820-00923-A stuck at 5V

Fanfwe

Member
Hi,
I got a liquid damaged board that doesn't manage to get 20V from the charger.
From the corroded areas, it is pretty clear to me that the top left CD3215 (UB400) is, among all 4, the one that's causing trouble.
Another hint is that I get power loop on 3 of the ports, and on the last one, I get a constant 5V instead, and of course, that port is the one managed by that chip.

I had noticed that the test pad for the 3v3 LDO on the edge of the board was corroded enough to have a trace cut, and I got that fixed, but it didn't help.
Next I decided to replace the CD3215, and that also didn't fix it.

Probing a little more, I can see that I'm missing the 1V1 LDO output from that chip (PP1V1_UPC_TB_LDO_BMC). I checked resistance to ground, and there is no short.
All other LDOs are there.

Not quite sure what to do from there. Any hint on something else that could be required before this LDO gives 1v1 ?

One more question. Is it possible to somehow inject 20V straight into the board in order to, at least, check that the rest of the board is good and will boot once the CD3215 issue gets resolved ?
 

2informaticos

Administrator
Staff member
"Is it possible to somehow inject 20V straight into the board in order to, at least, check that the rest of the board is good and will boot once the CD3215 issue gets resolved ?"
Is possible, you can inject even 220V AC; depends what you have available ;).
Seriously, I do NOT recommend to inject any voltage!
You will not get any (good) result doing that...
 
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