MSI 785GM-E51 Mother board issue: CPU Phase Power leds on for 4 phases

Discussion in 'Technical Repair' started by rxyzm, Aug 20, 2016.

  1. rxyzm

    Thread Starter New Member

    Apr 7, 2013
    11
    0
    Hello,

    My desktop motherboard (MSI 785GM-E51, AMD Phenom II Processor) has failed.

    FYI - MSI states in their user manual for the motherboard that it is designed for providing power to CPU by phases. As I understand it, as the CPU requires more power, additional phases are switched on/off depending on the load.

    Well, this time, when the machine boot started, the power indicators flashed in usual pattern, and then suddenly all 4 leds lit up and stayed on.

    The Power supply switches on if I try to start the machine; also, the ventilation fans start and stay on. So it indicates basic circuitry required to switch on power supply is working fine. After this, the machine does not boot up, no beeps, no video signal - nothing. The 4 leds stay lit.

    My options now are to look for are any blown micro-fuses (board mount), power monitor chip etc. When I checked board visually and touched parts in the power section of the MOBO, nothing seemed to be out of place (burnt, hot parts). But, I do not have the service manual an/or board component layout diagram to get in to it. Tracing power connections in a multi-layer board is a pain because of distributed power planes.

    Trying to find the information on motherboard fault finding guidelines and also service manual for the board. Will appreciate any help in fixing this issue.

    With Warm Regards,

    Ravi
     
  2. paulktreg

    Distinguished Member

    Jun 2, 2008
    611
    120
    I doubt very much a service manual was ever even written.

    I appreciate you want to fix it yourself but you could probably pick up a cheap alternative motherboard on ebay for very little money.
     
  3. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,386
    496
    My money are on busted capacitors. There is website called: badcaps.com or some such. You might want to take a stroll down there.
     
  4. rxyzm

    Thread Starter New Member

    Apr 7, 2013
    11
    0
    Thank you Paul.

    BTW - there is a website eserviceinfo.com. This site seems to have very many service manuals available freely. I did find some MSI motherboard circuits books. Now need to explore them in detail.

    With Warm Regards,

    Ravi
     
  5. rxyzm

    Thread Starter New Member

    Apr 7, 2013
    11
    0
    Thank you Shteii01. Appreciate your help.

    I will find out about madcaps site and visit the same.

    With Warm Regards,

    Ravi
     
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