[SOLVED]820-2915 GPU related headf*ck. Blue tint when using intel HD gpu

[ALB-Repairs]

I had a 820-2915 that had its gpu done in 2015/16 (216-0809000)
This was done by apple, it quit on me and i fitted a new chip.

It looks fine on the boot screen until the driver loads and then it goes blue,
at first i thought id got a bad chipset sold to me, so i fitted another, and it has the same issue.

Oddly enough if i turn of graphics switching the colour profile goes back to normal. Basically the Intel HD3000 isn't working properly.

I replaced the GMUX suspecting that to be the cause, but nope, it didnt resolve anything. Im starting to think it could be a cold joint under the PCH or something. But its really messing with my head.
Anyone seen this before?

 

[dukefawks]

Measure all termination resistors R9650-56. Compare diode mode readings between the LVDS channels. Only thing left is bad solder on PCH/broken trace after that.

 

[Gurmon]

I've seen this. I took a risk and reflowed the whole board in my reflow oven at a high temp. (dont do this ppl) I was out of options. Board worked !! Its been gone for 7 weeks now.

 

[dukefawks]

You cannot reflow a whole board like that. If it really got to the point of melting the solder the board would have been totally fucked. Also without flux it would be pointless.

 

[ALB-Repairs]

Was R9656, measured 5.3kOhm instead of 100ohm. Thanks duke. Youre a star, i would have been chasing that for a long time.

Im still madly confused as to how it went bad, no liquid on this board.ect. overall pretty happy though!