820-00923 3 problems

waterchill

Member
Hi guys,

so I have this macbook here and it have 3 problems. History not available, no water damage.

1) Touch bar not working, changed with known functional touch bar
2) Critical software update
3) Graphic errors on display and external display, no errors when in safe mode

According to the repair wiki I have unplugged all devices and started macbook with same errors. It is possible to install macos, but after booting there is still message with critical update.

PP1V8_Sleep3_Buck3 = 1,8V

In my opinion the cpu/gpu is faulty, tried to reflow but same error. Before changing to new cpu, would like to hear some opinions about this. Someone attempted a repair in this area please look pictures. The coil is already replaced. Actually I'm stuck with this repair.
 

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2informaticos

Administrator
Staff member
Bad internal/external video at same time, points to iGPU issue.
Coorect image in safe mode (iGPU driver not loaded), confirms that.

Did you checkk all these?
 

waterchill

Member
I followed all these steps without result. Actually I desoldered the PMIC for reaballing, but I cannot find a stencil for this. What stencil do I need for this? It has 12x13 points
 

waterchill

Member
So I have reballed the PMIC but now ssd, keyboard and touchpad not detected. I have replaced with new PMIC but same problem. I believe after reballing something gone wrong and was shorted. Looks like PP3V3_S4 is shorted to ground. Now I have to find this short first...
 
Last edited:

waterchill

Member
I cannot find short. One area is getting hot but there is nothing. Any suggestions?
 

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2informaticos

Administrator
Staff member
What is the ohm resistance of that "short"?
You may have problems inside the board, between copper layers...
 

2informaticos

Administrator
Staff member
That is pure short.
Be sure to use powerful cables and set PSU limit to max first.
Start injecting with 1V...
 

waterchill

Member
Now I have took bigger cables, but still no component found with short. Went to 3,6V with 3,4amps. Some traces are getting warm and the whole area in the board but cannot find a component. I injected on the soldering Point TP1
 
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