[SOLVED]820-3209 - Chimes, no backlight, no image, no keyboard.

[gcain]

System chimes.
No Backlight.
No Image.
No Keyboard
No Trackpad? (can't really test)
Fan runs high.

Lots of corrosion around C4020, C4021, R4052 (WLan).

Replaced and leaned it up but no change in behaviour. I can hear a chime but cannot perform a PRM reset, even with a known good keyboard and trackpad.


Should I get a chime with no ssd installed?

 

[dukefawks]

SMC_LID? Trackpad connector corroded?

 

[gcain]

SMC_LID = 3.41

Trackpad connector looks good. The whole board looks really good except for that one spot around C4020.

 

[gcain]

PP3v3 @ C9009::1 is 2v

It should be 3v right?

 

[dukefawks]

Of course it should be 3.3V. Guess a trace is fucked or 3V S3 FET.

 

[gcain]

R7811::1 == 3v3
R7811::2 == 2v0

So would this imply S3 FET is okay and something is pulling it down on the outside of R7811?

How can I measure a resistor that is rated at 1/10w?

 

[dukefawks]

R7811 is dead of course. Something fried it, so check for short on 3V S3 rail.

 

[gcain]

Removed R7811 and couldn't find a short on the ::2 side.

Replaced with a fresh new R7811 and everything is happy again.

Mark solved please.