820-00138 Works Fine with External Display. Inter display Freezes

[Mac Repairs]

Hi All,

This MLB no liquid damaged and very weird behaviour.
It boots to logo in screen and freezes. When you connect to external monitor, both internal and external displays work fine. works fine with
only external as well. but it freezes with internal display only. tried to different screens and also putting the MLB to known working top case and screen still same. I replaced all CPU mosfets with new mosfets still the same. Any advice really appreciate.

 

[2informaticos]

Tried NVRAM?

Shouldn't be the problem, but discard a software issue.
Test with other macOS, USB or different SSD.

 

[Mac Repairs]

Hi Thank you for your reply.

I tried NVRAM as well as NVRAM, clean me , new bios using medusa. Tried with external USB and different SSD. Same issue.

 

[2informaticos]

Really weird issue, as this board doesn't have dedicated GPU.
Doesn't even has separated iGPU power supply.
But something happens with iGPU I suppose.

Did you change all U7310/20/30?
I hope not with same FDMF6808N...

 

[Mac Repairs]

Yes it is weird issue that I never faced. I already replaced 3 FDMF6808N with new chips from mouser. still same behaviour.

 

[2informaticos]

What chip did you use?
New FDMF6808N doesn't exist.
Mouser shouldn't have it in stock even; considering is serious seller.

 

[Mac Repairs]

Wow. if that is the case I'm lucky as I bought them August 2019. Anyway I replaced these 3 chips and seems they are woking fine as I get 1.7+ V , on coils.
Is there any relation other than iGPU between screen connector and external display?

 

[Mac Repairs]

Hi, Finally I figured the fault and fixed. Thought to share the repair as it useful for others.
Issue was with Q2010, LCD HDP inverter. DP_IG_A_HPD_L signal was missing. I pulled Q2010 and found pad was completely burnt. Had to run a wire. all good. So this is solved. I have other one 820-00163 which I'm going to open a new threat. Thank you very much for your support.

 

[2informaticos]

Thanks for feedback, as that is very strange issue.

BTW, you didn't say what chips used to replace on CPU power supply.
Keep in mind, REAL new FDMF6808N didn't exist ever, for large public; it was Apple property.

 

[Mac Repairs]

Hi As I said these FMDF6808N chips I bought them Aug 2019. I used them and had 6pcs. I didn't know that they are not available. How ever they are still available in Aliexpress.

 

[piernov]

I've never seen FDMF6808N available from any official suppliers. Mouser has FDMF6708N and FMDF3030 which are compatible though.
The stuff on Aliexpress is never new, pulled from dead board so of course it must not be used in this case.

 

[Mac Repairs]

Correction. You are right. My chips are not FMDF6808N, its 6708N.