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I have an iMac 2010, 21,5" which has hardrive problem and replaced it. While connecting its LCD with display connector cable, the cable got damaged at one end. I got new display-port connector cable, but still display is not working. When I connected with external monitor, its working fine. I asked at a local repair store they told me that it was either the LCD panel, or the SATA/Board (Logic board?) which would even be more expensive. I thought its a LCD problem, got LCD from ebay but still the display is not working. I did a SMC/PVRAM Reset, but this did not solve the problem. I used flashlight and cant see anything on the internal screen. My question is whether it’s possible to determine if it is the logic board, cable connection, the Backlight controller or the LCD-Panel. Thanks for your answers,
You should try the diag leds first to see if its the lcd. They are just above the mic connector on the logic board. The #4 led is green if the lcd is making connection with the motherboard. If the #4 led is green, maybe the motherboard defective because you changed the lcd and the lcd cable allready.
I had the same problem. Only external video, LED4 of. In my case, inductor L9000 of the logic board was gone. If you want, have a look at my post After HD changed, fuse (wall) tripped, no internal video, but external Regards.
