820-3332 short PPBUS_G3H

Kyle93

Active member
820-3332 no liquid damage. Original problem apple progress bar freezing about a quarter of the way. Resoldered U8900 and booted successfully. When turning on a second time board suddenly died and now there is a 0.10 short on PPBUS_G3H and voltage only 1.8V

Nothing is getting hot on the board. Removed U7000 to rule out but still short on PPBUS_G3H

Removed F7040 and F7041 and short is on pin 2 of each.

What to check next?
 

2informaticos

Administrator
Staff member
If you get same 010 on L8930/60, then Q8930 is burnt.
Supposedly bad solders on pins 20/29, 19/30 of U8900, or damaged R/C bootstrap.
 

Kyle93

Active member
2informaticos was right on. Replaced Q8930 and short was gone PPBUS_G3H back to 12.60V with just ac adapter.

When trying to power on with battery connected left fan was barely spinning for a few seconds and then died again. Same short is back again.
 

Kyle93

Active member
Replaced Q8930 and U8900. Short gone and board powering up normally but now have a black screen. U8900 is soldered properly. Anything else to check before replacing U8900 again ? All parts came off donar
 

Kyle93

Active member
GPU was working fine when first arrived since apple logo appeared, just wouldnt fully load OSX.

PVCORE_GPU is 0V. Will update when new U8900 arrive
 

JohnB8812

New member
You bridged something more than likely which shorted Q8930 and likely killed theGPU. You must replace all fets and U8900 when something like that happens on the off chance it survives.
 

MOMOH

New member
Have you confirmed you have image ? I Have the same case , but got mine resolved
 
Last edited:

2informaticos

Administrator
Staff member
"GPU was working fine when first arrived"
That is not a reason to assume is still better after Q8930 was shorted two times.
You can change required components and pray (a lot) before power it on...
 

Kyle93

Active member
Which specific fets do you need to replace? Replaced U8900 but still 0V on PPVCORE_GPU. 0.009 short on diode mode. Should GPU be heated next?
 

2informaticos

Administrator
Staff member
200 diode mode on GPU VCORE is to high.
009 is good value I suppose.

Change at same time U8900, Q8930/31/61.
Be sure R/C8930, R8960 and C8965 are all good.
Also be sure to have good traces and solders.
 

Kyle93

Active member
Made a typo with measurement.

its actually 0.020. Is that a normal value or should all requested parts still be changed out?
 

Kyle93

Active member
Everything changed and checked.

0V still on PPVCORE_GPU but 4.75V on C8965

Turns on and chimes but no backlight or image.
 

2informaticos

Administrator
Staff member
Is gets enable and correct power on all pins, U8900 should generate GPU VCORE.
Maybe knocked off component, broken trace, bad solder.
Re-check all the job.
Post again diode mode on L8930/60.
 
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