MacBook Pro 15 2014 no backlight working and no battery detected


This Mac was bought from the previous seller with a defect on the battery which turns off when charger is disconnected.

I tried the new battery before changing it but the problem still was there, even making a SMC and PRAM reset.

Following a couple of threads, there were suggestions that could be a SMC issue caused by water, so I disassembled the mainboard to check it.

There was not any sign of water damage or visual issue on the SMC. The only issue that I saw was a little green rust on the J7000 magsafe welds. I cleaned it with alcohol and assembled again. The Macbook started normally and the battery still was not present.

After checking more threads about this, I opened it again in order to make a deeper investigation on any burnt IC. I have not seen any damage or any component which could be burnt. However, when I assembled it again the backlight on screen was not working.

Checking this two threads, I started to test all the components involved following the schematics for 820-3787-A board.

Lcd no back light

No backlight, fuse blown? Works fine except backlight! A1398

First that I checked was the fuse, which was OK. So I plugged the board and checked the voltage, which was 12.6V (ok)

Next, I tested the boost capacitors trying to find 55V but there was not. Following the fuse voltage I found that on the pin 4 of Q7706 (marked on red on the picture) there was 12.6V but some mV on the output.

Could be this IC the problem or maybe am I missing anything?

Block Image

Block Image

Block Image

The blue marked capacitors have different colour then the other ones

Thanks in advance for your help

Contesta esta pregunta Yo también tengo este problema

Es esta una buena pregunta?

Puntuación 0
Agregar un comentario