1.83 GHz Core Duo or 1.83, 2, or 2.16 GHz Core 2 Duo A1208 (EMC 2104/2110/2114/2124)

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White Intel iMac won't Start if the LCD is Connected?

hi everybody,

a friend of mine gave me an intel iMac with a strange issue - the iMac wont start if the lcd is connected - there is only a slight movement on the fans and thats it - if i disconnect the lcd - the iMac powers up without any problems.

i changed the lcd and the cables - still the same problem

what do you think about that ?

PSU ?

Answered! View the answer I have this problem too

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hi vince,

no - it wasn't the inverter - it was the lcd - i changed the lcd and everything was fine.

accepting my answer to mark it as resolved

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Most Helpful Answer

Try resetting the SMC. Ralph

http://support.apple.com/kb/HT3964

You might also reset the pram. Ralph

http://support.apple.com/kb/HT1379

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My personal opinion is that there is something wrong with the LCD's inverter. I know if there is a short in any power supply the computer will shut down. The iMac runs on 5 and 3.3v but also has 12v fed through the Logic Board to the inverters. So if you have a shorted inverter it wont start up. You have a problem with the inverter or the video. And a connector for each one so you can unplug the power to the inverter on the logic board but leave the video connector in and if it starts up you have a bad inverter.

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Good news, the inverters are on the side of the LCD panels, did you put the old inverter on the new panel or did the new panel come with a different inverter? Just curious for my own sake.

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since i've had not only one iMac - i took the lcd from a different one. the inverter was not the problem, if the inverter would fail - the iMac still would boot up.

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You changed two things and the computer works, but you can't say with certainty which one was causing the problem. There are a lot of people out there who don't have extra displays with inverters to fix their problem. I'm sure it doesn't matter to you since your computer it running, but I don't understand why you don't think it could be the inverter since they go bad much more often than panels do. If they fail the computer will still start with no light, but if it shorts it won't.

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no, never changed the inverter - never said so.

if the inverter is shorted - you could probably hear/see/smell/feel it. it has nothing to do if someone has more parts as others. and for the panel problem - i had never an iMac with a shorted inverter. but many with some kind of lcd defect (sure, mostly they have connection problems resulting in the vertical lines). so i would firstly not assume a shorted inverter.

i understand your position at all - but i can't compare myself with others - thats true - i have some spare parts here and i do those stuff for more then 10 years

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I just trouble shot whether you can use a G5 lcd in an intel imac. This is what happened..I took the lcd LM171W02 (TL) (B2) off my C2Duo Build 10K459, and put the lcd LM171W02 (TT) (A1) from my isight G5 build 9L319 onto the intel unit AND.. after a short burst of the fans - it would not power on. I pulled the lcd cable from the socket - and the C2D powers up. I return the cable into the socket and the C2D fails to power up. I put the G5 lcd LM171W02 (A4) (M1) from my other isight G5 into the C2D and once again it fails to power up after the short burst of fans. There is a detailed working around this problem here. Do any other LCD panels work with this iMac? It is one likely reason for the imac not booting.

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PJ469 - the LCD panels (intel-G5) are not interchangeable. They use different video signals.

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Hi Vince, That's what I didn't say but the evidence points to that - and that's why my intel imac would not power-up unless I disconnected the G5 displays...and what I suggested was a likely cause for the same behaviour Markus described - a short burst of the fans, then nothing. Exactly what I saw and all parts I interchanged for the 'trouble shoot' were working parts as I was simply trying them from complete G5 and C2D imacs.

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markus weiher will be eternally grateful.
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