Megger pat 4 dv/3 timing issue

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  • llonen
    Badcaps Veteran
    • Sep 2014
    • 495
    • hampshire

    #1

    Megger pat 4 dv/3 timing issue

    So I have one of these in the workshop which I have been using for some years to test equipment under repair before returning to clients, the machine has been regularly calibrated without issue.

    Just recently though I have found there is a timing issue with each test for instance test for electrical resistance (set to 5 seconds) is taking less than 2 seconds, an earth bond test (set for 5 seconds) again takes less than 2 seconds. The problem seems to vary and affects all of the instrument tests.

    I have carried out a factory default settings reset and it has made no difference, I have yet to disassemble the machine so include a picture of the unit for reference, I have the full service manuals.

    thanking anyone who may be able to offer advice in advance
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  • stj
    Great Sage 齊天大聖
    • Dec 2009
    • 30985
    • Albion

    #2
    Re: Megger pat 4 dv/3 timing issue

    probably using a capacitor for a timing circuit.

    Comment

    • llonen
      Badcaps Veteran
      • Sep 2014
      • 495
      • hampshire

      #3
      Re: Megger pat 4 dv/3 timing issue

      There is a real time clock module (BQ4847YMT) which contains a Lithium Battery power source, a crystal controlled Clock / calendar module. This clock integrates, a time of day, 100 year calendar, CPU supervisor watchdog, a battery and timing crystal, the chip is socketed.

      looks to be the likely culprit
      Last edited by llonen; 09-17-2016, 05:06 PM.

      Comment

      • stj
        Great Sage 齊天大聖
        • Dec 2009
        • 30985
        • Albion

        #4
        Re: Megger pat 4 dv/3 timing issue

        pictures would help

        Comment

        • llonen
          Badcaps Veteran
          • Sep 2014
          • 495
          • hampshire

          #5
          Re: Megger pat 4 dv/3 timing issue

          Replaced BQ4847YMT real time clock module appears to have solved the problem

          Comment

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