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820-3437 Dies When Battery Connected

brunomotter

brunomotter

Member
Hello guys. This is a third party repair for another store that I'm doing here. The board has been UC on the other store before coming here, so probably it got liquid damaged and that's why they cleaned it. The symptom is that the machine works without battery, charger goes green/orange and works well. As soon as I plug in the battery it dies. No light on charger and the charger itself gets disabled by the board and only works again if I unplug and plug it in the wall again without battery connected. Verified R7151/7152 and both are ok. Replaced ISL and reballed SMC. Same results. What else can I check?
 
brunomotter

brunomotter

Member
I did not measure PPBUS before, but it's giving 15.91V(!!!!). Replaced Q7130, voltage dropped to around 10V, still very high for this board and the MOSFET gets REALLY hot! Maybe ISL got damaged also because of the bad FET?
 
brunomotter

brunomotter

Member
Replaced. Same thing. I think Q7130 fried again. PPBUS_G3H acting like a roller coaster and board does not turn on.
 
brunomotter

brunomotter

Member
Replaced both. Board turned on again, but Q7130 is boiling hot and PPBUS_G3H is above 12V and fluctuating up and down like hell.
 
brunomotter

brunomotter

Member
Trace from Pin 24 of U7100 to Pin1 of Q7130 was broken. Ran a jumper and now I have stable 8.59V on PPBUS_G3H, but the board won't power on anymore.
 
brunomotter

brunomotter

Member
Will try measuring, as I don't have an oscilloscope.

PCH_CLK32K_RTCX1 - 0.413V
PCH_SRTCRST_L - 3.326V
PPVOUT_S0_PCH_DCPRTC - 1.318V
PPVRTC_G3H - 3.326V
RTC_RESET_L - 0.989V
 
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