Updates:
In a flurry of activity I have now re-wired the power button and LED, replaced the front audio jacks with HD Audio versions, ripped an amplifier from some power speakers and adapted it to power the iMAc speakers, re-bodied a modern slot loading DVD drive into the old DVD ROM drive case and installed the PSU.
Here are a few pic.s of the progress.
Power Button and LED
This is the original wiring:
Basically four wires, black, white, red and green.
From the front it looks like this:
A bit of simple checking with the multimeter shows the wiring: Black is power switch return and LED return (i.e. they both use this wire as their negative lead like with the G5 powermac and others); white is power switch positive side; red is "LED 1" positive and green is "LED 2" positive.
Here, note the LED is a bi-colour LED, one green LED and one amber LED. It turns out that LED1 is the amber and LED 2 is the green one.
For a standard power on LED you should only wire up one of these and then insulate the other wire.
As you can see I kept the connector and then spliced on motherboard connectors and insulated them - job done!
Front Audio Jacks
These are the wire colours on the original audio jacks
and this is the original board:
I probably should have taken my time and checked the wires of these and seen if I could re-wire them to meet the HD Audio standard for PCs, but instead I took the faster route and found that the good old Corsair Obsidian has a pair of audio jacks on the front panel connector that have the same spacing as the iMac.
So I decided to use this (also the power switch, LED, USB and USB 3 connections from this Corsair panel I am re-using in the build too) .
So it was a simple case of remove the original board, cut the audio connection part from the Corsair board (luckily all connections are exactly behind the jacks), and hot glue the new trimmed board in place for a perfect fit.
IMac Speakers
I love the original speakers, but they need an amplifier and so out from my pile of stuff came a pair of old Phillips mains powered PC speakers.
A couple of minutes with a multi tool later:
Good news - they work from 12v…this fuzzy photo shows a mains to 12 v transformer:
So here is the board and transformer combination:
A close up of the PCB:
The large capacitor on the right is a smoothing capacitor - to smooth out the converted 12 volt AC and at the bottom, the four diodes are a simple bridge rectifier design. These components are redundant for me as I will be using the 12v regulated from an ATX supply.
So the plan was to remove the capacitor and input DC 12 volts directly across where the capacitor had been, making sure the ground side of the 12 v is connected to where the negative side of the capacitor was (as shown here):
and now with capacitor removed:
After that it was just a case of de-soldering the old speaker connections and wiring in the iMAc speakers and adding a molex power connector.
And here is my amplifier module now mounted in place:
Power Supply placement
I had decided to use my Silverstone SFF 450W PSU as it is nice and quiet, more than powerful enough for what I want to do and more of a challenge to fit than a PicoPSU (!). Also my pico is for my Cube build, so as I had this supply I decided to use it here.
I wanted to place it low in the case, breathing from the lower half, but of course as the iMac tapers it will not all fit under the large metal floor, so I need to cut the floor to allow it to poke through.
First though I needed to make sure it would be as far to the front of the case as I could get it without it interfering with the drive holder. It needs to be as up front as possible, because the case is fatter there.
Here is my best guess of where it needs to sit having placed the hard drive holder in position:
So I drew around the supply to define a hole for it:
and 12 cutting disks later this is the first fit from the top side:
By top side, I mean the side where the motherboard will be, so the plan is to have wires for the motherboard coming up from the supply and wires for the hard drives, amplifier etc going down to the underside of the support shelf.
The metal plate by the way is the heaviest duty Mac case metal I have so far encountered. It is way thicker and harder to cut than a PowerMac G4 or 5….I needed around 10 disks for this hole.
I then did a check with the faraday cage on to see how the power supply would "sit"
Finally then today I installed all of the parts to see how everything looked:
Pic above shows the "under" view without the faraday cage but showing PSU, amplifier, and all drives and wiring.
So far so good….
Next to come is then taking it all apart again for the side IO panel and also putting some motherboard mounts on the top side.
