Macbook pro A1706 820-00923-A BKLT_EN_R missing

[kingskie]

Hi all,

I need some help.
I received Macbook pro A1706 820-00923-A from customer that was water damage.
After open it there was a liquid damage around lcd connector. I clean it and measure but there is no short.
Tried to turn it on but got blank display but the fan spin and the keyboard backlight is on so i think it only has problem with backlight or display.
So later i measure J8500 port:
PPVOUT_S0_LCDBKLT = 0v
PP3V3_S0SW_LCD = 3,2v
PP5V_S0SW_LCD = 5v

So i measure R8442 near Backlight ic and found out there is no Voltage on BKLT_EN_R.
The BKLT_EN_R goes straight to CPU. does it means that CPU is fail or am i missing something.

So i was looking for the source as you can see in the picture that
LCDBKLT_EN_L is 12.9V
PPVIN_S0SW_LCDBKLT_R is 13V
but i get 0V on PPVIN_S0SW_BKLT

so does it mean that the main problem is Q8400 mosfet?

Really appreciate for the help.
http://www.imagebam.com/image/3b12301330282981

[piernov]

Re: Macbook pro A1706 820-00923-A BKLT_EN_R missing

Take a picture of the LCD connector on the logic board.

[kingskie]

Re: Macbook pro A1706 820-00923-A BKLT_EN_R missing

Take a picture of the LCD connector on the logic board.

here is the picture
http://www.imagebam.com/image/97a8851330707138


http://www.imagebam.com/image/6bccf01330707700

[piernov]

Re: Macbook pro A1706 820-00923-A BKLT_EN_R missing

It doesn't look like the connector itself is liquid damaged so that's a good sign.
I think you have image but just no backlight. Measure resistance to ground on PPVIN_S0SW_BKLT, with sceen connected then screen disconnected.

[kingskie]

Re: Macbook pro A1706 820-00923-A BKLT_EN_R missing

It doesn't look like the connector itself is liquid damaged so that's a good sign.
I think you have image but just no backlight. Measure resistance to ground on PPVIN_S0SW_BKLT, with sceen connected then screen disconnected.

i get 0.736 with and without LCD

[pgoodpgood]

Re: Macbook pro A1706 820-00923-A BKLT_EN_R missing

You can shine a bright torch through the apple logo. If backlight is problem you should see a portion of your image on the screen.
You will then know if it is no-backlight with image or no backlight with no image. Then you know where to troubleshoot further.

[kingskie]

Re: Macbook pro A1706 820-00923-A BKLT_EN_R missing

Thanks for the reply.
I already tried with torch but there’s no image at all so i think it is no image and no backlight.
Any suggestion for the next step i should do?

[Pedro147]

Re: Macbook pro A1706 820-00923-A BKLT_EN_R missing

Hi @Kingskie I have the same board with a similar issue. Did you ever make any headway with this board please ? Not sure if these are Retina screens but they are dark and it’s very hard to see if you have image but no BKLT by shining a torch through the Apple logo

[Jilly]

Re: Macbook pro A1706 820-00923-A BKLT_EN_R missing

the torch through the apple logo will not work on this model, the apple logo is not semi transparent on any with the silver coloured logo, only those with the white logo.

[vinse]

Re: Macbook pro A1706 820-00923-A BKLT_EN_R missing

jump r8590 ,r8591,r8592
check if you get PP3V3_S0SW_LCD,PP5V_S0SW_LCD

[Agrim]

Re: Macbook pro A1706 820-00923-A BKLT_EN_R missing

I have same issue like have trackpad working, fan after a while get turning on but amp meter shows 20.2v and 71ma steady on monitor connected. but no display. l7410, l7420, and l74 30 shows ov . any further help would be appreciable

[mon2]

Re: Macbook pro A1706 820-00923-A BKLT_EN_R missing

What is the voltage to ground of ppbus_g3h ?

You can measure at fuse F7000.

[vinse]

Re: Macbook pro A1706 820-00923-A BKLT_EN_R missing

can you diode mode the edp lines aux P and aux N ??