820-00840 A1708 2017 External display but no video out on built in LCD

Liquid damage on LCD connector but only where it connects to the screen not on the logic board. Tried a replacement screen and also replaced the cable as it was seriously burnt / corroded but no luck.
Only one of the USB C ports works at the moment the other one just keeps blinking the AMP/Volt meter.
I get output to an external screen but no video on the built in LCD ( I think there is backlight but no video)

What should I measure as I am at a loss.
Thanks
 

2informaticos

Administrator
Staff member
Liquid spill on the other LCD connector is equally dangerous.
Check diode mode to ground on EDP_INT_ lines...
 
1 edp_int_aux_n = 0
3 edp_int_aux_p = 0
7 edp_int_ml_n<0> = 0
9 edp_int_ml_p<0> = 0
13 edp_int_ml_n<1> = 0
15 edp_int_ml_p<1> = 0
19 edp_int_ml_n<2> = 0
21 edp_int_ml_p<2> = 0
25 edp_int_ml_n<3> = 0
27 edp_int_ml_p<3> = 0
 

2informaticos

Administrator
Staff member
I'm not sure what you did there.
I said to check diode mode to ground.

Read "How To collection" thread, if you need help.
 
Hi, I did do diode mode to ground. Red probe on ground and black probe on test points. What did I do wrong? Also checked these test points on another working board and got the same results.
 

2informaticos

Administrator
Staff member
0 means zero, SHORT to ground.
If you mean OL, tell us.

OL is what you get, for sure; just saw the series caps now.
You should get something around 0.400-0.700 in diode mode, on the left side of the caps C8520-29.
 
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