820-01700 No image on internal LCD

Hello. I got a 820-01700 in that had some minor liquid damage around the LCD connector. The LCD connector on the logic board is clean but the connector on the screen side is damaged. I replaced U9850 and replaced the LCD flex cable with a new one and tested the board with another full assembly that is good, but still nothing on the internal screen. No image or backlight. External image works fine though. I replaced U9850 one more time just in case, and still same issue. DP_INT_HPD is 0v and backlight output is also 0v, so it seems the LCD is not being detected by the board. I have correct voltage on the 3v and 5v rails for the screen. Could I possibly have an issue with U9801?


Staff member
Check continuity for DP_INT_HPD from MLB to the TCON board.
Also check if you get 3V3/5V_S0_SW on TCON side.
Wow yea that was it. It was a bad LCD flex cable that caused this. Even though the cable I used was brand new, it has a broken trace in it for the 3v3 power rail, so the 3.3v was not making it to the TCON board. Replaced the LCD flex again and everything is working fine now. Thanks for the assist.