Exit the unsecured mode by pressing both and together for
more than 1 second to secure the multimeter again.
See Figure 1-5 for the multimeter’s display.
36 Keysight U1241C/U1242C Service Guide
Page 37
Press and for >1 sec.
Hold
Log
Shift
Esc
View
Press , , , and
to enter the values.
Hz
MaxMin
Range
Auto
Vsense
After appearing
briefly
Pass
Press to confirm.
Hold
Log
Fail
After appearing
briefly
Calibration Procedures 1
Keysight U1241C/U1242C Service Guide 37
Figure 1-5 Unsecuring the multimeter
Page 38
1 Calibration Procedures
Shift
Esc
View
Hz
MaxMin
Range
Auto
Vsense
Hold
Log
Shift
Esc
View
Hold
Log
Shift
Esc
View
To change the calibration security code
This feature allows you to enter a security code to prevent accidental or
unauthorized calibration of the multimeter. The multimeter will be secured
automatically after power off. Ensure you unsecure the multimeter by entering the
correct security code before you adjust or calibrate the multimeter.
1 Press for more than 1 second to enter the Changing Security Code
(CSC) mode while the multimeter is unsecured (rEF mode). will be shown
as the existing security code.
2 Set your new calibration security code by entering any four digits ranging from
– Press or to move the cursor to the left or right
respectively.
– Press or to increment or decrement the digit respectively.
to .
3 Press to save the new calibration security code.
If the new calibration security code has been successfully changed, will
appear briefly, after which the multimeter will enter the adjustment mode.
If the incorrect security code is entered, an error code will appear briefly, after
which the multimeter will prompt you for the security code again.
4 Press for more than 1 second again if you wish to discard the change.
5 Record down your new calibration security code and store it in a safe location.
6 Exit the unsecured mode by pressing both and together for
more than 1 second to secure the multimeter again.
See Figure 1-6 for the multimeter’s display.
38 Keysight U1241C/U1242C Service Guide
Page 39
Press for >1 sec.
Shift
Esc
View
Press , , , and
to enter the values.
Hz
MaxMin
Range
Auto
Vsense
After appearing
briefly
Pass
Press to confirm.
Hold
Log
Fail
After appearing
briefly
Calibration Procedures 1
Keysight U1241C/U1242C Service Guide 39
Figure 1-6 Changing the calibration security code
Page 40
1 Calibration Procedures
NOTE
Hold
Log
Shift
Esc
View
Shift
Esc
View
Hz
MaxMin
Range
Auto
Vsense
Hold
Log
To reset the calibration security code to its factory default
If you have forgotten the correct calibration security code, you may follow the
steps below to reset the calibration security code to the factory default code,
.
If you do not have a record (or have lost the record) of the security code, first try
the factory default code, .
1 Note down the last four digits of the multimeter’s serial number (located at the
bottom of the rear panel) before you begin.
2 Press both and together for more than 1 second during
normal operation mode to enter unsecured mode. will be displayed.
3 Press for more than 1 second to enter the Default Security Code
(dSC) mode.
4 Enter the last four digits of the multimeter’s serial number.
– Press or to move the cursor to the left or right
respectively.
– Press or to increment or decrement the digit respectively.
5 Press to confirm your entry.
– If the four digits entered are correct, the display will show briefly.
The calibration security code is now set to its factory default code, .
– If the incorrect security code is entered, an error code will appear briefly,
after which the multimeter will prompt you for the security code again.
– To enter a new security code, see “To change the calibration security code”
on page 38. Ensure that you record down the new security code.
See Figure 1-7 for the multimeter’s display.
40 Keysight U1241C/U1242C Service Guide
Page 41
Press , , , and
to enter the values.
Hz
MaxMin
Range
Auto
Vsense
After appearing
briefly
Pass
Press to confirm.
Hold
Log
Fail
After appearing
briefly
Press for >1 sec.
Shift
Esc
View
Calibration Procedures 1
Keysight U1241C/U1242C Service Guide 41
Figure 1-7 Resetting the calibration security code to its factory default
Page 42
1 Calibration Procedures
NOTE
CAUTION
Using the Front Panel for Adjustments
This section describes the procedures to perform adjustments from the front
panel.
To unsecure the multimeter, see “To unsecure the multimeter” on page 35. Once
unsecured, the reference value will be indicated on the display.
Adjustment considerations
– Ensure you are qualified to perform the adjustments.
– Ensure the battery capacity is greater than the indicated 60%.
– Ensure that the environmental temperature is 23 ºC ± 2 ºC and the relative
humidity is <50%.
– Consider the thermal effects as you are connecting the test leads to the
calibrator and multimeter. It is recommended to wait for 3 to 5 seconds before
you begin the calibration after connecting the test leads.
– Do not turn off the multimeter during calibration. This may cause all
calibration memory to be lost. Ensure that you quit the calibration mode before
turning off the multimeter.
– Calibrate the DC mV prior to ambient temperature calibration. Do not calibrate
the DC mV immediately after a high current measurement or calibration.
– Turn on the multimeter for at least 1 hour with the K-type thermocouple
connected before proceeding with the ambient temperature adjustment.
– by connecting specified terminals of the multimeter with copper wires
on banana plugs as short as possible.
– by removing all test leads from the terminals of the multimeter.
After each adjustment, the display will show . If the calibration fails, the
multimeter will emit a beep, and an error number will be displayed. Calibration
error messages are described in “Calibration Error Codes” on page 54.
Never turn off the multimeter during an adjustment. This may delete the
calibration memory for the present function.
42 Keysight U1241C/U1242C Service Guide
Page 43
Rotary switch position for calibration
1
2
3
4
5
6
7
Figure 1-8 Rotary switch
Calibration Procedures 1
Turn the rotary switch to the positions as indicated above for the following
calibration functions:
Table 1-14 Rotary switch positions for calibration
Rotary switch position Calibration function
1AC V or Vsense
2DC V
3Resistance
4 Diode or capacitance
5DC/AC μ.mA
6DC/AC A
7 DC/AC mV or temperature
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1 Calibration Procedures
Valid adjustment input values
Adjustment can be accomplished using the following input values.
Table 1-15 Adjustment input values
Test function Step Reference value Valid reference input
1000.0 mV (55 Hz) 0.9 to 1.1 x Reference value
1000.0 mV (1 kHz) 0.9 to 1.1 x Reference value
AC V
Vsense
1000.0 mV
10.000 V
100.00 V
1000.0 V
[a]
Hi.10 V 10 V (55 Hz) High sense
Lo.30 V 30 V (55 Hz) Low sense
100.0 mV (55 Hz) 0.9 to 1.1 x Reference value
1000.0 mV (55 Hz) 0.9 to 1.1 x Reference value
1000.0 mV (10 kHz) 0.9 to 1.1 x Reference value
10.000 V (55 Hz) 0.9 to 1.1 x Reference value
10.000 V (1 kHz) 0.9 to 1.1 x Reference value
1.000 V (55 Hz) 0.9 to 1.1 x Reference value
10.000 V (55 Hz) 0.9 to 1.1 x Reference value
10.000 V (10 kHz) 0.9 to 1.1 x Reference value
10.00 V (55 Hz) 0.9 to 1.1 x Reference value
100.00 V (55 Hz) 0.9 to 1.1 x Reference value
100.00 V (1 kHz) 0.9 to 1.1 x Reference value
100.00 V (10 kHz) 0.9 to 1.1 x Reference value
100.0 V (55 Hz) 0.9 to 1.1 x Reference value
1000.0 V (55 Hz) 0.9 to 1.1 x Reference value
1000.0 V (1 kHz) 0.9 to 1.1 x Reference value
1000.0 V (10 kHz) 0.9 to 1.1 x Reference value
44 Keysight U1241C/U1242C Service Guide
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Calibration Procedures 1
Table 1-15 Adjustment input values (continued)
Test function Step Reference value Val id reference input
Short SHor Short V Ω / COM terminals
1000.0 mV 1000.0 mV 0.9 to 1.1 x Reference value
DC V
DC mV
AC mV
Temperature
Resistance
10.000 V 10.000 V 0.9 to 1.1 x Reference value
100.00 V 100.00 V 0.9 to 1.1 x Reference value
1000.0 V 1000.0 V 0.9 to 1.1 x Reference value
Short SHor Short V Ω / COM terminals
100.00 mV 100.00 mV 0.9 to 1.1 x Reference value
1000 mV
(600.0 mV)
100.00 mV
1000.0 mV
(600 mV)
[b]
Type-K 0000.0 ºC 0 ºC with ambient compensation
Short SHor Zero reference point
10.000 MΩ
1000.0 kΩ 1000.0 kΩ 0.9 to 1.1 x Reference value
100.00 kΩ 100.00 kΩ 0.9 to 1.1 x Reference value
10.000 kΩ 10.000 kΩ 0.9 to 1.1 x Reference value
300.0 mV 0.9 to 1.1 x Reference value
10.00 mV (55 Hz) 0.9 to 1.1 x Reference value
100.00 mV (55 Hz) 0.9 to 1.1 x Reference value
030.0 mV (55 Hz) 0.9 to 1.1 x Reference value
300.0 mV (55 Hz) 0.9 to 1.1 x Reference value
oPEn Open terminals
10.000 MΩ 0.9 to 1.1 x Reference value
1000.0 Ω 1000.0 Ω 0.9 to 1.1 x Reference value
Short SHor Short V Ω / COM terminals
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1 Calibration Procedures
Table 1-15 Adjustment input values (continued)
Test function Step Reference value Valid reference input
Open oPEn Open terminals
1000.0 nF
10.000 μF
100.0 nF 0.9 to 1.1 x Reference value
1000.0 nF 0.9 to 1.1 x Reference value
1.000 μF 0.9 to 1.1 x Reference value
10.000 μF 0.9 to 1.1 x Reference value
Capacitance
Diode
DC μ.mA
AC μ.mA
100.00 μF
10.00 μF 0.9 to 1.1 x Reference value
100.00 μF 0.9 to 1.1 x Reference value
100.0 μF 0.9 to 1.1 x Reference value
1000.0 μF
1000.0 μF 0.9 to 1.1 x Reference value
1.000 mF 0.9 to 1.1 x Reference value
10.000 mF
10.000 mF 0.9 to 1.1 x Reference value
Short SHor Short V Ω / COM terminals
2.100 V 1.000 V 0.9 to 1.1 x Reference value
Open oPEn Open terminals
1000.0 μA 1000.0 μA 0.9 to 1.1 x Reference value
10.000 mA 10.000 mA 0.9 to 1.1 x Reference value
100.00 mA 100.00 mA 0.9 to 1.1 x Reference value
1000.0 mA 300.00 mA 0.9 to 1.1 x Reference value
100.0 μA (55 Hz) 0.9 to 1.1 x Reference value
1000.0 μA
1000.0 μA (55 Hz) 0.9 to 1.1 x Reference value
1.000 mA (55 Hz) 0.9 to 1.1 x Reference value
10.000 mA
10.000 mA (55 Hz) 0.9 to 1.1 x Reference value
10.00 mA (55 Hz) 0.9 to 1.1 x Reference value
100.00 mA
100.00 mA (55 Hz) 0.9 to 1.1 x Reference value
030.0 mA (55 Hz) 0.7 to 1.3 x Reference value
1000.0 mA
300.0 mA (55 Hz) 0.9 to 1.1 x Reference value
46 Keysight U1241C/U1242C Service Guide
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Calibration Procedures 1
NOTE
V
Hold
Log
Table 1-15 Adjustment input values (continued)
Test function Step Reference value Val id reference input
DC A
Open oPEn Open terminals
10.000 A 10.000 A 0.7 to 1.3 x Reference value
AC A 10.000 A
[a] The sensor for the Vsense (non-contact voltage) calibration is located at the top center of the multimeter. Place the top area as close as
possible to the standard signal source without any loads.
[b] — Set the 5520A to internal reference.
— Prior to performing adjustment, connect one end of the K-type thermocouple (with miniature TC connector on both ends) to the 5520A TC
output, and the other end to a precision thermometer to verify that the source outputs the desired value. Adjust the source accordingly if
necessary.
— To perform the adjustment, connect one end of the K-type thermocouple (with miniature TC connector on both ends) to the 5520A TC
output, and the other end to the multimeter via a TC-to-banana adapter. Allow at least 1 hour for the multimeter to stabilize.
1.000 A (55 Hz) 0.7 to 1.3 x Reference value
10.000 A (55 Hz) 0.7 to 1.3 x Reference value
Vsense (non-contact voltage) calibration
– Keep the multimeter away from fluorescent lights, dimmable lights, motors,
and other electrical noise sources when running the tests. These electrical
noise sources can invalidate the calibration.
– It may be necessary in step 4 and step 8 below to slightly adjust the position
of the multimeter for maximum signal strength.
1 Turn the rotary switch to the position with shown on the display.
2 Connect a dual open type banana plug into the output voltage terminals of the
calibrator.
3 Ensure the “EARTH” button of the calibrator is turned ON.
4 Ensure the top of the multimeter is vertically and horizontally centered to
contact the banana plug's Hi terminal.
5 Set the source output to 10 V/55 Hz.
6 Press to start the calibration. If the calibration is successful,
will be displayed.
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1 Calibration Procedures
Hold
Log
7 Set the source output to 30 V/55 Hz.
8 Press to start the calibration.
9 When the calibration has completed, set the calibrator to the standby mode.
See Figure 1-9 for the multimeter’s display.
48 Keysight U1241C/U1242C Service Guide
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After appearing briefly
Pass
Fail
Press to start calibration.
Hold
Log
After appearing briefly
Calibration Procedures 1
Figure 1-9 Vsense (non-contact voltage) calibration
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1 Calibration Procedures
NOTE
Hold
Log
NOTE
Shift
Esc
View
Adjustment procedure
Review the “Test Considerations” on page 24 and “Adjustment considerations”
on page 42 before beginning the adjustment procedure.
1 Turn the rotary switch to the respective test function position as shown in
Table 1-15 detailing the adjustment input values.
2 Unsecure the multimeter to enter the adjustment mode. See “Unsecuring the
Multimeter for Calibration” on page 35.
3 Verify that the security code you entered is correct. If it is correct, the
multimeter will display the reference input value of the next calibration item.
and sequence of all the calibration items.
4 Enter the same value as a reference value on the primary display to the correct
terminals. Then press to start the calibration.
will appear briefly on the secondary display. See Ta ble 1-15 for the list
During calibration, the uncalibrated value is indicated on the primary display and
bar graph with indicated on the secondary display. The multimeter will
automatically check whether or not to save the calibration value. If the calibration
value passes the check, will appear briefly on the secondary display and
the value is saved before moving on to the next step. If the value is out of the
acceptable range, it will continue to display the current calibration value after an
error code is indicated briefly.
5 Check whether the right standard value has been applied or refer to
“Calibration Error Codes” on page 54.
6 Repeat step 4 and step 5 until calibration has completed for all calibration
values.
7 Press or turn the rotary switch to select other values to be calibrated.
Repeat step 6 and step 8.
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Calibration Procedures 1
Hold
Log
Shift
Esc
View
Hold
Log
Shift
Esc
View
8 When all calibrations have completed, press both
together for more than 1 second to exit the calibration mode. Alternatively,
you can also power off and on the multimeter again. The multimeter will return
to the normal measurement mode and is secured.
9 Verify the adjustments using the “Performance Verification Tests” on page 25.
Exiting the adjustment mode
1 Remove all the shorting plugs and connectors from the multimeter.
2 Record the new calibration count.
3 Press both
calibration mode.
4 Cycle the multimeter’s power. The multimeter will then be secured.
and together for more than 1 second to exit the
and
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1 Calibration Procedures
NOTE
Hz
MaxMinHzMaxMin
Calibration Count
You can query the multimeter to determine how many adjustments have been
performed.
The multimeter has been calibrated before it left the factory. You are
recommended to record the initial value of the calibration count once you
receive the multimeter.
The calibration count feature provides an independent “serialization” of your
calibrations. You can determine the number of times that your multimeter has
been calibrated. By monitoring the calibration count, you can determine if an
unauthorized calibration has been performed. The value is increased by one for
each calibration.
The calibration count is stored in nonvolatile memory and does not change with
power ON/OFF or after a remote interface reset. Your multimeter was calibrated
before it left the factory. When you receive your multimeter, take note of the
calibration counts as a record for maintenance.
The calibration count increases by one for each calibration point, from up
to the maximum . Once the maximum calibration count is reached, the
count will reset to . The calibration count can be read after the multimeter
has been unsecured. The calibration count cannot be programmed or reset. It is
an independent electronic calibration “serialization” value.
1 Press for more than 1 second in the adjustment mode to view the
calibration count.
2 Take note of the calibration count to keep track of the number of calibrations
that have been performed.
3 Press for more than 1 second to exit the calibration count mode.
52 Keysight U1241C/U1242C Service Guide
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Figure 1-10 Calibration count mode
Press
for >1 sec.
Hz
MaxMin
Calibration Procedures 1
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1 Calibration Procedures
Calibration Error Codes
The following errors indicate failures that may occur during a calibration.
Table 1-16 Calibration error codes
Error code Description (error message)
200/E200 Calibration error: calibration mode is secured
002/E002 Calibration error: secure code invalid
003/E003 Calibration error: serial number code invalid
004/E004 Calibration error: calibration aborted
005/E005 Calibration error: value out of range, or signal measurement out of range
006/E006 Calibration error: signal measurement out of range
007/E007 Calibration error: frequency out of range
008/E008 EEPROM write failure
54 Keysight U1241C/U1242C Service Guide
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Keysight U1241C/U1242C Handheld Digital Multimeter
Service Guide
2 Service and Maintenance
Troubleshooting 56
Fuse Replacement 57
Returning the Multimeter for Service 59
Replaceable Parts 60
Types of Service Available 61
Obtaining Repair Service (Worldwide) 62
This chapter will help you troubleshoot a failing multimeter. It also describes how
to obtain repair services and lists the replaceable assemblies.
55
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2 Service and Maintenance
WARNING
CAUTION
Troubleshooting
To avoid electrical shock, do not perform any servicing unless you are
qualified to do so.
Any repair or service which is not covered in this manual should only be
performed by qualified personnel.
If the multimeter fails to operate, check the batteries and the test leads. Replace
them if necessary. If the multimeter still does not function, check the operating
procedures in this manual. When servicing, use only the specified replacement
parts.
The following table will assist you in identifying some basic malfunctions.
Tab le 2-1 Operating checklist
Malfunction Identification
No display when powered ON using the rotary switch ✔ Verify the batteries health and replace batteries as necessary.
No beeper tone ✔ Verify that the beeper is enabled in the multimeter’s Setup mode.
Failed on current measurement ✔ Verify the fuses health and replace the fuses as necessary.
✔ Verify the optical side of the IR-USB cable connected to the
multimeter — the Keysight logo should be facing up.
Failed on remote control
56 Keysight U1241C/U1242C Service Guide
✔ Verify the baud rate, data bit, and parity settings in the multimeter’s
Setup mode. (Default values are 9600, 8, and none.)
✔ Verify that the driver for the IR-USB interface is installed.
Page 57
Fuse Replacement
NOTE
CAUTION
No recalibration is required after replacing the fuse.
The current input terminals of your multimeter are fuse-protected. The fuses are
located next to the battery compartment.
The terminal is protected by a 10 x 35 mm 440 mA/1000 V 30 kA
fast-acting fuse (Fuse 1).
The A terminal is protected by a 10 x 38 mm 11 A/1000 V 30 kA fast-acting fuse
(Fuse 2).
If you are certain that the fuse is faulty, replace it with one of the same size and
rating.
Before you proceed with the fuse replacement, remove all cable connections
to the terminals and ensure that the rotary switch is at the OFF position.
Service and Maintenance 2
1 Lift the tilt stand as shown on the right.
2 Loosen and remove the two screws with a
suitable Phillips screwdriver as shown on the
right.
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2 Service and Maintenance
Fuse 2 protecting
A terminal
Fuse 1 protecting
terminal
4 Lift the inner cover to access the fuse
compartment.
3 Lift and remove the fuse cover as shown on
the left.
5 Remove the defective fuse gently by prying
one end of the fuse with a flathead
screwdriver and removing it out of the fuse
bracket.
7 Ensure that the inner cover is positioned
properly.
8 Close the inner cover of the fuse
compartment.
9 Place the fuse cover back in its original
position and tighten the screws.
58 Keysight U1241C/U1242C Service Guide
6 Replace with a new fuse of the same size and
rating.
Page 59
Returning the Multimeter for Service
NOTE
Before shipping your multimeter for repair or replacement, Keysight recommends
that you acquire the shipping instructions from the Keysight Service Center. A
clear understanding of the shipping instructions is necessary to secure your
multimeter for shipment.
1 Attach a tag to the multimeter with the following information:
– Name and address of owner
– Multimeter’s model number
– Multimeter’s serial number
– Description of the service required or failure indications
2 Remove all accessories from the multimeter. Do not include accessories
unless they are associated with the failure symptoms.
3 Place the multimeter in its original container with appropriate packaging
material for shipping.
If the original shipping container is not available, place your multimeter in a
container which will ensure at least 4 inches of compressible packaging material
around all sides for the multimeter. Use static-free packaging materials to avoid
additional damage to your multimeter.
Service and Maintenance 2
Keysight suggests that you always insure your shipments.
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2 Service and Maintenance
Replaceable Parts
This section contains information for ordering replacement parts for your
multimeter. You can find the multimeter support parts list in the Keysight's Test &
Measurement Parts Catalog: http://www.keysight.com/find/parts
The parts list includes a brief description of each part with its corresponding
Keysight part number.
To order replaceable parts
You can order replaceable parts from Keysight using the Keysight part number.
Note that not all parts listed are available as field-replaceable parts.
To order replaceable parts from Keysight, do the following:
1 Contact your nearest Keysight Sales Office or Service Center.
2 Identify the parts by the Keysight part number shown in the support parts list.
3 Provide the multimeter’s model number and serial number.
60 Keysight U1241C/U1242C Service Guide
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Types of Service Available
If your multimeter fails during the warranty period, Keysight will repair or replace
it under the terms of your warranty. After your warranty expires, Keysight offers
repair services at competitive prices.
Extended service contracts
Many Keysight products are available with optional service contracts that extend
the covered period after the standard warranty expires. If you have such a service
contract and your multimeter fails during the covered period, Keysight will repair
or replace it in accordance with the contract.
Service and Maintenance 2
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2 Service and Maintenance
Obtaining Repair Service (Worldwide)
To obtain service for your multimeter (in-warranty, under service contract, or
post-warranty), contact your nearest Keysight Service Center. They will arrange to
have your unit repaired or replaced, and can provide warranty or repair-cost
information where applicable.
To obtain warranty, service, or technical support information, you can contact
Keysight worldwide via our Web link: www.keysight.com/find/assist,
or contact your Keysight representative.
Before shipping your multimeter, request the Keysight Service Center to provide
shipping instructions, including what components to ship. Keysight recommends
that you retain the original shipping carton for use in such shipments.
62 Keysight U1241C/U1242C Service Guide
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This information is subject to change
without notice. Always refer to the
Keysight website for the latest
revision.
© Keysight Technologies 2016-2017
Edition 5, April 21, 2017
Printed in Malaysia
*U1241-90104*
U1241-90104
www.keysight.com
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