820-00165 no greenlight in S0 state

[speggio91]

For lcd backlight controller you mean LP8550 (U7701)?

In the schematics I've found only BKL_SDA and BKL_SCL. Did I miss something else?

BKL_SDA = 0.554V (diode mode)
BKL_SCL = 0.553V (diode mode) and 3.3V (voltage to ground)

I've also tried to run the ASD in another good known board and that error still show up.

One thing I noticed on the water damaged board, is that on the half bottom right side of the LCD, there's a spotlight effect, that doesn't happen with the good known working board.

[mon2]

Then the asd does not appear to be helping. The smbus lines look ok.

The bad lcd works the same on the good board?

Need to determine if the fault is in the display assembly or the logic board.

[speggio91]

The LCD show spotlights only with the bad board. With the known good one there's nothing visible.

[mon2]

On the LP8550 backlight controller are OUT1..OUT6 lines to drive the panel matrix of leds inside the lcd display. These pins will reach the lcd connector on the logic board.

remove all power. Meter in diode mode. Goto the good board and have the lcd connected. Again, no adapter and no battery.

red meter probe, yes red to ground.
black meter probe to pin #1 on the lcd connector on the logic board.

what is the diode mode measurement?
repeat for each pin on the lcd display connector.

repeat these measurements on the bad logic board.

post all measurements.

[speggio91]

good board display connector diodes measurements (display attached):

1. 0.0V
2. OL
3. 0.62V
4. 0.62V
5. OL
6. 0.66V
7. 0.66V
8. 0.66V
9. 0.66V
10. 0.66V
11. 0.66V
12. OL
13. 0.0V
14. 0.63V
15. 0.58V
16. 0.58V
17. 0.0V
18. 0.50V
19. 0.50V
20. 0.0V
21. OL
22. OL
23. 0.0V
24. OL
25. OL
26. 0.0V
27. OL
28. OL
29. 0.0V
30. 0.0V

bad board display connector diodes measurements (display attached):

1. 0.0V
2. OL
3. 0.63V
4. 0.63V
5. OL
6. 0.66V
7. 0.66V
8. 0.66V
9. 0.66V
10. 0.66V
11. 0.66V
12. OL
13. 0.0V
14. 0.63V
15. 0.58V
16. 0.58V
17. 0.0V
18. 0.50V
19. 0.50V
20. 0.0V
21. OL
22. OL
23. 0.0V
24. OL
25. OL
26. 0.0V
27. OL
28. OL
29. 0.0V
30. 0.0V

Might be that LP8550 is defective? Does this have anything to do with the sensor failure?

[mon2]

No difference.

see your post #5 in this thread. Review the bad board lcd connector pic and focus on the smd soldered pins. You can see solder shorts near the plastic of the same connector. This connector must have been replaced. Flux the shorts and use solder braid to draw up the shorting solder bridges. The good board is clear between the lcd connector pins.

[speggio91]

Finally I think I've fixed it!

What did I do:
-Retouched with flux and solder all the connectors of J8300
-Replaced U5810
-Replaced U3540 (not really necessary but it didn't have a good look)
-Retouched pins #11 and #12 of U5800 which was previously reflowed but those two pins seemed to not have a proper connection with the board.

What a journey! Thanks you all for the support and I hope this topic will help someone else in a similar situation.

Merry Christmas!