820-2879-B no green light

[Kalemaroni]

This board gets no green light from the charger. PP18V5_DCIN_FUSE goes from 0.3v to 1.8v then back down again. Q7085 gets quite hot. I replaced it but it made no difference. Advice on how to proceed would be greatly appreciated.

 

[dukefawks]

I would think there is a short on one of the PPDCIN rails or PPBUS.

 

[Kalemaroni]

Thanks Duke. There was indeed a short, in fact 2 shorts, at PPVBAT_G3H_CHGR_REG on L7030 and PPDCIN_G3H_CHGR on Q7030.

After replacing both I now get just a green light but no orange and no start up. PPVBAT_G3H_CHGR_REG is still shorted even though I replaced L7030 with one that wasn't shorted on the donor board. When I removed it I checked both pads and no short so surely it was this component causing the short to the line? Does this component not like heat or something?

 

[dukefawks]

Can you explain to me how L7030 can cause a short to GND?

Remove F7040 and see on which side the short to GND is. It is probably on pin 2 the system side. Inject voltage there, start low and monitor current draw. At 2-3 amps something should be heating up that is causing the short.