Chosen Solution

I have removed the LCD panel to repair the CCFL. While I await delivery of the CCFL is it safe to fire up the system w/o the LCD connected and use the ext display?

Yes, the iMac will behave normally with no display attatched. As long as you have the correct video adapter (Mini-DVI to DVI/VGA) you can use an external display without the internal one.

I have the internal LCD display disconnected inside my Mid-2007 20" iMac (EMC2133). I did this to improve overall graphics performance on my external monitor, and to save power on the unused screen. While some online posts suggest you need to disconnect the inverter, LVDS and display data connectors, I had success simply disconnecting the display data connector – it’s the one just below the panel that has two T6 torx screws holding it down. My Mac booted up just fine, no diagnostic light issues or other complaints at all.

This question is not answered. Can anyone describe a way to run an iMac without the internal display attached at all? Thx!!! Ps. I have read it’s impossible, but not from iFixit.