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[SOLVED]820-2936-A no power

K

Kalemaroni

Member
Hi all, I am new to board level repair but working hard on the learning curve and would like to give many thanks to Louis for his videos.

I bought an 820-2936-A board and had green + orange light with magsafe and battery plugged in. I then decided to write down some values of U7000 to cross reference with another board I was working on but I think I shorted pins 2+3 and now I get no light at all! I have since been made aware of the existence of, and that I should've used, the test points to measure voltage not the actual pins so as not to cause the damage that I most likely have caused! In the meantime I'd be very grateful for some assistance in recovering this board.

Some measurements that may prove helpful in assisting me:

R6929 0v
C6908 3.4v
U6901 3.4v on PP3V42_G3H but 0v on all other pins.
U7000 DCIN (pin 2) 16.4v
U7000 ACIN (pin 3) 0v
​​​​​​​
Many thanks in advance for any responses.
 
A

aprendiz

Moderator
Seems is not soldered properly, pin 2 was 16.4V before you replace the ic, redo the soldering job and check value for R7005....
 
K

Kalemaroni

Member
I have tried 4-5 different ISLs now, I've cleaned up the pads and re-tinned each time and I'm getting the same results - very frustrating! I'm getting a green light at least now but still pins 1, 15-21 and 26-28 are reporting bad values.

I don't know if maybe I'm not doing it right or if the chips are bad - I don't have the experience to tell. I have watched numerous videos on the process, I have tried letting the chip just fall into place as the solder melts, I've tried pushing it down firm, and I've tried letting the tweezers rest with just a little pressure but same results each time. I've cleaned up the joints with flux and solder afterwards and checked as much as I can that there are no bridges.

Is there something else that could be causing the problems or do I just need to get this chip on right? Is it possible I've burnt something out on the board and is there a way to check for this if so?
 
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