820-2915 - No liquid DMG - Generic charger fried it.

[MrPyle]

I've got tunnel vision on this repair ....

Customer plugged in a generic charger, which was bad, into 3 different macbooks, all of them died. Two of them I repaired ... still working on the third. No liquid damage. And no visible board/trace damage. Just the few components visually blown on the top.

Found D6990 and U6990 were blown. R6990 was bad as well as R7005 and U7000. Replaced all of that and a couple of caps, C6991 and C6994 right next to U6990.

Plug it in ... get a green light for about 5 seconds. Then no light, once in a while it comes on for a second or two. U6900 pins 1,4,5 - 2.95v. U6901 - Pins 1,2 - 3.2v .. pin 4 - 3v, pin 5 - 3.42v.

SMC reset is at 3.4v.

Q7030 - Pin 1-3 12.3v .. pin 4 12.7v .. pin 5 18.2v.

Found 18.6v coming in has a voltage drop every 5-6 seconds. Usually 1.5-2 volts on the meter. Which of course causes the 16v to drop as well. Fuses check ok (found one acting like a resistor on one of the other repairs).


At this point, any tips would be helpful. Not exactly a noob to board repairs, but not a veteran either. Just got into mac's as well. Will be back in the shop Thursday, but the above is what I recall at the moment.

 

[dukefawks]

First thing is to get the green light stable. Start with a known good magsafe board. Then go on to check if 3V42 is present and stable. SMC RESET seems good, so then check AC_OK from ISL6259.

 

[MrPyle]

A quick look this morning over some rails. Already tried a couple known good magsafes.

PP5V_S5 - 5.01
PP3V42_G3H - 3.41
PPBUS_G3H - 12.28
SMC_BC_ACOK - 3.41
SMC_BC_ACOK_VCC - 2.97
ADAPTER_SENSE - 2.93
SYS_ONEWIRE - 2.93
PP3V3_S5 - 3.33
PP3V3_S4 - 3.33

PM_SLP_S4_L - 0

PPDCIN_G3H - 18.7 (DROPS 1-2 VOLTS/5-6SEC)
CHGR_DCIN - 18.27 (DROPS 1-2 VOLTS/5-6 SEC)
PPDCIN_S5_P3V42G3H - 16.8 (DROPS 1-2 VOLTS/5-6 SEC)

Short to ground causing the drop? Noticed U1800 is warm, but not hot.

 

[dukefawks]

PPBUS at 12.3V means SMC is not running. I assume you have no green light? I'm afraid this may be a dead SMC. Also U1800 should not get warm at this point. I bet 3V42 bus went high killing SMC and PCH.

 

[MrPyle]

Sort of what I was thinking. Shouldn't be warm at all in an off state. And yea, no green light. Two out of three isn't bad I guess. Still can't believe they plugged the same charger in 3 diff macs. Darwin award!