Late 2006 iMac will not power on with LCD plugged in

Bobdude161 said:

Hey guys long time, no post. I've got a difficult and quite specific problem with an iMac that I purchased recently. I'm hoping that someone could give me hand.

Here's the issue:

iMac will not power on when LCD connector is plugged into the motherboard. Both Trickle and Logic Board diagnotic LEDs are on but LCD diagnostic LED never turns on.

Here were my troubleshooting steps:
- Removed LCD entirely and iMac booted up just fine
- External/secondary video works when LCD is unplugged
- If just LCD inverter cable is plugged in to the logic board, the iMac boots up just fine.
- But if I plug in the 32ish pin LCD connector, the iMac won't boot up.
- I've tried to plug in two other LCD's from different iMac models (G5/Core Solo), but the iMac will not power on.
- When I say "won't power on", I see the left most diagnostic LED on the logic board light up but that's all. When the power button is pressed, one of the fans moves for a split second but that is the only activity I see.

Some plausible causes?

- Power supply is not 100%?
- GFX chip issue? (but external video works)
- Logic board issue?

Any help would be appreciated. I've scoured the Googles for answers and there are many answers out there but most are generic answers to under-troubleshooted issues.

So I call on you, MacRumors, for help in hopes that someone has come across this or has seen a solution to this issue.

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Bobdude161 said:

That's what it was! The other screens I had were from other models. I happened to have a broken Early 2006 model and used it's screen with the late-2006 iMac and it worked. Thanks jpcoelho!

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