Wake up from sleep problem

Discussion in 'Mac Pro' started by hlyi, Apr 21, 2019.

  1. hlyi macrumors newbie

    Joined:
    Apr 21, 2019
    #1
    I acquired a cMP5,1 recently. Everything seems to work okay except there is a problem wake up from sleep: the power LED lights up, other than that nothing seems to work, no display, didn't response to "ping" from other computer. tried resetting NVRAM/SMC, it didn't help. Is this logic board problem or power supply problem? Thanks!
     
  2. tsialex macrumors 601

    tsialex

    Joined:
    Jun 13, 2016
    Location:
    Brazil
    #2
    Waking from sleep is a common symptom of PSU problems, but can be caused by the backplane (correct name of MP5,1 logic board) too. First step is to test a known working PSU.
     
  3. hlyi thread starter macrumors newbie

    Joined:
    Apr 21, 2019
    #3
    @tsialex Thanks a lot for the feedback! Unfortunately, I couldn't locate anther cMP to swap PSU. Any other way or test could be done to determinate the PSU problem vs logic board problem?
     
  4. tsialex macrumors 601

    tsialex

    Joined:
    Jun 13, 2016
    Location:
    Brazil
    #4
    If you have a logging multimeter/scope with memory, you can detected when the PSU fails to send power and mess with sleep, but it's a very time consuming job doing this way.

    Diag lights on the backplane are not made for diagnosing a failing PSU, so it's useless for this problem. If you don't have the necessary equipment, I don't know of any definitive tests without exchanging parts with a working Mac Pro.
     
  5. hlyi thread starter macrumors newbie

    Joined:
    Apr 21, 2019
    #5
    Thanks for the tips @tsialex!. Guess I need pull PSU out and look for bad cap then...
     

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4 April 21, 2019