820-00163, R7005 & R7020 Both Blown

[SMMRepair]

Hey guys, I'm working on a customer unit (820-00163) with issue reported as "no power, no light". I quickly realized R7005/R7020 (by 3787 schematics reference) were both toast. As I'm having to sort of work blind on this one and with limited parts boards for this model, I wanted to post a few quick questions to help myself out a bit:

1. Since R7005/R7020 were both blown, I'll assume Q7010 is fucked and will be replacing it. Would it be wise for me to replace U7090 as well, to be safe? Or can I suspect that R7005/R7020 did their respective jobs and U7090 is probably OK? I know Diodes are pretty robust, but what about D7005? With limited parts boards, I want to make sure I replace all damaged components first-go, but without schematics it's a bit tougher (no schematics = no part numbers to compare against other boards, so can't pull from different model boards easily).
2. Based on R7005/R7020 being blown (with zero liquid indication anywhere on the board), can I assume anything about the customer's use of a faulty/generic charger? If so, I'd like to mention to them that as a possible cause (and so they won't use the same one again with a newly-repaired board, of course).
3. Is the 820-00138 or 00163 schematic out yet? Just curious. Sort of tedious working without them, but that's the nature of the business I imagine.

Thanks again in advance; always get great help here.

 

[dukefawks]

Yup this is a garbage charger problem. ISL6259 is dead and R7005, R7021/22, R7051/52 should all be checked. The rest is probably ok, apply power and see if it works.

 

[SMMRepair]

Great, thanks Duke. I'll get this one taken care of tomorrow and will post an update to confirm. Thanks for confirming the shit-charger suspicion; always good to be able to bring that up beforehand so if the same thing happens we'll have a foot. Thanks, Duke!

 

[SMMRepair]

Hey Duke; I got the ISL replaced along with R7020 and R7005. I checked the other resistors mentioned (7121/7122, 7151/52) and they're all still measuring fine. When I plugged the charger in, R7020 blew immediately. When I removed it and checked diode readings on both pads and I get OL on pin 2 and 2.04 on pin 1. Would this mean Q7010 is killing the resistor? Working blind on this thing sucks, so I appreciate the help. Thanks!

 

[SMMRepair]

OK, got this one figured out. I swear the secret to figuring something out is to post about it so your brain re-thinks it to type, then you can't help but to think about another variable.

Anyway, I found that PPVIN_G3H_P3V42G3H was shorted. Without proper schematics, I had to just look around and think. Checked all surrounding caps and U7090, but nothing looked shorted and short remained when I pulled everything there. Decided to flip the board over and see if any caps on opposite side (in same area, through-board) looked nasty. Sure enough, found 2 caps and one was brown and obviously broken-down/shorted. Pulled it, short gone, replaced and I get green light without smoke now.

Thanks, Duke! I'll confirm once board passes all diagnostics, etc.