[SOLVED]820-3476 PPBUS_G3H 14v. Have charger green, orange light, fan spin, and chime.

[computercaverva]

[SOLVED]820-3476 PPBUS_G3H 14v. Have charger green, orange light, fan spin, and chime.

I have an 820-3476 with an unusually high PPBUS_G3H at 14 volts. I've checked R7121 and R7122, both are fine. Before I started having trouble with PPBUS_G3H I had a blown U7700 that I replaced. Upon turning on the system and checking PPBUS_G3H, I found it was only outputting 2v, shortly after the new U7700 melted, destroying the traces connecting U7700 pins 9, 10, and 11. I rebuilt those traces, replaced U7700, and replaced the ISL--had to repair damaged pads on pins 5 and 10. I'm not sure what could be causing the high PPBUS_G3H as everything along those paths seems to be right.

 

[dukefawks]

Feedback circuit issues, R7051/52 and/or traces or possibly bad Q7130.

 

[computercaverva]

Thanks, I'll check those out when I get in tomorrow. Much appreciated.

 

[computercaverva]

Was definitely Q7130, thanks a ton. Replaced those resisters as well, they were only slightly out of spec. but at this point it's more worth while to be sure.