Intel D865PERL - no Vcore after replacing MOSFETs and MOSFET drivers

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  • kotel studios
    Senior Member
    • Dec 2024
    • 153
    • Poland
    #1

    Intel D865PERL - no Vcore after replacing MOSFETs and MOSFET drivers

    Hi,

    Finally got time to fix this board up.
    At first it didn't give any POST codes. Turns out it was an unsupported Celeron D cpu. After dropping in an Celery 2.6gHz the CPU came out of reset with clock signal, but still no post codes. For a while it did work when I applied pressure to the ADP3168 chip, but on next reboot the MOSFETs started to burn. Then I left it as is for months.

    Now I came back prepared. Replaced the bad MOSFETs and the ADPxx18k drivers. Now I don't get any MOSFETs blowing up issues anymore. But sadly, the Vcore is missing. The whole VRM isn't switching. CPU is stone cold (tested in another machine, works) and stuck in reset... I do have an ADP3166 to replace the ADP3168, but pin 6 on both are different. On 3166 it's CROWBAR which can short 12v to GND on demand, while on 3168 it is VID5. Not sure if I can use the 3166 here....

    Drivers get their 2.8v on pin 3, original ADP3168 also has 1.2v on pin 11, so there shouldn't be any problems here. I see the high side MOSFETs getting 12v on their gates, but nothing on the outputs, low side get their 12v on source, but nothing on drain.....

    Any ideas?
    Last edited by kotel studios; 04-22-2025, 06:16 AM.
    Tags: None
    • kotel studios
      Senior Member
      • Dec 2024
      • 153
      • Poland
      #2
      After some troubleshooting I found the culprits, missing FB, FBRTN, PWRGD which makes the VRM not switch (no PWD 1-4 voltage). FB and FBRTN are all connected to their respective rails. Injecting FB makes PWRGD still stay low....
      Injecting Vcore directly onto the coils makes the CPU get out of reset, but it's still not posting...
      All I know is that the ADP3168 sees some unknown fault and halts the switching of the VRM and that's it.
      Any ideas?

      ​

        Comment

        • ribcage
          Member
          • Sep 2020
          • 45
          • Earth
          #3
          It's very common for one capacitor to fail on this board. Often it's nichicon HM(M) 2200µF 10V, between RAM and SATA ports. It causes intermittent POST.

            Comment

            • kotel studios
              Senior Member
              • Dec 2024
              • 153
              • Poland
              #4
              Originally posted by ribcage
              It's very common for one capacitor to fail on this board. Often it's nichicon HM(M) 2200µF 10V, between RAM and SATA ports. It causes intermittent POST.
              Well, it might've been the case earlier on, now this board is total e-waste....
              Not only did I order the wrong chip (ADP3166), I also destroyed pin 11 (EN) on the original chip and the pads bellow them onboard......
              Sure, trace repair is possible, but is it really worth putting in another 50zł just to not have a guarantee if it's not gonna work?

                Comment

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