820-01958 PP5V_MAIN_ALSCAM_F short "burnt coil" (using 820-01521 board view)

[KC Micro Tronix]

I have seen this a few times but never really fixed it.
The PP5V_MAIN_ALSCAM_F fail was dead at J8550. A burnt inductor was obvious on the LB.

Repaired the damaged traces and was able to return power to PP5V_MAIN_ALSCAM_F at J8550 but still no display.

These machines come in for damaged displays and when they replace the screens and they still don't work I end up with them. I was wondering if anyone has figured out what else gets damaged when this goes. There is a similar fault on the 820-01521 and my repairs have met a similar fate. All the rails on J8550 are present and the machine does boot just no image.

 

[2informaticos]

Do you mean J8500?

L8570 usually fails because of short in the video flex, inside LCD panel.
Liquid spill inside of video connectors can also generate such issue.
The big problem is that some camera data lines go to T2, there is not a separate camera chip (like in previous models).
U8595 doesn't completely separate camera and T2.

I think T2 maintains a relation between camera, LCD connector and eDP output.
Check diode mode to ground on data lines of camera and eDP.
Also try changing U8595.

 

[KC Micro Tronix]

so U8570 can cause no image on the screen? or just problems with the camera?

 

[2informaticos]

I cannot find U8570 on 001521 schematic.

 

[KC Micro Tronix]

sorry U8595
The one you were talking about.

 

[2informaticos]

If you are sure the short inside display assembly didn't affect video lines, try changing U8595.

Do you get external video?