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Fluke 289 multimeter not working

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    #21
    Re: Fluke 289 multimeter not working

    Thanks,
    I will check Q22 and power supply voltages.
    And I will try to access debug console
    with ExtraPuTTY (if MCU is working).
    Last edited by Pauldg1; 04-09-2021, 01:09 PM.

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      #22
      Re: Fluke 289 multimeter not working

      I have checked some voltages on the board.
      I noticed that the 5V after U17 (5V LDO) is present only for 18,6msec after startup.
      See attachement with plot of output U17 after turning on multimeter.
      After startup the enable pin of U17 is made low for only 18,6msec by the MCU M340F. So most of the time the 5V is 0,7V instead of 5V (TP3).
      The 32kHz is present on xtal near M430F. Another board voltage is 3,046V, for example on C42.

      I don't see debug information on TX of J5. Should it present when turning on multimeter?

      Hope this info help to explain why 5V enable pin is turned off by M340F.
      Attached Files
      Last edited by Pauldg1; 04-11-2021, 09:47 AM.

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