820-00165 no PP3V42 or PPBUS

[tlough75]

Good morning. I have an 820-00165 that has no green light on the charger, PP3V42 is .43V and PPBUS is .5V. I checked PPDCIN which is 18v and pin 4 of Q7010 which has 6.8V on it so I assume that is working based on measurements taken from another board. I also checked and do not have any short on PPBUS so I am wondering if U7100 is causing my issues.

 

[2informaticos]

Post basic voltages for U7100 and U7090...

 

[tlough75]

U7100:

1 - 0V 15 - .01V
2 - 18.27V 16 - .003V
3 - 4.878V 17 - .003V
4 - .244vV 18 - .003V
5 - 0V 19 - 5.077V
6 - 0V 20 - 5.077V
7 - 0V 21 - 0V
8 - 0V 22 - GND
9 - .033V 23 - .004V
10 - .252V 24 - Started at 3.3V but then kept drifting down
11 - .252V 25 - 4.77v
12 - .252V 26 - 17.8v
13 - .089V 27 - 18.07V
14 - .250V 28 - 18.07V

 

[tlough75]

15 - .001V
16 - .003V
17 - .003V
18 - .003V
19 - 5.077V
20 - 5.077V
21 - 0V
22 - GND
23 - .004V
24 - Started at 3.3 then drifted down
25 - 4.77v
26 - 17.8v
27 - 18.07v
28 - 18.07v

 

[tlough75]

u7090:

1 - .59v
2 - .251v
3 - 1.492v
4 - .462v
5 - gnd - 0
6 - 17.65v
7 - N/C
8 - 17.65v

 

[tlough75]

Sorry for posting all, I didn't want to miss anything

 

[tlough75]

something has to be shorting PP3V42 to GND.

 

[tlough75]

So I forgot There were a few corroded components by the SMC as well as two broken traces, to the two lines to the right of the SMC. I replaced all of the baddies and repaired the two broken traces and now have PP3V42, PPBUS_G3H, CPU VCORE is at 1.8v. The only problem now is no image or backlight

 

[2informaticos]

Do you get USB activity?
I recommend to reball SMC, if you noted corrosion near it.