Chosen Solution
I’m growing pretty frustrated. I didn’t check the unit when I first got it (and should have) to confirm that it ever had video, but proceeded to upgrade the original 500GB hard drive with a new SSHD. I’d done the upgrade on a mid-2010 iMac (core I3) and didn’t find it that tough, so I wasn’t scared off from upgrading the mid-2011 iMac Core I5 2.5QC unit. Unfortunately I’ve since never been able to get video on the internal display. I’ve replaced the inverter board (maybe with the wrong part? though it was listed as for Late 2009 Mid 2010/2011, part number 661-5976). The original was listed as model V267-707 (no other indications on it that made any sense to me as a part/model number). The replacement part was promised as working when it was pulled (and tested). I also replaced the LCD panel, though was a bit stymied with it, and wonder if some of the issues might still lie with the panel. When I got the panel it only had one cable still attached to it. The vertical sync and thermal sensor cable wasn’t attached, nor was the displayport cable. I had ordered a replacement displayport cable as the one that was originally there had been damaged previously (as best I could tell). It literally had pins broken on it. That damage was part of why I wound up buying a replacement LCD panel thinking that display had been damaged. Replacing the panel and the backlight inverter board didn’t fix it, and now neither has replacing the logic board. I just ordered another inverter board that was the same part number/model number that was there previously, again promised as working when pulled. Would a bad v-sync cable cause no video on the internal display? Finally, in my own troubleshooting (thanks to previous questions and answers here), I had seen suggestions to test with external display. The original logic board actually tested out OK with an external display, and the logic board that is in the unit now tested out OK too, at least a few times. I have a flaky 3-in-1 mini-displayport adapter that was plugged in and with it I could get blinking video for a bit on an spare LCD flat panel I’ve used with PC’s in the past (and have also used with a Mac mini). When I switched to a mini-DP to DVI cable to use that monitor it works well enough to show me the Mac boot screen on the external (as it was trying to load up off of DVD media), but upon shutdown and restart, the monitor no longer showed video. Mac boot sound definitely still there, and I can hear the DVD being read when I have it in there to boot from. I have tried resetting the PRAM as well, but getting any output back on the external display or on the internal has been impossible thus far. I’d really like to get this box going, but thus far it seems to be highly resistant to my efforts.
Persistence pays off. I did replace the video sync cable, but also went back and double checked all of the connections on the LCD panel. Then taped things down a little more just to make sure that the connections would stay tight. Also replaced the Inverter board one more time. Put the thing back together and finally got to see the screen light up! Then ran into issues trying to install the OS on a blank drive as the DVD that had the OS on it would boot, but never completely load and wouldn’t take me to a menu where I could choose to use Disk Utility to wipe the drive and install the OS on it. Installing from USB media worked, though it took a while in the installation phase and stuck on an estimated 1 second left before rebooting (that was more like 25 minutes).
