Backlight keeps going out randomly during use.
The backlight randomly goes off during use. If I hold a light up to the display, I can still see the picture. The fans are not running higher than normal and from what I can tell, the temperatures are not unusual (see screenshot below). The LCD proximity temperature has reached 105 degrees, but it shuts off at any temperature below that as well. I have checked the energy, backlight, and screensaver settings. I've even disabled sleep and the screensaver just to help troubleshoot. I've reset the SMC and PRAM multiple times. There are no diagnostic LED's that I can find on this model of iMac, so that doesn't help. The 3 things that I tend to suspect are the Backlight Board, the display itself, and the Power Board. I consider my most likely suspect the Backlight Board, but I'm just struggling to be convinced of any of them.
I have researched and read a number of answers/articles on iFixit and elsewhere trying to find a solution to this problem. I'm trying to narrow down the culprit without spending a ton of money on parts that may or may not be bad. From what I've read, no one has really found a true solution. One "workaround" was to lower the brightness, but this is for a client and I want to fix it rather than simply provide a workaround that doesn't truly resolve the issue.
The reason I'm asking a question is because I'm having a hard time figuring out exactly which part is most likely defective. The Backlight Board would be the least expensive fix, but I've read multiple times where that doesn't resolve the issue. I've also read about people replacing the LCD and it not resolving the issue either. I thought I would put it out there and see if some more experienced people might have some thoughts about which device is most likely the issue. If at all possible, I'd like to avoid buying one part, testing it, finding out it's not the issue, then moving on to the next one.
Any thoughts and suggestions are welcome. Thank you!
BTW, this iFixit Q&A most closely reflects my issue and it did not resolve my issue: http://goo.gl/CfeM8I
Is this a good question?