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820-3115 - component R6990 frying

Palhano

Palhano

Member
Logic board in good condition.

I don't have the PP3v42 and PPBus line. then I noticed that R6990 was burned. I looked for short in the lines and didn't find it. I changed the R6990 and D6990, same problem, R6990 fries (solder is soft). Removed the R6990, I get 17v on pin 1 (PPDCIN_G3H).

Any suggestions?
 
2informaticos

2informaticos

Administrator
Staff member
Check diode mode to ground at C6990/9; C6990 is the first suspect there.
U6990 can also be the culprit.
 
Palhano

Palhano

Member
Replaces R6990 and D6990 again, R6990 stopped frying! I have 17v on pin 3 of the D6990. But I don't have the 3.42v.

I tried to change the U6990 and it didn't work.

Diode mode:
C6990 - pin 1 - 0.580
C6999 - pin 1 - 0.370
 
Palhano

Palhano

Member
I switched the C6999 and U6990, for a few minutes I had 3.49v, a little higher, but no LED on the MagSafe. Now I don't have it again. I checked the component solder. I also tested with another DC card, same thing.

pin 2 - 3.75v
3 - 7.5v
4 - 16.5v
6 - 0
7 - 16.5v
8 - 3.75v
9 - 0
10 - 0
 
Palhano

Palhano

Member
I found that when I have the C6990 on the board, the somo 3.42 disappears! I changed it, but same problem.
 
Palhano

Palhano

Member
I've already changed the U6990 3x. I soldered the C6990 without using air, so as not to mess with the U6990, same problem. Without it I have 3.49v, PPBus 12.2v and no MagSafe LED.
 
Palhano

Palhano

Member
Yes, I tried with another C6990. I thought it might be the hot air messing with the U6990, so I soldered it with the iron. Same thing.

Sorry, forgot to inform. Yes, I changed the C6991/6.
 
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