I have a busted 800MHz Superdrive 15" iMac G4 I picked up for free recently and can verify what's just been said about the wiring. (Mine is DOA so I suspect the power supply and/or motherboard.)
The crucial connector is the silver coloured one photographed above, which is actually quite small and has 21 pins, clipping into its mate on the motherboard with a satisfying 'click'. There is also the second cable talked about which seems to be for power to the LCD and other devices along the way.
Now I also happen to have the service manual, and have just been Googling for data. Here's some of what I've come up with:
The Geforce 2 graphics card does all the video scaling by itself, supporting fullscreen stretched resolutions at:
640x480 @ 60Hz
800x600 @ 75Hz
1024x768 @ 75Hz
The secondary output is a Mini VGA plug (14 pin) and supports mirror mode only, unless you use a firmware patch.
I don't know much about internal connections to digital displays, but which is more likely: this crucial 21 pin connector is VGA based like the secondary output or is something exotic linked to this specific screen?
As said by Stadsport on the other thread:
I had this idea a while ago, and after doing some research I found that not only does the iMac G4 use a wonky connector for the screen, but I'm pretty sure the LCD has no onboard image processor. The iMac's logic board handles the picture.
Damn! Sounds like it may be a better idea to remove the LCD and replace it with an identical sized (and maybe higher res) new one whose inputs are known.
Anyway, since I've been elbow deep inside my broken iMac several times I'd like to add the following notes:
- The iMac uses a full size parallel ATA hard drive and optical drive, which are master and slave on its single IDE channel.
- The hard drive and power supply share space right at the top of the dome, closest to the neck.
- Fitting a Mac Mini inside is quite possible on first glance, but NO WAY with a full size optical drive at the same time, however a 3.5" hard drive is probably fine.
- Inside the iMac case is a metal structure called the Faraday Cage which basically makes for a thicker shell, reducing the space from what you'd think
- The drive slot at the front is very easily made to open, so you don't need a perfect match to make it work, however a slot drive would need to be "helped" whenever you want to open the door without a disc already in the machine!
- Intel Mac Mini's have a large power supply brick which takes the same plug as the iMac but is too big to fit inside the case as well as a Mini, so an external cord trick would need to be used.
Anyway, keep this project alive as I know there are many Sunflower Mac lovers out there, including latecomers like me, who want Intel power in a design classic case. May the hack be with you!