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2 Video card or logic board issue
This iMac boots to hard drive and I can connect remotely with screen sharing, I run system profiler and check the Graphics/displays and it shows nothing connected does not show the video card. There is no display, sometimes I get a gray flickering screen and other times I get the black screen, I tried the external output with a dvi to VGA adapter and get no output to the monitor, ( I verified that the ext monitor and adapter operate with my working machine) LED 1 on, LED 2 on, LED 3 on, LED 4 sometimes is on and other times not (???). I reseated the video card and double checked all connections. I am unsure which part has failed on this unit any input is appreciated, and many thanks in advance running OS X 10.6
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I replaced the LCD cable as a precaution (the old one looked shorted) with no result I will try replacing the inverter as the next step, but the no video output to the dvi leaves me suspicious of the video card I will check back in with results, thanks
von junvaz
I just wanted to give an update so that this information can help someone with the same symptoms, scince I was able to use the share screen feature to verify the main board and Hard drive were operating and found that the system profiler was telling me that no video card was present, I obtained a replacement video card and the problem was solved. The machine is now in working order, I ran tech tools to verify all hardware and passed with flying colors. I am guessing that whatever component has failed on the old video card was fooling the logic board into allowing LED 3 to light up and LED 4 to light intermittently.
Problem solved with New video board.
Thanks to everyone and hope this helps someone else.
von junvaz
+ Very well done !
von mayer