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Hi, I have a late 2009 iMac (EMC2309) which is having an issue with the LCD, the systems backlight will suddenly cut off (used to work around the issue by sleeping and waking the system then the back light would work for a few second to hours at a time) I have since opened the system and disconnected the V Sync cable and that has reduced the issue greatly (as long as I’m on full brightness) Does anyone know if replacing the backlight inverter will help or is the LCD itself failing?
I’ve often had to replace the LED Driver board which is what powers the backlight LED’s. Here’s the IFIXIT guide you’ll need to follow: iMac Intel 27" EMC 2309 and 2374 LED Driver Board Replacement and here’s the needed part LED Backlight inverter board
Exact same problem on a 27” 2009 iMac. I use the same workaround of keyboard strokes to force the display asleep and then wake with another keystroke. The screen runs OK for very long periods at low light settings and is more prone to failure when set at mid to higher light settings. I replaced the inverter board with a used one but the problem got much worse!! I could hardly keep the display illuminated for a second before it went black at any light settings. Electrolytic capacitors on the inverter board might be the culprit. Caps are notorious for failing with age. I see four large electrolytic caps on my board. Perhaps I should acquire some spares and see if that fixes the problem. Anyone had success fixing this issue?
I bought a new inverter board and a rebuild power unit for my late 2009 21.5 inch. The back light works again, but still has problems. Dont know if the sync cable might be the cause or the last high sierra update. Please help!
