820-00923-A Internal display not working, Booting , But no chime sound

Working fine with an external monitor, Internal display is not detecting, Tried connecting another internal display but still no back light or image.
History - Coffee spilled
Found corrosion on display connector (Not on logic board but on display board). Cleaned it up , Still no change
 
EDP_INT_AUX_P - 0.216V
EDP_INT_ML_P<0> - 0.239V
EDP_INT_ML_N<0> - 0.239V
EDP_INT_ML_P<1> - 0.239V
EDP_INT_ML_N<1> - 0.239V
EDP_INT_ML_P<2> - 0.239V
EDP_INT_ML_N<2> - 0.239V
EDP_INT_ML_P<3> - 0.239V
EDP_INT_ML_N<3> - 0.239V
PPVOUT_S0_LCDBKLT - 1.120V
PP3V3_S0SW_LCD - 0.553V
PP5V_S0_ALSCAM_F - 0.441V
PP5V_S0SW_LCD - 0.550V

I found the one pin burned on the LCD connector(please find attachment), I don't have the schematic of the display board to figure out the net name.
 

2informaticos

Administrator
Staff member
EDP_INT_AUX_P/N must give almost same reading for diode mode to ground.
If not, CPU's eDP output is burnt; there is no series cap to protect it.
 
It may be a stupid question...
Is there any workaround for this signal? By wiring it from any of the USBC display data signals? Or only solution is to change motherboard?
 
I can see similar signals on display mux page , For example DP_DDI2_ML_C_P<0> .....DP_DDI2_ML_C_N<3> ,DP_DDI2_AUXCH_C_P / N , Will it make sense routing it to internal display? ;)

Another question, Any idea about what activities take place by EDP_INT_AUX_P/N. If it is not dynamically driven we can pull them into a high or low?
Because I can see there is a provision for a pullup and pulldown resisters R8502/3

.
 

2informaticos

Administrator
Staff member
I don't really understand what you want to do.
The eDP bus is bad; you can't get image on internal LCD anymore.

U3610 is dedicated for external DP, through Thunderbolt.
 
I mean , Can we replace the eDp bus with DP_DDI? What I understood DP_DDI is also display signals but not for internal display but for external. They multiplux and give for four USBC connectors. My question is , Can these signals drive internal display?
 
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