820-00928 PP1v8_sus missing

[rvanpruissen]

Charger switches to 20v. No PP1V8_SUS, not a short.
PP3V3_S5, PM_SLP_SUS_L and PP5V_PMICLDO are all there, but no output on L8020.

Has significant water/beer damage near PP1V8 feedback resistor area. All of this was restored.

Working from a 820-00239 schematic and 820-00281, they seem close enough.

 

[2informaticos]

Check value for R8020/21/25 and their traces.
Be sure XW8020/21 bridges are OK...

 

[rvanpruissen]

Although the area looks a bit messed up, these resistors and XW's measure fine. I'm thinking there might be another input on u7800 causing this behaviour, but there's a confusing amount of inputs on this chip. Any ideas?

 

[2informaticos]

It may have firmware, I don't exactly know.
As per schematic, PM_SLP_SUS_L is its enable signal.
You've told is present, so the problem should be U7800, or corrosion around L8020; check resistors, traces...
Reflow U7800, maybe not properly soldered.

 

[rvanpruissen]

Ok, I've sent it back. Thanks guys.