Announcement

Collapse
No announcement yet.

Acer Nitro 5 model N20C2 board LA-K862P black screen

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
    #1

    Acer Nitro 5 model N20C2 board LA-K862P black screen

    I have this laptop: charging light is on when connected to the charger, when I push the power button you can hear the fans spinning for a three seconds, the keyboard backlight it turning on, the caps lock key is unresponsive, no image on screen. Only a couple of times it booted with image for a few seconds and then reboots to black screen. When it is frozen with black screen and lit keyboard, I can keep pressed the power button to shut it completely.
    I downloaded schematics in this forum ( https://www.badcaps.net/forum/troubl...862p-schematic ) and started checking.
    19 volts dcin is present after the first two mosfets and on thr PRB46. PQM2 looks shorted? (6 ohm from pin 1 to pin 5 )
    Any suggestion?
    Tags: None
    #2
    So that is 1.2v power supply according to the schematic. Un-solder jumper PJM2 and then see which side of that jumper the short is on. It feeds the Ram and CPU. Remove the ram if not removed to see if that makes a difference. Otherwise if it is on CPU side and not the ram then could be dead CPU.

    But I am not sure what resistance that cpu should be, Can be pretty low.

    EDIT - I just checked an Acer Predator 300 Helios ( LA-J891P) that I am working on that still boots but with secondary GPU issue and the CPU measures 6 ohms on one coil and 3 ohms on the others.

    It runs fine in windows so I don't think you have a problem there! Also you said it boots sometimes.. It wouldn't do this if shorted cpu.

    Intermittent booting, can be faulty ram or ram slot, failing GPU, dry solder joints on any of the big BGA's. Intermittent faults are a nightmare..

    Did you try a known working stick of ram and in each slot?

    I'm not sure if a corrupt bios could cause this, maybe try programming the bios again if you have a programmer.

    Hopefully someone with more knowledge will respond..

    Comment

      #3
      I've just tested with different ram sticks .. it booted correctly to windows login, than black screen again. And now still same problem.. fans spinning for three seconds, keyboard lit and nothing else. I think that maybe bios programming would not be useful with intermittent boots..but I could try.

      Comment

        #4
        If it is getting as far as windows then yeah I don't think it is the bios. You could try disabling the secondary graphics chip and see if it it runs ok on the integrated. You would have to disable power to the video ram and the gpu. Do you have the necessary equipment / knowledge to do this? I don't have any other ideas after that..

        When the screen goes black at windows logon does anything display on the external monitor?

        When it doesn't boot are all the power rails at the correct voltage? You can see them all on page 4 of the schematic.

        Actually since there are a lot of jumpers on this board for the power supplies it should easy enough to disable the discrete gpu without removing components, just remove the solder from the jumpers. If your not sure on the schematic which ones I can have a look.
        Last edited by reessi; 11-24-2024, 08:09 AM.

        Comment

          #5
          I'll inspect the motherboard under microscope for liquid spill/corrosion etc.

          Comment

            #6
            Originally posted by mcplslg123 View Post
            I'll inspect the motherboard under microscope for liquid spill/corrosion etc.
            done already, no corrosion found but I'll check again

            Comment

              #7
              Originally posted by reessi View Post
              If it is getting as far as windows then yeah I don't think it is the bios. You could try disabling the secondary graphics chip and see if it it runs ok on the integrated. You would have to disable power to the video ram and the gpu. Do you have the necessary equipment / knowledge to do this? I don't have any other ideas after that..

              When the screen goes black at windows logon does anything display on the external monitor?

              When it doesn't boot are all the power rails at the correct voltage? You can see them all on page 4 of the schematic.

              Actually since there are a lot of jumpers on this board for the power supplies it should easy enough to disable the discrete gpu without removing components, just remove the solder from the jumpers. If your not sure on the schematic which ones I can have a look.
              is there a jumper I can use to disable the discrete GPU? please explain... thanks in advance

              Comment

                #8
                No jumper specifically, I mean the jumpers that separate the output of the power supply's to the circuits they feed.

                You need to remove the jumpers from the outputs of the power supply's that feed the Video Ram and the GPU.

                I will try to look later or tomorrow on the Schematics.

                Comment

                Previous template Next
                Working...
                X