820-3437 no display

[arnonabuurs]

Hello, I have this 13 inch Air with no display. Backlight turns on 25v and also have 3.3v going into the display connector. Tested with another working display and same, i can see it turn on but no apple logo appearing. What to check?

Resistors on SMBUS, LED Return and DPI Int are measuring OK

 

[JohnB8812]

This could be a corrupted BIOS. Try another BIOS for testing, but save the old one!!

 

[arnonabuurs]

I tried another BIOS but the same, also did a pram reset for good measure but that didnt seem to work at all, no flash in the display. So the mac spins 3x, then the display turns on but stays black. Option key also did not respond. After a minute or so fan starts to spin high (not that I only have the IO board, external USB keyboard, fan, SSD and display connected). I put the old ROM back, same issue.

PS I did notice the ROM is different. This is a 820-3437-B and I have many of those lying around but all of them have a ROM that looks like the one in the image on the right side, the left one is the one soldered on the board as you can see:

https://drive.google.com/open?id=1tz4NMVshS2gxrDQ9jnSfxLHe7DygGVnt

Any thoughts on this?

 

[Alan.L]

anything on external display? any light activity on USB Mouse?

 

[arnonabuurs]

Nothing on external display and I do have light on the USB. TIme for the trashcan? It was liquid damaged maybe some dirt got under the CPU.

 

[Alan.L]

you need to unplug the internal lcd cable if you want to use external. thats a good sign if you get light on the usb

 

[arnonabuurs]

Found the issue, the SSD seems to short the board. Weird thing is i tried and external SSD that didnt work. Now i used an known working internal SSD and it works. Thanks so much for the help learned a lot again, this case can be closed!