Keysight U1281A Service Manual
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Keysight U1281A Service Manual

Handheld digital multimeter
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Keysight U1281A/U1282A
Handheld Digital Multimeter
Service Guide

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Summary of Contents for Keysight U1281A

  • Page 1 Keysight U1281A/U1282A Handheld Digital Multimeter Service Guide...

  • Page 2: Safety Information

    Conformity. understood and met. where in the EULA. Keysight shall be under no obligation to update, revise or otherwise modify the Software. With WARNING respect to any technical data as defined by FAR 2.101, pursuant to FAR...

  • Page 3: Safety Symbols

    Warning or Caution information) Equipment protected throughout by Earth (ground) terminal double insulation or reinforced insulation CAT III CAT IV Category III 1000 V overvoltage Category IV 600 V overvoltage protection protection 1000 V 600 V Keysight U1281A/U1282A Service Guide...

  • Page 4: Safety Considerations

    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.
  • Page 5 – Always use the specified battery type. The power for the multimeter is supplied with four standard 1.5 V AA batteries. Observe the correct polarity markings before you insert the batteries to ensure proper insertion of the batteries in the multimeter. Keysight U1281A/U1282A Service Guide...

  • Page 6: Measurement Category

    Measurement Category The U1281A/U1282A has a safety rating 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.

  • Page 7: Environmental Conditions

    Environmental Conditions The U1281A/U1282A is designed for indoor use and in an area with low condensation. The table below shows the general environmental requirements for this instrument. Environmental cond ition Requirement Operating condition – –20 °C to 55 °C, 0% to 80% RH (non-condensing)

  • Page 8: Regulatory Information

    Regulatory Information The U1281A/U1282A complies with the following safety and Electromagnetic Compatibility (EMC) compliances: Safety compliance – IEC/EN 61010-1:2010 (3rd Edition) – IEC/EN 61010-2-033:2012 (First Edition) – CAN/CSA-C22.2 No. 61010-1-12 – CAN/CSA-C22.2 No. 61010-033-12 – ANSI/UL Std. No. 61010-1-12 – ANSI/UL Std. No. 61010-033-12 EMC compliance –...

  • Page 9: Regulatory Markings

    EMC Declaration. This is a Class A substance elements are expected to instrument suitable for professional leak or deteriorate during normal use. use and in electromagnetic Forty years is the expected useful life environment outside of the home. of the product. Keysight U1281A/U1282A Service Guide...

  • Page 10: Waste Electrical And Electronic Equipment (Weee) Directive 2002/96/Ec

    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/U1281A www.keysight.com/find/U1282A...

  • Page 11: Table Of Contents

    ........37 Unsecuring the Multimeter for Calibration ..... .38 Keysight U1281A/U1282A Service Guide...
  • Page 12 ....... . 66 Obtaining Repair Service (Worldwide) ......67 Keysight U1281A/U1282A Service Guide...

  • Page 13: Keysight U1281A/U1282A Service Guide

    ....... .52 Figure 1-9 Multimeter display for calibration count ...56 Keysight U1281A/U1282A Service Guide...
  • Page 14 THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight U1281A/U1282A Service Guide...

  • Page 15: List Of Tables

    ......57 Table 2-1 Operating checklist ......60 Keysight U1281A/U1282A Service Guide...
  • Page 16 THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight U1281A/U1282A Service Guide...
  • Page 17 Keysight U1281A/U1282A Handheld Digital Multimeter Service Guide Calibration Procedures Calibration Overview Recommended Test Equipment Basic Operating Tests Calibration Process Test Considerations Performance Verification Tests Calibration Security Unsecuring the Multimeter for Calibration Using the Front Panel for Adjustments Calibration Count Calibration Error Codes This chapter helps you to verify the multimeter performance and to make adjustments where necessary.

  • Page 18: Calibration Procedures

    The nonvolatile EEPROM calibration memory is retained even when the 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.

  • Page 19: Recommended Adjustment

    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.

  • Page 20: Recommended Test Equipment

    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 multimeter as the target calibration value.

  • Page 21: Basic Operating Tests

    Press and turn on the multimeter by turning the rotary switch from to any other position to view all annunciators of the display. Compare the display with the example in Figure 1-1. Figure 1-1 Display screen Keysight U1281A/U1282A Service Guide...

  • Page 22: Input Warning Test (A Terminal)

    Perform the following steps to replicate the input terminal warning test: 1 Turn the rotary switch to the position. 2 Insert the red test lead to the input terminal. 3 Insert the black test lead to the input terminal. Keysight U1281A/U1282A Service Guide...
  • Page 23 Calibration Procedures Vsense U1282A True RMS Multimeter Vsense Peak Auto Dual 10A MAX CAT IV 600V FUSED CAT III 1000V 440mA FUSED Figure 1-2 Example of A-Err for wrong terminal input Keysight U1281A/U1282A Service Guide...

  • Page 24: Input Warning Test (Μ.ma Terminal)

    Perform the following steps to replicate the terminal input warning test: 1 Turn the rotary switch to the position. 2 Insert the red test lead to the input terminal. 3 Insert the black test lead to the input terminal. Keysight U1281A/U1282A Service Guide...
  • Page 25 Calibration Procedures Vsense U1282A True RMS Multimeter Vsense Peak Auto Dual 10A MAX CAT IV 600V FUSED CAT III 1000V 440mA FUSED Figure 1-3 Example of μAErr for wrong terminal input Keysight U1281A/U1282A Service Guide...

  • Page 26: Calibration Process

    – 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. Keysight U1281A/U1282A Service Guide...

  • Page 27: Performance Verification Tests

    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 U1281A/U1282A Data Sheet (available for download at http://literature.cdn.keysight.com/litweb/pdf/5992-0847EN.pdf). The performance verification tests are recommended as acceptance tests when you first receive the multimeter.

  • Page 28: Table 1-3 Dc Mv (Mv) Performance Verification Tests

    Turn the rotary switch to the position. 600 mV ±0.20 mV ±0.20 mV 600 mV [a] The accuracy is specified after the Null function is used to subtract the thermal effect (by shorting the test leads) before measuring the signal. Keysight U1281A/U1282A Service Guide...

  • Page 29: Table 1-4 Ac V (V) Performance Verification Tests

    ±12.70 V 1000 V, 45 Hz ±5.5 V ±5.5 V 1000 V, 1 kHz ±5.5 V ±5.5 V 1000 V 1000 V, 10 kHz ±9.5 V ±9.5 V 300 V, 20 kHz ±10.5 V ±10.5 V Keysight U1281A/U1282A Service Guide...

  • Page 30: Table 1-5 Ac Mv (Mv) Performance Verification Tests

    ±31.60 mV Table 1-6 LPF performance verification test Error from nominal 1 year 5520A/5522A Test function Range output U1281A U1282A 3 V, 20 Hz ±0.0660 V While the rotary switch is in the position, press Shift Keysight U1281A/U1282A Service Guide...

  • Page 31: Table 1-8 Dc Current (A) Performance Verification Tests

    10 A to 20 A, current can be measured for 30 seconds maximum. After measuring > 10 A current, cool down the multimeter for twice the measuring time taken and use the Null ( ) function to zero the thermal effect before proceeding for low current measurement. Keysight U1281A/U1282A Service Guide...

  • Page 32: Table 1-9 Ac Current (A) Performance Verification Tests

    10 A to 20 A, current can be measured for 30 seconds maximum. After measuring > 10 A current, cool down the multimeter for twice the measuring time taken and use the Null ( ) function to zero the thermal effect before proceeding for low current measurement. Keysight U1281A/U1282A Service Guide...

  • Page 33: Table 1-10 Ac Current (Μa.ma) Performance Verification Tests

    ) function to zero the thermal effect before proceeding with a low current measurement or checking the current offset. Table 1-11 Diode performance verification test Error from nominal 1 year 5520A/5522A Test function Range output U1281A U1282A Diode ±0.006 V ±0.006 V Turn the rotary switch to the position. Keysight U1281A/U1282A Service Guide...

  • Page 34: Table 1-12 Capacitance Performance Verification Tests

    ±0.903 MΩ ±0.903 MΩ [a] The accuracy is specified after the Null function is used to subtract the test lead resistance and thermal effect. Keep the multimeter away from heat and ensure it is well ventilated. Keysight U1281A/U1282A Service Guide...

  • Page 35: Table 1-14 Conductance Performance Verification Test

    Range output U1281A U1282A Duty cycle 1 to 99 % 50 Hz at 50%, 6 Vpp ±0.315% ±0.315% While the rotary switch is in the , press Save until the measurements are displayed as percentages (%). Keysight U1281A/U1282A Service Guide...

  • Page 36: Table 1-17 Temperature Performance Verification Test

    Error from nominal 1 year Test function Range 33522B output U1281A U1282A Frequency counter 9.9999 MHz 1 MHz, 200 mV ±0.0005 MHz While the rotary switch is in the position, press 99.999 MHz 20 MHz, 330 mV ±0.0054 MHz Shift Keysight U1281A/U1282A Service Guide...

  • Page 37: Calibration Security

    The security code is stored in nonvolatile memory, and does not change when power has been turned off. The security code may contain up to four numeric characters. Keysight U1281A/U1282A Service Guide...

  • Page 38: Unsecuring The Multimeter For Calibration

    Figure 1-4 Calibration security code entry display 2 Key in your security code. Hold – Press to move the cursor to the left or to the right. Vsense – Press to increment or decrement the digit. Keysight U1281A/U1282A Service Guide...
  • Page 39 Shift 4 Exit the unsecured mode by pressing together to secure the Save multimeter again. Figure 1-5 for the multimeter display. Keysight U1281A/U1282A Service Guide...
  • Page 40 1 second. Press Hold for left or Fail right. Vsense Press After appearing briefly increment or decrement the digit. Pass Press Save save your input After appearing briefly Figure 1-5 Multimeter display when unsecuring the multimeter Keysight U1281A/U1282A Service Guide...

  • Page 41: To Change The Calibration Security Code

    Save If the new calibration security code has been successfully stored, the display will show 4 Record down your new calibration security code, and store it in a safe location. Figure 1-6 for the multimeter display. Keysight U1281A/U1282A Service Guide...
  • Page 42 1 second. Pass Hold Press for left Press Save or right. save your input Vsense Press to increment or decrement the digit. After appearing briefly Figure 1-6 Multimeter display when changing the calibration security code Keysight U1281A/U1282A Service Guide...

  • Page 43: To Reset The Calibration Security Code To Its Factory Default

    – To enter a new security code, see “To change the calibration security code” on page 41. Ensure that you record down the new security code. Keysight U1281A/U1282A Service Guide...
  • Page 44 Vsense Press After appearing briefly increment or decrement the digit. Pass Press Save After appearing briefly save your input Figure 1-7 Multimeter display when resetting the calibration security code to its factory default Keysight U1281A/U1282A Service Guide...

  • Page 45: Using The Front Panel For Adjustments

    Calibration error messages are described in “Calibration Error Codes” on page 57. Never turn off the multimeter during an adjustment. This may delete the CAUTION calibration memory for the present function. Keysight U1281A/U1282A Service Guide...

  • Page 46: Valid Adjustment Input Values

    300.00 V (1 kHz) 0.9 to 1.1 x Reference value 300.00 V (10 kHz) 0.9 to 1.1 x Reference value Hi.10 V 10.00 V (55 Hz) High Sense Vsense Lo.30 V 30.00 V (55 Hz) Low Sense Keysight U1281A/U1282A Service Guide...
  • Page 47 600.00 mV (55 Hz) 0.9 to 1.1 x Reference value 300.00 mV (1 kHz) 0.9 to 1.1 x Reference value 300.00 mV (10 kHz) 0.9 to 1.1 x Reference value Type-K 0.0 ºC 0.0 ºC with ambient compensation Temperature Keysight U1281A/U1282A Service Guide...
  • Page 48 3.00 kΩ 0.9 to 1.1 x Reference value 600.00 Ω 300.00 Ω 0.9 to 1.1 x Reference value 60.00 Ω 30.00 Ω 0.9 to 1.1 x Reference value Short SHort Short V Ω / COM terminals Keysight U1281A/U1282A Service Guide...
  • Page 49 0.9 to 1.1 x Reference value DC μA/mA 6.00 mA 3.00 mA 0.9 to 1.1 x Reference value 60.00 mA 30.00 mA 0.9 to 1.1 x Reference value 600.00 mA 300.00 mA 0.9 to 1.1 x Reference value Keysight U1281A/U1282A Service Guide...
  • Page 50 — 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. Keysight U1281A/U1282A Service Guide...

  • Page 51: Vsense (Non-Contact Voltage) Calibration

    7 Set the source output to 30 V/55 Hz. 8 Press to start the calibration process. Save 9 Set the calibrator to standby mode when the calibration is done. Figure 1-8 for the multimeter display. Keysight U1281A/U1282A Service Guide...
  • Page 52 Calibration Procedures Press to start Save calibration. Fail Pass After appearing briefly After appearing briefly Figure 1-8 Multimeter display for Vsense (non-contact voltage) calibration Keysight U1281A/U1282A Service Guide...

  • Page 53: Adjustment Procedure

    57. 6 Repeat step 4 step 5 until calibration is complete for all calibration values. Shift 7 Press or rotate the rotary switch to select other values to be calibrated. Repeat step 6 step Keysight U1281A/U1282A Service Guide...

  • Page 54: Exiting The Adjustment Mode

    1 Remove all the shorting plugs and connectors from the multimeter. 2 Record the new calibration count. Shift 3 Press together to exit calibration mode. Save 4 Cycle the multimeter's power. The multimeter will then be secured. Keysight U1281A/U1282A Service Guide...

  • Page 55: Calibration Count

    1 second in 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. Hold 3 Press for more than 1 second to exit the calibration count mode. Keysight U1281A/U1282A Service Guide...
  • Page 56 Calibration Procedures Hold Press more than 1 second Figure 1-9 Multimeter display for calibration count Keysight U1281A/U1282A Service Guide...

  • Page 57: Calibration Error Codes

    Calibration error: serial number code invalid 004/E004 Calibration error: calibration aborted 005/E005 Calibration error: value 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 Keysight U1281A/U1282A Service Guide...
  • Page 58 Calibration Procedures THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight U1281A/U1282A Service Guide...
  • Page 59 Keysight U1281A/U1282A Handheld Digital Multimeter Service Guide Service and Maintenance Troubleshooting Fuse Replacement Returning the Multimeter for Service Replaceable Parts Types of Service Available Obtaining Repair Service (Worldwide) This chapter will help you troubleshoot a failing multimeter. It also describes how...

  • Page 60: Service And Maintenance

    – Verify the condition of the fuses 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 – Verify the baud rate, data bit, and parity settings in the multimeter’s setup mode.

  • Page 61: Fuse Replacement

    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 CAUTION to the terminals and ensure that the rotary switch is at the OFF position. Keysight U1281A/U1282A Service Guide...
  • Page 62 2 Loosen and remove the two screws with a suitable Phillips screwdriver as shown on the right. 3 Lift and remove the fuse cover as shown on the left. Keysight U1281A/U1282A Service Guide...
  • Page 63 8 Close the inner rubber cover of the fuse compartment. 9 Place the fuse cover back in its original position and tighten the screws. 10 Finally fit the orange rubber holster back on the multimeter. Keysight U1281A/U1282A Service Guide...

  • Page 64: Returning The Multimeter For Service

    Returning the Multimeter for Service 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 product for shipment.

  • Page 65: 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 model number and serial number.

  • Page 66: Types Of Service Available

    Service and Maintenance 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.

  • Page 67: Obtaining Repair Service (Worldwide)

    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.
  • Page 68 Service and Maintenance THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight U1281A/U1282A Service Guide...
  • Page 69 This information is subject to change without notice. Always refer to the English version at the Keysight website for the latest revision. © Keysight Technologies 2016-2017 Edition 4, June 30, 2017 Printed in Malaysia *U1281-90002* U1281-90002 www.keysight.com...

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U1282a

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