Hi-Power Mains Adaptor

Nearly everyone who owns a expanded "in-one" Amiga will know the situation. You've just bought a brand new addon for it, you plug it in but your poor old power supply hasn't got the reserves to cope with it, resulting in random crashes. The truth is the Commodore power supplies were only designed for a standard model, maybe with a low power HD inside. Nothing like the 060'ed beasts with 2gb HD's we see today! Luckily for you it's very easy to convert a PC unit to work on your Amiga.....

Before you start you must realise this is a one-way hack. Unless you are really talented, you cannot go back to your C= brick. If you mess it up, you will be even worse off, so it's worth a bit of time making sure you can do it.

Firstly take the cover off your Amiga unit. Try not to touch anything, as the capaciators (the large cylinder things) can hold mains voltage even when the unit has been unplugged for a while. It seems that every unit is different in the way the PCB was layed out, but all the wires for the Amiga cable should be close together. Chop these off, of if they are on pins through the board flex them until they snap, as this gives you a nice clean contact. Now open up the PC PSU you got hold of. Any old one will do, as long as it's "Standard". Basically, if it's 200, 220 or 230 watts and pretty new it'll be OK.

Open this up, again making sure not to touch anything just in case, and hold it with the power plug facing you. In the back right corner there will be a huge cluster of wires. Most of these aren't needed, you just need one 5V, one +12V, one -12V, one GND and one Earth. These are all marked on the PSU at the solder point. If there isn't an earth there, don't fret. Look near the power input and you will see a bolt welded to the case. This is the earth point. Just run a bit of heavy-duty wire from this using a eye connector, and this is your earth wire.

Now you have the wires you need, you can chop the rest off. You can either desolder them from the PCB, or cut the right down short and blob some hot-melt glue over them to make sure they don't touch. If you desolder them, make sure you don't drip solder anywhere, as this will completely destroy the unit. So, lets do a check. You now have a Amiga square-DIN power plug and cable, and a PSU with 5 wires coming out - 5v, -12v, +12v, GND and Earth.

Now you need a connector block, these are available from Auto shops generally. Put the PSU wires into the cells on this block and screw them down tight. Now use the diagram to work out which colour matches which wire. This may sound a bit dodgy, but you will have to look hard to find a supply that doesn't use these colours. In any case, the voltages are marked.

Just screw the appropriate wire into the appropriate hole on the connector block. Using the moulded part on the Amiga lead, fix the lead into the old wire exit hole on the PSU, and screw the supply back together. You now have one working supply! (Hopefully). You need to load it down to test it properly, but if you fix a multimeter between each pin and ground (the outer shield), the when you turn it on the power will peak just above the correct voltage and then drop. This is enough to test the right signals are present.

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