Acer 5740 turn on then turns off

Discussion in 'Computer Repair' started by Anand salunke, Aug 16, 2016.

Acer 5740 turn on then turns off 5 5 1votes
5/5, 1 vote

  1. Anand salunke

    Anand salunke VIP MENBER

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    Hey guys,

    ACER 5740 (motherboard JV50-CP MB 09285-1M) does not turn on and no display.

    When power button is pressed, power leds turn on, exactly after 1 second, they turn off.

    I checked all voltages and they seem fine, when power button is pressed. PLTRST is also fine.

    Exactly after one second from turn on, it looks that SLP_S3# and SLP_S4# are turned off by PCH causing system off. All powergood signal is OK.

    I have downloaded BIOS from ACER website and flashed, but the set still does not turn on. I have also reflowed the PCH HM55, but no luck.

    I also tried HM55 replacement, but symptoms are still the same.

    Another interesting observation is that the SIO/KBC does not pull up RSMRST to PCH upon power button press, is this normal on this board?
     
  2. ThienBui

    ThienBui There's always more to learn.
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    You have test BIOS Clear me ?
     
  3. Anand salunke

    Anand salunke VIP MENBER

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    Hi,
    Thanks for reply, I tried, but no luck. Can you post clear me for this board or give me directions how to produce clear ME?

    Can such issues occur because of ME?
     
  4. Anand salunke

    Anand salunke VIP MENBER

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    Thanks. I will try this file.
    Can you confirm the RSMRST behaviour on this board is normal? I mean KBC pull up PCH_RSMRST on power button press or not?
     
  5. ThienBui

    ThienBui There's always more to learn.
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    May be higher or lower, It depends on the board.
    :D
     
  6. Anand salunke

    Anand salunke VIP MENBER

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    Right. Depends on the board. For HM55, PCH_RSMRST is pulled high upon power button press and shall remain high until system is shut down. On my board, this transition is absent. Is it possible that the KBC is bad, because it is responsible for generating PCH_RSMRST.

    Dont get angry, I am desperately looking for solution. Would be helpful, if somebody can send power sequence diagram for this motherboard.
     
  7. ThienBui

    ThienBui There's always more to learn.
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    Have Schematics :D
    https://vinafix.vn/threads/acer-aspire-5340-5740-5740g-wistron-jv50-cp-09285.12539/

    Acer-Gateway - Acer Aspire 5340 5740 5740G (Wistron JV50-CP 09285)

    Vinafix.vn
    vinafix.vn



    Or Changes KBC if necessary.
     
  8. Anand salunke

    Anand salunke VIP MENBER

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    KBC changed, but still no improvement. Tried clear me also, but no luck.
     
  9. fred69

    fred69 VIP PRO

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    verify if you have a circuit that have more current consumption.
    Remove CPU and verify if shutdown issue is still present
    First verify if you have CPU_RST# high
    if it's right, verify if it execute first instructions, place scope probe trigger on spi flash CS# fall edge, if ok cpu start run Bios instruction
    Verify if calibration memory SPD run ok => scope probe on data and CLK smbus memory.
     
  10. Anand salunke

    Anand salunke VIP MENBER

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    Thanks Fred. I will definitely try this
     

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