Logic Board 820-00840-A Missing EDP_BKLT_EN

[mferna14]

Hi dear friends., I am working on a Apple MacBook Pro A1708 , Logic Board 820-00840-A that has no backlight. The logic board powers on fine, but no display. After Checking on the backlight driver chip, I found that the EDP_BKL_EN is missing. And this Power Enable comes from the PCH. So does this means this Logic board cannot be repaired & brought back to life again? The resistance from GRD to the test point of EDP_BKL_EN is around is 0.66M ohms. R8442 (0ohms) is ok. Any suggestion/Tip if any would really appreciate.

[sajidmirza]

Remove Q9908 and U8400 and chk resistance before giving up.Give it a try
Good luck

[PITERPENY]

Is the display known to be good? they have a common problem with the flexible backlight cable

[mferna14]

I have a lot of T resistance boards (LCD logic board) & even slightly broken screen for this model. & I even used a Known good LCD, still the same, no difference, thanks PITERPENY

[PITERPENY]

is there an image? since the backlight will not turn on if there is no image! Have you checked the J8500 lines?EDP_INT_AUX_N and EDP_INT_AUX_P ok?

[mferna14]

I get the image dear... I have a bare bone screen & I use a powerful LED torch to get a backlight. I see the Apple logo & the then folder clearly. & what is this for "EDP_INT_AUX_N and EDP_INT_AUX_P ok?"

[reformatt]

Connect via HDMI to external monitor, check internal display is detected and you can vary brightness up and down. Try a PRAM reset, also check I2C lines are pulled up to 5V.