Commodore Amiga 4000 PSU upgrade/repair



Even though I have already replaced the capacitors in my A4000's PSU.. I just didn't trust it! Oh and the cooling fan was just too noisy!

So I thought to myself, bugger it I've got a spare A4000 PSU, I'll convert an ATX PSU and refit it in the it's case. So the first thing I did was find an ATX supply that not only had enough current to supply the A4000, but was smaller then the original case so I knew the PSU PCB will fit the original Amiga PSU case.


BeQuite-A4000PSU-1.jpg

The Be-Quiet SFX-300W Does what it says on the tin.. It's very quiet, and has more amps than the original A4000 PSU.

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The BQ PSU could fit in the A4k case. That's as long as you didn't want to connect the mains to it.

BeQuite-A4000PSU-5.jpg

Doesn't it look nice! Cut the fan cable, and cut the mains supply cables to the PCB.
The mains in is simply reattached to the existing A4k mains in and switch.

BeQuite-A4000PSU-7.jpg

Pillars installed, with spacers to get them to the correct height.

BeQuite-A4000PSU-8.jpg

PCB installed. And the ATX cable has been replaced with the original A4k power cable.
You need a very good soldering iron to remove the old ATX cables. A PS-ON to GND cable makes sure the power supply powers up when the mains power switch is switched.

BeQuite-A4000PSU-10.jpg

 Nearly there.. Mains reconnected.. Just need to reinstall the on off switch.

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A screw.


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Mmmmm yummy.

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This is the first time this PSU has been opened since it was built. The dust in here is half my age. :( Oh dear, I'm old.
I've unplugged the mains in, and removed the on off switch, as I will use all of this with the new PSU.

BeQuite-A4000PSU-6.jpg

 Using one of the existing PCB mounts I've marked out three more positions for the other pillars.

BeQuite-A4000PSU-13.jpg

All of the pillars need to be flush on the bottom of the case.

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Fan reconnected.. And some special tape to insulate the PCB edge from the chassis.


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And finally, some heatsink compound ready to accept the chassis.

BeQuite-A4000PSU-14.jpg

That's better! The original Amiga PSU was outputting 11.3v on the 12v rail, and 4.7 on the 5v without load.


If you are thinking about doing this yourself, think twice. These are switch mode PSU's and are very dangerous.
Don't fiddle with this stuff if you don't understand the risks.