820-00928-A powers on - no picture

DeDaMrAz

New member
Hi all

I have a frustrating 3000$ fully specced problem on my hands and I need some experience shared to help me fix this problem.

Above mentioned MacBook came for EFI password removal that legit owned brought in, I've unlocked it and the owner was able to log in and all was good (friend - favor...). After 4-5 days he got back and wanted me to re install OS on it and after backing up and wiping SSD I rebooted it to a black screen. I got all major voltages: 5v, 3v3, G3HOT is (12v3), 1v05, 0.95 1V8 you name it.

The thing I am missing now is back light power enable signal. No USB activity and no picture on external monitor. All PM_SLP lines are present,CPU_PRWGOOD is 1V, CPU VCORE is 0V80 to 0V95 and only thing of "concern" is that south bridge is slightly warm to the touch ( i don't remember it being that way!) Also, laptop powers on and can be powered down via power button, battery is charging in normal fashion (20V, amperage varies)
I can provide any relevant info as I am stuck with this board for months now, waiting for a spare board for parts. Board view and schematics are present and helpful. No water dmg, no physical dmg.

Any help, suggestion or hint is much appreciated.

Let me just mention that I am not new in this type of work, just this model is a first one that I am working on so lack of experience is a factor - so I am reaching out for it :)

Thank you and I will really appreciate any help.

Regards.
 

DeDaMrAz

New member
Also due to that relative heating of SR2NH (QMS180) chipset I got a "new" one but I am more willing to exhaust all other relevant measurements before replacing that chip.
 

2informaticos

Administrator
Staff member
Check for solders, traces and knocked off components around SPI chip.
Did you try PRAM reset and SMC reset?

If you deal with Apple stuff, get Medusa programmer; it allows you to properly change BIOS content.
 

DeDaMrAz

New member
No, not on regular basis but thanks for the hint, will try and post results.

Got couple of programmers for 25 series eeproms so I am good there, thanks.
 

2informaticos

Administrator
Staff member
I mean Medusa can change serial number and fix checksum after.
It properly clean ME region, which no other programmer and software does it.
You can also disable GPU on 2011 boards with it.
 

DeDaMrAz

New member
PRAM or SMC reset didn't do anything :/ Even replaced the BIOS chip with a new one a programmed it with original locked file externally - no dice!
 

DeDaMrAz

New member
PROGRESS!!!

Removing life boat connector gave me picture/flashing question mark folder, managed to run diagnostic and got VDH002 error (with connector back on).

Never got this far, so any idea would be highly appreciated, thanks!
 
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