820-2883 no green light

[Yoel Ren]

Came in with many dust at the back of the logicboard, magsafe showing dim green light
R6905 is smoking when connected to magsafe,there’s hole on d6905 too
I have replaced r6905, unfortunately i dont have d6905 so i used u6901 from donor board (820-2879), when connect magsafe i have brief green light but after that, suddenly i don’t have any green light (not even dim green light), there’s no voltage at pp18v5 fuse, so this looks like mosfet issue , is q7050 the problem?

 

[2informaticos]

Check diode mode at C6990/99 and F6905.
Be sure the fuse is still good.
Also post exact ohm value R7010/11 and R7001/98.

 

[Yoel Ren]

Diode mode on c6990 0.189
C6999 0.292
Fuse resistance is 0.3 ohm so, good
R7010 7.3kohm
R7011 7.1kohm
R7001 55kohm
R7098 106kohm

 

[2informaticos]

" on c6990 0.189 "
No good this...

Remove C6990 and check again.
If still low, replace U6990.

 

[Yoel Ren]

C6990 and u6990 replaced, diode mode of c6990 is 0.409 now.., but still no green light

 

[Yoel Ren]

Pp18v5 isnt even present, does this mean q7020 is bad?

 

[2informaticos]

You didn't post diode mode at F6905.

Check if board works with fake charger, or lab power supply.
In such case, leakage issue is bypassed.

 

[Yoel Ren]

0.411 diode mode
nogreen light with fake charger

 

[2informaticos]

But do you get voltages on the board???
Is better to use a lab power supply, connected through 85W cable.

 

[Yoel Ren]

yes, i got 16.5v at ppdcin fuse..

 

[2informaticos]

Only that???

"voltages on the board???"
I expected more readings; at least 3V42 and PPBUS_G3H...

Post U7000 voltages; pins 1, 2, 3, 9, 12, 14, 15, 17, 19, 20, 27.

 

[Yoel Ren]

sorry i was in hurry when replying this msg.. here’s the reading..
Ppbus_g3h 0v
Pp3v42 : 0v
U7000 pin 1: 0v
2: 16.4v
3: 3.9v
9: 0v
12 0v
14 0v
15 200mv
17 0v
19 5v
20 5v
27 9.3v

 

[2informaticos]

Post exact resistance (ohm mode) between pins 17/18 and 27/28 of U7000.

"27 9.3v"
This is really strange.
Check first Q7000; also Q7001 if still low...

 

[Yoel Ren]

Resistance is 3.5 and 20 ohm,
So normal
After replacing q7000 and q7001, here’s the reading
Q7000 pin 1 : 6.2v
2 3 4 : 16.5v
Q7001 pin 1 2 3 4 0v
Pin 5 16.5v

 

[Yoel Ren]

Now, with original magsafe, i got dim green light, but no voltage at dc in fuse, maybe we can fix the leakage issue, then solve the pp3v42 after that..

 

[2informaticos]

Fake charger bypasses the leakage, use it at this moment; untill find the problem.

Q7001 looks bad, or incorrect model.
Be sure to use P-channel MOSFET...

 

[Yoel Ren]

i replaced q7001, and i have 17.5v at pin 1-5
i have replaced u7000 too, here's the reading with fake charger :
1 : 0
2 : 16.5v
3 : 3.9v
9 : 0
12 : 0
14 : 0
15 : 0
17 : 0
19 : 5v
20 : 5v
27 : 17.9v

 

[2informaticos]

"12 : 0"
Puff, 3V42 also missing.
Post U6990 voltages...

Don't you get any voltage at PPBUS_G3H now?

 

[Yoel Ren]

no ppbus voltage
u6990 pin
1 : 1.6v
2 0v
3 9.3v
4 cycling up to 200mv
5 gnd
6 0v
7 nc
8 300 mv
9 gnd

 

[2informaticos]

Check diode mode at C6990/99.
Replace R6905; maybe D6905 too...