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[SOLVED]820-2914 Backlight but no display

ALB-Repairs

ALB-Repairs

Member
Hi, we recieved a 2914 with LVDS damage and so we replaced the LVDS
We now have 33v on backlight output, but the screen remains black.

We have tried another screen assembly, same results.
We have 3v3 at L9000 as we should, and U9000 is functioning normally.
L9010 and L9011 have been replaced with no difference.
Ive also tried a new Bios just encase (as i have seen this due to bad efi before)

Starting to think maybe gmux? :/
 
D

dukefawks

Administrator
Uhh you say backlight and no image but with 1.6V on PWM I doubt there is even backlight. So what is the issue, no BKL or no image?
 
ALB-Repairs

ALB-Repairs

Member
Duke it has 33v on backlight output (at the LVDS) i ran PRAM resets, and it went up to 35V.
The screen remains black with the backlight present. As far as i can see its probably a fried GMUX. The machine came in with physical damage to the LVDS. all we did was replace the LVDS, should be a simple repair.
 
ALB-Repairs

ALB-Repairs

Member
How should i check them?
i havent checked the traces for continuity to the gmux.
I have checked all GMUX related resistors though.
 
ALB-Repairs

ALB-Repairs

Member
OL on LVDS_CONN_B_CLK_F_N takes me right back to thinking its the gmux. Compared against another 2914 board and got different results. Will change the gmux and report back.
 
ALB-Repairs

ALB-Repairs

Member
dukefawks said:
Why not give me the readings to make sure. Swapping a GMUX is a pretty shitty job.
Click to expand...

Yeah, i got a misprinted stencil, so im balling them by hand takes me about 25 minutes start to finish which sucks.
Anyway, Gmux replaced and board is now fully functioning.
Thanks
 
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