G4 Power Supply Mod

Posted by: macwarrior

G4 Power Supply Mod - 12/29/05 04:13 PM

I have a gutted Power Mac G4 (PCI Graphics) with just the power supply. I want to mod it and turn it into a Firewire Enclosure. I already have a 4 drive 800/400 Firewire Bridgeboard from Cool Gear and 4 hard drives to install. I have done alot of searches and can't find anything anywhere on how to mod the power supply as a switchable supply without having it connected to a motherboard. I don't mind taking that power supply out and putting in something else but I haven't found a "firewire power supply" to put in its place.

I am open to just about anything, short of buying a 4 drive firewire enclosure. Any help would be greatly appreciated.

Posted by: Waragainstsleep

Re:G4 Power Supply Mod - 12/29/05 08:08 PM

It strikes me as the sort of thing which is easy if you know about these things. So you need to find someone who knows about these things. I would ask Tycho. He knows all about these things. Don't expect a quick reply though, he's a busy man these days.


If it helps, the G4 PCI Graphics (aka Yikes) uses the same board (and hence PSU) as the B&W G3. Maybe that info will help you find a previous example of someone doing something similar. Your PSU is actually very similar to a stock ATX PSU. It has an extra 5V line (think its -5V, not sure). Its usually white.


You can easily convert it to ATX by snipping the white 5V wire. This means if you can find a faulty logic board from a G4 PCI, G3 B&W, or any ATX PC (or Beige G3 they are ATX too), then you might be able to use it switch the PSU on. Its not an elegant solution, and you'll need a CPU too I guess, but it should work. Perhaps you can find a cheap board with a broken port or RAM slot.
Posted by: macDeviant

Re:G4 Power Supply Mod - 12/29/05 08:52 PM

i was going to do something similar of my own. i was going an ATX PSU and put a switch on the purple wire to ground. it should work and an ATX PSU will give you a lot more flexibility on wattage output. also you wouldn't need to hook up any sort of anything inside besides what you need.

hope this helps. here is the thread to my post about this. PSU question for ext. FW enclosure

by the way i like the idea of using a g4 case. i was thinking of using a g4 Cube's case at one point. maybe i'll put my Biege G3 tower to work as a RAID tower. also you might think about doing a LED HDD activity light mod for each of the HDD. here is a good link to use.

good luck

Posted by: maestro

Re:G4 Power Supply Mod - 12/30/05 01:09 AM

You can jump any power supply with a paper clip. When I get a little time I will post the exact how to. It would be super easy to put in a switch to turn it on and off.

Posted by: macwarrior

Re:G4 Power Supply Mod - 12/30/05 03:12 AM

Funny you should mention that about the LED's for each HDD. I was really thinking about doing that when I Mod the case. Thanks for the link.

Posted by: macwarrior

Re:G4 Power Supply Mod - 12/30/05 03:18 AM


I look forward to your post. The sooner the better :woohoo: .