[SOLVED]820-2915 works on external (more GPU woes)

[ALB-Repairs]

Not that interested in weather or not this actually gets fixed.
But i have a 2915 here that i fitted a GPU to (6750M)

The original symtom was no display internal and hangs on boots (external)

Ive got it all running on external, but the internal doesnt get recognised. LVDS looks clean, checked with a known good assembley, LCD_PWR_EN is not present, But 3v3_S0 does get to the screen.
Im only getting a bit wound up by this as its running stress tests perfectly and responding completely normally other than the lack of display on internal.
Is there anything to check?
Its worth noting that u9500 had been replaced prior to me getting the machine. Im hoping its not the gmux or a PCB issue

 

[dukefawks]

Uhm, tried a known good LCD/LCD cable. Inspected connector for damage?

 

[ALB-Repairs]

Yes, Ive used a known good screen assembly. The LVDS connector looks undamaged with no corrosion, ive also inspected the inside of the connector for burns. Everything is clean, so im doubtful its the LVDS connector

 

[dukefawks]

Follow LVDS_DDC and LVDS_EG_DDC. These data lines will recognize the LCD. Check diode measurement too.

 

[ALB-Repairs]

It was the LVDS despite it looking perfect inside and out.
New LVDS connector solved the problem.