1. will probably be the hardest, depending on weather by reducing the footprint you mean making the original iMac case smaller or putting it in a smaller case
2. shouldn't be too hard, you can just use a atx or micro atx psu with few modifications (which is what i did).
3. depending on the case you use this could be easy or hard, a slot loading drive will be harder to find
1. By "reducing the footprint" I mean disposing of the bulky iMac case and putting it in something smaller (but I don't have an Xbox 360 case handy, nor a "pizza box" LC case.
2. I'd have to check read-outs for exactly how much juice the iMac needs. Because I live in the US, mine will differ slightly from yours.
3. The old iMac was slot loading, but I could use tray loading for the new mod.
Ok, for a small case i would look into a mini itx case (some will be a little too small tho), xbox 360 cases are easy to come by, but are actually a little small (especially if you want a ODD)
As for the psu, internally it should be almost identical to mine (if not completely identical), the output from the psu to the iMac logic board will be the same as mine, it's pretty well documented on the net (and pretty easy to run of any atx compatible psu) the only real hard bit is soft power on (i didn't bother with it)
I don't know how "Xbox 360 cases are easy to come by" is for you, but I can't turn up anything. I did find this though (http://www.radiomods.co.nz/imactoatxconversion/) so maybe I could recover a PC case from the university somehow, which shouldn't be too hard.
yeah, a pc case will be perfect, the only thing to note is that the power connector pinnout is for the trayloader, not your slotloader
I'll have to get a new drive anyway...the slot loader mechanism is broken
I'm trying to pull out the bottom housing with flip foot...I've unscrewed everything but it gets stuck at the end (where the CD/speakers/etc. are) because of those little tabs. What do I do without breaking them?
never mind, I got it
I don't know...I neither have a case or power supply ready at the moment. Should I get those before doing the disassembly, or would a cardboard box do okay in the interim?
a cardboard box should be fine (i had a pc in components sitting on my shelf unprotected for a year and nothing ever happened to it)
I managed to unscrew most of the components and got down to the motherboard. Thing's huge (it looks like its shaped like a U). Does it even FIT inside an Xbox 360?
yes, it dose, at least the tray loaders one dose
Actually, turns out that what I thought was the motherboard is actually two components (one of which is the motherboard), but I don't know if they'll reconnect in a different configuration.
ahh, ok, one of those is the psu, you can swap it for a atx one or you might be able to use that board again
My iMac, as it stands today.
The disassembly guide says I should disconnect this (hard drive power source), but it won't budge.
Still no go.
This plastic thing of which I am pointing to connects the hard drive to the power source. It looks like it should lift up from the motherboard end, and probably a screwdriver could pry it up, but I don't want to ruin it.
for the hard drive power connector you either need to grab it with a pair of pliers and pull it out, or get a small fathead screwdriver and pries it out, it can be a pain it it will come out in the end
as for the powerboard connector you should just be able to push the end of that tab closest to the powerboard down and then pull the two boards apart
I think I have to remove all the cables from the hard drive and DVD first. I got the hard drive power connector out, but not any others from the hard drive or DVD cables. I also removed the RAM.
Man I hope this works when I put this back together. 
I think I may be able to pull out the power supply from the motherboard, but I still need to disconnect the optical drive and hard drive entirely, as it's not coming apart very easily, and I think there's still some stuff holding it down. Besides from the hard drive power supply, how do I remove the other cables?
well, the hdd/odd power connectors can be very hard to remove for the first time, they can take some force to pull out. as for any other cables, i assume they just pull out, but i don't have too much experience with the inside of slotloaders ( i only ever removed the hdd from mine to install vnc to update the firmware after i screwed it up trying to install osx without updating first)
The lower cable (connects the CD drive to the computer, hard disk cable disconnected) is difficult to reach and difficult to unplug.
I also want to take out the speakers. The official documentation says I should "roll" the speakers (they're little balls) out from the computer, but they seem stuck and I don't want to break them. What do I do?
Today, I removed the hard drive, though.
Turns out the CD/DVD connector isn't unpluggable, it's a circuit board with tiny screwdrivers.
The motherboard and the power supply have been disconnected! Now it's time to look for an appropriate case...can anyone help?
EDIT: still haven't undone the speakers yet, and I want to save the case.
What sort of size are you looking at? i favor games console / set top box cases in these sort of applications, however you could always look at small micro atx cases (or possibly even mini itx cases)
And to anyone who is interested, i will try to make a guide on how i did this, got annother one to make (and this imac board has one of those scsi cards 
) gonna try to get the cd drive in this one aswell
I want something that will look good next to the TV (or my own monitor, when I finally do decide to get one--an original Xbox case would be swell if anyone has an extra). The idea is turning it into a games console of sorts (general idea--even though it's a computer through and through).
I removed the speakers this morning. There's still the headphones outlets and a tiny black wire that was unplugged (well, it appeared that way--as opposed to torn) that connects to the monitor (going down through another metal mesh thing), meaning that I'm not done yet--although it's entirely possible I can get the computer up and running at this point, without audio/video connections, it's pretty useless.
Not afraid of the monitor when I come to it (goal is trying to get rid of the CRT) as it's been unplugged for at least a year, so no major fear of electrocuting myself (not that destroying the CRT is recommended). More pictures coming soon. 
Orig xbox cases would make a nice case for this pitty i don't have any spare...
On my new one of these i am gonna be using the xbox's power button to turn on / off (and to simulate the xbox's ROL during boot / eject) can supply the circuit diagram if anyone is interested
/still waiting on confirmation of audio/video connections
i don't know about the slotloader audio / video connections
EDIT:Take a look here: http://etech.dyndns.org/index.php?page=vcr.php
seems to have some good info on the pinnouts
Since the iMac has a slot for an extra monitor, couldn't I find some sort of adaptor for that slot and be good to go as far as video concerns?
afik that probably will work, some don't like it but most will work fine like that
Hey, Temporary Joe here again. Tore it down to the CRT system, and I want to the test an external monitor. Problem is, the power supply (plugging in) is all tied up with the CRT. I want to be able to give power to the power supply (a few daisy-chained 9Vs, maybe, but such riskiness means possibly blowing the board entirely).
Any suggestions on how to do this?
OK, i am over the next few weeks gonna be building a rev.2 of this, but with a few notable differences:
1 - This board is slightley slower (233mhz rev A, vs the first which is a 333mhz rev C (guess i could swap the CPU cards...))
2 - I am gonna be using a 2.5" hdd (or possibly a CF card), which should give me just enough space to fit a CD drive
3 - the motherboard will be orientated the right way round (so all the ports are at the back and don't need to be rerouted)
But Best of all, this board has something that afaik is quite rare, a mezzanine slot SCSI card (big thanks to 24bit who gave me this board)
i will take pics of as much of the build process as i can
Ok, some pics of the build process so far...
Cutting the board the DB-15 video plug is on down to fit in the XBOX 360 case:
First i had to remove the port that i belive is used for IR, being too lazy to use a soldering iron decided to use hot air to remove it
270°C for a 60 seconds or so should do it
The Port removed:
Now carefully mark the board and cut off the excess:
Board marked up
My weapon of choice:
And the board after cutting
Now to make space for the ports (i decided to mount them to the side to make cable routing much easier):
Space cut out to mount the ports:
The panel for the ports mounted:
Now to mount the logic board
Board bolted in:
And the ports lined up (well almost, there not perfect but close enough)
And thats where i'm at right now, gonna be working on it over the next week or so, still need to get a HDD for it...
Nice to see your work going on with the oldies. The SCSI HBA was not that uncommon in Germany, I had two with Rev.A boards.
You will know that Rev. A boards also had the Mac floppy pinouts - the connector was missing though. There wont be room for a floppy anyway I guess, but it would be a cool retro hack, SCSI and floppy. I think there was a firmware issue concerning the floppy driver too.
Interesting, as far as i know those boards where fairly uncommon (though not entirely unheard of) in the UK
Also very interesting they had floppy ports, i could proabley just squeeze a floppy drive into it, gonna have to do a bit of googling on that one, would be cool if i could get that to work
EDIT: just looked at it, aparentley it did work, but a firmware update broke it. So the question is dose anyone know which and has anyone ever tried to downgrade the firmware?
A little more, been working on the powersupply today.
Unlike last time i decided not to use a laptop power brick (since i destroyed the brick i used last time)
Wondering what to use i had a bit of a brainwave, the xbox power bricks supply pleanty of power, and i had one that didn't work with any of my xbox's, the brick is 150W so is pleanty powerfull enough.
So, here is the brick, it's a 150W one supplying 12.1A at 12v, originally for use with a jasper revision xbox.
And the socket for it, removed from a dead xbox board:
The wires from the DC-DC board, with pleanty of insulation removed:
Soldered to the socket (allong with the two wires to allow me to switch the brick on):
And the hole setup:
Green lights on both the brick and DC - DC boars shows it works
Might have some more pics later tonight, gonna be getting the power setup installed later today
Maybe someone over at 68kmla has some info about the floppy iMacs. Some hacks were done back in the days, but I did not care much, as I had my Macs with floppy from that time networked together with the iMac.
Note the Microtek on the left hand side. The Canon 2700F is still running with a W98 box.
Not much heating needed in the room, if everything was powered on.
My biggest drives were two 320GB 5¼ SCSI beasts in the metal case below the Epson.
Back to topic:
I dont think Apple would let anybody downgrade firmware. If there is a way at all, it would have to be a third party flashing thingie.
There must be a 10GB IDE 3,5 kicking around, shall I look for it? Maybe too clumsy.
Wow, that is a nice setup
I have been asking over at 68kmla, and it seems someone there wrote a program to flash the firmware on a powermac g3, which may work on the imac if only i could find the firmware for it somewhare.
I do have the hdd you sent me with that board (which is a 10gb IDE hdd) but the problem is firmware based rather than os based
Is there a problem with the 10gig drives? They used to work for me.
Could you figure out which was the last firmware revision working with floppy?
I should have some old firmware upgrades, but of course not the factory release.
Seems I have Firmware Upgrade 1.0.4 from 1998 in storage, but the question is...
Edit: Seems it was the OS rather than the firmware. MacOS 8.5 or lower should have been working with the good old Sony drives from Centris/Quadra. Some newer drives seemed to be unsupported.
well, i have been doing a bit of figuring
there is a article in macworld feb 1999 on this hack, so we know it was working at this time, the last firmware revision (1.2) has a build timestamp of 23/04/99, and it dosen't work then.
so presumabley firmware update 1.2 broke it
so, firmware upgrade 1.0.4 should be just the ticket, just a matter of trying to get it flashed to the computer, which there are four possible ways i can think of to do.
1) modify the updater to not cheack the firmware revision before updateing
2)somehow trick the 1.2 updater into flashing the 1.0.4 firmware
3)flash it with a third party program
4)pull the flash chip off the cpu card and program it in a external programmer
if you send me the updater i will see if i can find a way to get it flashed to the computer
well, seems it works, and the odd thing, seems it didn't need a firmware downgrade.
I did try downgradeing (using a modified firmware updater, thanks to the guys at 68kmla, but i always got prompted that it failed, and the firmware build number, date and time remained the same)
booted in 8.1 and it works, boot into 9.2.2 and it dosen't. gonna try in 8.6 later....
8.1 should be perfect for a retro hack. I think it was the OS that came with the Bondi blues.
You will need the Formac drivers for the SCSI HBA. http://macintoshgarden.org/apps/formac-9902
If needed, I´ll upload the Formac CD to your server.
yeah, i'm quite happy with 8.1 on the box, it is the orig software for the imac, just gonna se which os breaks the floppy drive, 8.5 is fine, so i reckon 8.6 or 9.0 will break it.
And the scsi hba needs drivers? seems to be working fine on 8.1 and 8.5 without drivers
Maybe I mixed up something. If it works, don´t touch it.
I thought Formac had some own flavor of SCSI manager and formatting utilities, probably obsolete if everything is fine with Apple´s SCSI manager.
i must say, i haven't tried formatting and drives through it or anything, just been using it to use my old apple scsi cd drive
And a little update on the os front, 8.6 broke it, on the advice of the guys over at 68kmla i tried differen't Mac OS ROM versions, 1.1.5 got it working
So i am now very happy, the box will have a floppy drive, SCSI and run OS 8.6
Great! I was using 8.6 for many years. Looking forward to your pics of the finished thing.
Can't wait to see more, nice work. Fwiw I would love to get my hands on a scsi card for an original iMac.
Been looking around for a couple of hdd's for this (yes, i want at least 2 in the box, might even squeeze 4 in)
Was originally thinking of using a CF card, but a 16GB card will still set you back £16 a piece (+ ~£2 each for the adapters)
Then i found i can get 20GB 1.8" hdd's for £12 (+ ~£2 each for the adapters) athough they are only slightly cheaper than the CF cards every penny counts with this project
I was gonna use the cheaper 2.5" hdd's, but it is already getting tight for space, had to forfit the CD drive for the FDD
Gonna have some more pics thursday or friday, gotta mount up the FDD
Ok, a little more progress...
Powersupply board mounted up:
Socket mounted (from back of socket):
socket mounted (from front of socket):
Overview of progress so far:
And here is one of the 1.8" hdd's, pulled from a dead iPod 2G, only 10GB tho, getting a second 30GB one:
The FDD drive is cutting it close space wise, forfitting the CD drive for it, but it should just fit, with just enough space to get the disc in.
gonna have to make a custom made cable for the FDD, since no one seems to sell them in the uk
heya! very nice works going on here... ! what about a step-by-step instruction for dummies for these iMac G3 mods? - i've here just a iMac biondi which needs some mods to survive. thx.
I have been intending to do a step by step of this for a couple of years, will do one at some point
Need to get the current iteration of this working first though... think my logicboard died (it no longer seems to give video...)
also think i'm gonna have to use a powerbook FDD drive if i can find the pinout since a desktop one is a tad too high
On another thought, what would people think of seeing a LC powered xbox? I have a spare LC logicboard lying around that could use a use
