tcampbell34
Member
This board was liquid damaged but not very badly. Some corrosion around U6903 and PP3V3_G3H_RTC was shorted to ground. I removed U6903 but it was still shorted so I injected voltage and found U7800 was getting hot. I removed U7800 and the short was gone. I replaced both U6903 and U7800 from the same model donor board, and I now get 3.3v on PP3V3_G3H and 12.3v on PPBUS but only about .450v on PP1V8_SLPS2R. I have 0v on the other coils around U7800 also. I assumed the U7800 I got from the donor was bad so I removed it, reballed it, and put it back on the donor board, just to see if I would get 1.8v on PP1V8 and I do get that voltage on the donor, so I don't think this U7800 chip is bad. I have reballed it again and re-soldered it to this board and now back to about .350v-.450v on PP1V8 so something on this board appears to be pulling it down. I do get 20v on this board so idk if that rules out an issue with the CD3217's and T2 or not. Any idea what to check?
