iMac 27 (820-2901-A) turn on but no image

[Ciki]

Lcd connector is replaced and now turn on ,chime but no image (backlight is on but fully bright ) PP12V_LCD is 11.88V ,PP3V3_S0_VIDEO is 3.3V ,i try different display ,cable,another bios ,graphic card same sh***T

 

[Ciki]

No Title

 

[dukefawks]

Bad soldering on connector or connector damaged. Check C9040 and friends for continuity to LCD connector.

 

[Ciki]

Solder another lcd connector same ,check all continuity to LCD connector all ok ,what else can cause no image ?

 

[dukefawks]

Was the connector damaged to start with? Diode mode on both sides of C9040 and friends with LCD plugged in if possible.

 

[Ciki]

Man to measure with screen plugged in very tricky ,visually all looking good,yes connector was damaged in first place ,solder new one very clean and all connection looking good ,could be SMC or something else

 

[Ciki]

I found another board 820-2091 but this one PP3V3_S5 is missing on U7700,try to replace but still same ,PP5V_S3 is there 5V

 

[dukefawks]

It must be something in the DP lines. Do diode mode on C9040 and friends on pin 1 which is the MUX side. Then check from pin 2 to the other side of a plugged in LCD cable. If that is all good it could be a MUX issue U9200. Check diode mode on C9240 and friends on both sides and inspect for damage around U9200.
Have you tried if external video is working, if not then it could be something totally different of course.