MBA: Fan spin, chime, backlight no image

jpadie

New member
Not yet tried another screen. But there is backlight.
No question mark folder. Will try an external monitor in the morning though .
 

jpadie

New member
Should add that I bought this one on eBay as the seller said it had been "diagnosed" by Apple as a dead logic board.
 

JohnB8812

New member
It could be a board problem, but best to try another screen first. If no success, then could be a BIOS issue
 

jpadie

New member
Thanks John
i have a compatible display but it's on my daily driver and I'm in meetings much of the next while. So it may be a fortnight or so before I can spare it more's the pity .
 

2informaticos

Administrator
Staff member
Do you get black, or white screen?
If no result testing known good (and compatible) screen, then come back with board model.
Then we see what to check...
 

jpadie

New member
White screen. Chimes and posts. Doesn't boot from external drive or internal ssd. It's an A1369 mid 2011. I will pull the board later today but as per above I won't be able to test with a screen assembly for quite a while.
 

jpadie

New member
it's an 820-3023A board. I don't have boardview and schematics for that yet so another reason for debugging to be delayed.

no orange light on charger but the fan spins, the device chimes and the CPU and PCH get warm as usual. 25v or so near the LCD. seemingly a little low voltage on some of the coils near the CPU (around 0.5v). When I get the schematics I will test some more and post back.
 

2informaticos

Administrator
Staff member
As this is display port, backlight with white screen should be display problem; TFT matrix is not powered.
Be sure is pure white, not the classic "dirty" white, which means image present; don't you get question mark folder?
 

jpadie

New member
on balance I would say it is more 'grey' than white. but the grey of a diffused backlight?

photo here:
 

2informaticos

Administrator
Staff member
If is grey means TFT matrix is active.
Tested external video?
Did you try new BIOS with clean ME?
Also try to start from USB pendrive.
 

jpadie

New member
No luck with external video (thunderbolt)
no boot from external drive (external SSD)
No keyboard light on the shift lock. and kb backlight not illuminated

I haven't done a new bios on this type of logic board. Is it swapping the flash chip out or do I re-flash this chip? In which case what is the process for that (on other devices, such as car flashroms, I tend to use an arduino to write via SPI but there is a probably a better/easier method for macbooks)!
 
Top