MacBook Pro 2011 820-2936-B won't start

[bmwpowere36m3]

Found Wife's 13" MBP one night with the case swollen, opened screen and trackpad bulged out. Immediately thought battery had died and swelled. Sure enough that was the case. However after removing battery and plugging in, it worked fine. Ordered a new battery, put it in and it seemed to be working fine and charging. Few days go by....

Now the laptop won't start, no battery indicator, nor green light on magsafe. Searched around, found some info on "one-wire circuit" and started checking the logic board.

I don't see any damage, maybe a few spots that have a reddish/brown discolored on some of the gold pads. Maybe light corrosion from possible gas leaked from damaged battery.

Logic board is a 820-2936B and I'm getting no power on: PPBUS_G3H or PP3V42_G3H. I'll double check U6990, but I had voltages of 16.5 input, 14.5 input with resistor and 3.8 V on FB IIRC.

[piernov]

Re: MacBook Pro 2011 820-2936-B won't start

Take board out of the chassis, disconnect everything from the logic board except DC-in board and fan and plug in Magsafe. See if that makes any difference.

If not, measure resistance to ground on PP3V42_G3H.

[bmwpowere36m3]

Re: MacBook Pro 2011 820-2936-B won't start

Take board out of the chassis, disconnect everything from the logic board except DC-in board and fan and plug in Magsafe. See if that makes any difference.

If not, measure resistance to ground on PP3V42_G3H.

Those observations were with just the logic board, ram, fan, DC board and plugged into charger.

PP3V42_G3H is 0 ohms to ground

[piernov]

Re: MacBook Pro 2011 820-2936-B won't start

0 ohm to grounds means it's fully shorted to ground. There's a dead component somewhere on the line. Inspect visually the board especially around the spots where PP3V42_G3H goes, and if you can't spot anything, inject 1V with a lab PSU and find the component that's heating up.

[bmwpowere36m3]

Re: MacBook Pro 2011 820-2936-B won't start

0 ohm to grounds means it's fully shorted to ground. There's a dead component somewhere on the line. Inspect visually the board especially around the spots where PP3V42_G3H goes, and if you can't spot anything, inject 1V with a lab PSU and find the component that's heating up.

I'll have to figure out how to supply 1V, besides purchasing a lab PSU. Are we limiting the inject to certain amperage?

Seems freeze spray or canned air can help identify the heated component.

[bmwpowere36m3]

Re: MacBook Pro 2011 820-2936-B won't start

Got a power supply to test with and applied 1.2 V which drew 2A on PP3V42_G3H and C6999 is vaporizing denatured alcohol of board.

[piernov]

Re: MacBook Pro 2011 820-2936-B won't start

Yep so you found the culprit. C6999 has to be replaced. (not just removed, it is a critical cap since it filters and stabilizes the output of PP3V42_G3H regulator)

[bmwpowere36m3]

Re: MacBook Pro 2011 820-2936-B won't start

Replaced C6999 cap, PP3V42_G3H is 3.47 VDC, green light comes on, fan spins. Assuming good to start putting together?

[piernov]

Re: MacBook Pro 2011 820-2936-B won't start

Sounds good yes.