820-3023 fan o.k, chime o.k usb o.k...white screen

[yair37]

hi, i have old board that i want to renew, i have full working body for it...there was very small liqde damage near lcd connector i was renew pins(2,3 PPVOUT_SW_LCDBKLT) still the same, i was sew also near u3890..clean and look o.k...any idea?
THANKS!

 

[2informaticos]

Pure white screen means TFT matrix is not powered up.
Usually 3.3V doesn't arrive there.
Check another LCD assembly...

 

[yair37]

Lcd os fine..check it with different good board

 

[2informaticos]

Then change LCD connector, J9000.

 

[yair37]

change...the same..

 

[2informaticos]

Do you have all voltages correct on the connector?

 

[yair37]

changed u9000 not help..stiil white screen

 

[yair37]

PPVOUT_SW_LCDBKLT - 26.7v
LED_RETURN_6 - 0.7v
DP_INT_HPD_CONN - 2.7v
I2C_TCON_SDA_R - 3.3v
PP3V3_SW_LCD -3.3v
DP_INT_AUX_CH_C_N - 3.0v
DP_INT_ML_F_N/P - 0v

 

[2informaticos]

Check all the caps C9020-25 and R9017/18.

 

[yair37]

looking o.k(compere with other board)

 

[2informaticos]

Then must be CPU internal problem.

Just in case, try few PRAM resets...

 

[yair37]

PRAM not help...so reheat CPU can help? or dead board?

 

[2informaticos]

You can heat for test...