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820-00875 PPBUS_G3H boosting after liquid damage

nik1981

nik1981

Member
Hi, I have a 00875 thats had liquid damage over the U7650 side of the board.

After going through the UC, the laptop started from the battery and got into the OS but I walked away and came back to it turned off. Not sure if the battery is drained or something else.
I don't have a spare battery to test with.

20.4v going into the board from the genuine charger.
PPBUS_G3H is boosting to 12.93v and then dropping to 3.4v repeatedly
s5_pwrgd is boosting to 5.1v then drops to 3.2v and then drops to 0v.. it then starts over again.

I get a fan twitch and the CPU is getting warm

Apologies if I should have given some basic info that I've missed in this initial post.

Any help would be appreciated
 
2informaticos

2informaticos

Administrator
Staff member
Start then in SMC bypass mode and check all power sensors output, pages 43-45.
Be sure first to have correct AVREF_SMC voltage.
 
nik1981

nik1981

Member
It turns itself off after a few seconds. Gets into the OS but thats about it before the power cuts off
 
nik1981

nik1981

Member
SMC bypass doesnt seem to work either now. Fan spins full for about 2 seconds but nothing more and no screen.
 
2informaticos

2informaticos

Administrator
Staff member
Try UC again.
You can check one power sensor every time the machine turns on.
2s should be enough for one reading; no need to login to OSX.
 
2informaticos

2informaticos

Administrator
Staff member
Yes, check all them.
Now is strange if doesn't start on SMC bypass too.
But check them, maybe help to make an idea.
 
nik1981

nik1981

Member
I'm struggling to be able to accurately check them.. They are all on the opposite side of the board. I need about 6 pairs of hands :(
 
nik1981

nik1981

Member
C5409 SMC_CPU_HI_ISENSE = 30MV

C5680 SMC_CPU_VSENSE = 0.5-0.9 BOOSTING

C5605 SMC_CPU_ISENSE = 0V

C5615 SMC_GT_ISENSE = 135MV

C5682 SMC_GT_VSENSE = 0MV

C5691 SMC_SA_IMON_ISENSE = 359MV

C5631 SMC_SA_ISENSE = 0MV

C5523 SNC_3V3S5_ISENSE = 0.5V

C5518 SMC_3V3SSD_ISENSE = 0MV




C5690 - SMC_CPU_IMON_ISENSE = 0V

C5469 SMC_TPAD_ISENSE = 0V

C5508 SMC_1V2S3_ISENSE = 0V

R5489 SMC_PBUS_VSENSE = 2.1V

C5489 SMC_PBUS_VSENSE = 2.1V

C5438 SMC_BMON_ISENSE = 0V

C5533 SMC_3V3WLS_ISENSE 0V

C5459 SMC_LCDBKLT_ISENSE = 0V

C5528 SMC_3V3LCD_ISENSE = 0V

Hopefully theres something here that looks odd
 
nik1981

nik1981

Member
It sometimes works and runs for a while, other times it starts for only 2 seconds. I?ll be away from work until Tuesday now but will carry on when I?m back. Thanks for your help so far :)
 
nik1981

nik1981

Member
I've put the board back through the UC, PPBUS_G3H is now sitting at 0v.. So I'm guessing whatever poor connection there was has vanished now.
 
2informaticos

2informaticos

Administrator
Staff member
There should be broken trace, or solder.

Try good flux and heat SMC and CPU.
This will not solve broken trace, but give it a try.
 
nik1981

nik1981

Member
I'll flux and heat the SMC with 559 flux and give the cpu a little heat without flux (I'm assuming you didn't mean flux the CPU also)
 
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