820-3662-a backlight but probably no picture (?)

Hi

I have a macbook that will always chime and very rarely show questionmark folder icon but mostly just black screen with backlight
I have tried the disk in another unit and it is healthy and boots with no issues
According to the client there was no physical nor liquid damage and looking at the board it does look like new
This unit wont progress beyond black screen with usb disk after standart resets

Just looking for a direction here

Kind regards
 
unfortunatelly not. I thought it was the display but now I get consistent Questionmark Folder
Also it doesnt seem to react to any pram or smc reset. Just stays as it is - black screen for about 5 min and then flashing folder
 
at least the power button works on the keyboard. Behaves the same with an external keyboard, although it doesnt seem to be detecting it as the capslock lights and num lock do not light up, also tried disconnecting the normal keyboard and only external but no difference
 

jgraffis

New member
have you tried on external (without screen plugged in) ?. i have 3-4 of this same model that no one can seem to get posting video to the internal display. still working on finding a solution to this common issue with these.
 
not consistent i'm afraid. the questionmark folder takes forever to appear (5min +) it is heating up - the unit. Put new thermarpaste but still, very hot within 3 minutes
 
Hi dukefawks, I was unable to do pram reset with external either.I am not convinced that it even detects the keyboard as no lights are present on the external keyboard
 

dukefawks

Administrator
This one is going to suck. It could be some weird USB issue. Have you disconnected everything and just using external keyboard?
 
ok, only battery, speakers and fans plugged in, i get chime but no reaction to the reset key combination. tried both usb ports and the keyboard works on other systems.
 
no I dont. Would you say that the fact that I am unable to perform PRAM reset indicates bios issues? Is there a way I could confirm it prior to bios replacement?
 

dukefawks

Administrator
Only way to find out is to flash it. If you do make sure you have a backup first! Go get a TL866 if you are planning on doing more repairs in the future.
 
Ok. I got the programmer. I also got the preprogrammed bios chip. I swapped the chips and it is better but extremely slow on boot. I got it up once with a spare disk I have for this model. On clients disk it only let me get to the login in safe mode - and only happened once. Tried booting from Sierra usb stick - it loads the bar fully which takes around 30 min and just stays there. I run ASD and it failed only on the engine as I am guessing i will need to program in the SN. Any advice how to proceed?
Kind regards
 

dukefawks

Administrator
ME region is fucked up. See how well these Ebay chips work?

Upload the original BIOS here and I will fix it. Also provide the original serial number of the machine.
 
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