820-00281 no video

[Kyle93]

Arrived with no liquid damage. Customers claims screen just stopped turning on one day. No internal video but external works fine. Do not have a spare screen to test with. Its never been dropped.

What should be checked first?

 

[2informaticos]

Possibly flexgate issue.
Testing with known good LCD assembly is the best option.

 

[Kyle93]

New screen ordered. Will update after it arrives

 

[Kyle93]

New screen arrived and installed. Now have image on the screen but no backlight

PPVOUT_S0_LCDBKLT 0V 0.50 diode mode

What needs to be checked next?

 

[2informaticos]

Chinese screen?
Did you get image with original screen before, only missing backlight?

 

[Kyle93]

Just checked and yes, there is image on original screen as well only missing backlight.

Should U8400 be changed? F8400 is good

 

[2informaticos]

Should be good to test the screens in other machine.

 

[Kyle93]

What else can we try? We do not have other machine like this

 

[2informaticos]

PPVOUT_S0_LCDBKLT voltage (screen connected)?
Also check diode mode to ground; w/ and w/o LCD connected.

 

[Kyle93]

PPVOUT_S0_LCDBKLT 0V with screen connected

diode mode with screen 0.024

diode mode without screen 0.024

 

[2informaticos]

0.024 is almost short; and result to be on the MLB.
What is the value at L8410?

 

[Kyle93]

0.850 with and without screen

 

[2informaticos]

One of C8460-73 should be bad then.
Are many caps there, remove one by one and test each time if diode mode goes high.

Check first if any looks strange; remove that if is the case.

 

[Kyle93]

Solved. C8472 was shorted. thank you