It is a little known fact that some of these modems need an AC 12 to 15 Volts supply at around 250 mA. Supplying them with DC will lead to disaster since the rectifier circuits develop both +ve and -ve voltage rails for the chips and the RS-232 interface. Those circuits need an AC supply to do this.

I opened up the plug power brick and removed the transformer and found a place to mount it inside the ATX power supply. This needed a mounting beam to suspend it above the PCB.

The beam was fixed to the front and back panels of the power supply (the right hand long aluminium piece in the photo) and the transformer (not illustrated) was then fitted on the beam. The primary side was wired across the auxiliary connector and the AC low voltage output cable was organised to exit with the rest of the wires from the front of the power supply (lower right corner of the photograph). I also changed the fan for an Evercool and ran its supply wires out through the same route so that I could take charge of its running speed and hence noise.

Here is the modem tray which is 20SWG aluminium alloy sheet folded up to be the exact width of the chassis of a 5.25" drive (5.75"). The mounting pillars have been fitted and a red fibre washer added to each because some tracks run fairly close to the holes on the PCB.

Again more red fibre washers fit on the threads above the PCB. (This photo was taken before the top fittings were added.) Note the fixing holes at the front of the vertical sides. These are for the front panel screw fixings. The head of the left hand one can be seen below.

The front panel itself is a spare blanking panel from another case (I fully expected it to be only a test piece but all went well and it finished up being the real one! Unfortunately, it has a pig-skin grain which is a little coarse compared to the other panels). Its fixing screws are in holes drilled in the original latch parts.

The original window was easy to remove from the original case and I carefully marked out the cutout needed to mount it in the front panel. After drilling and filing the slot, the part was virtually a light press fit and I secured it with a dab of hot-melt glue on each of the inside corners after spraying the panel to match the metallic powder blue of the computer.

The photo above also shows the connectors. The two black and silver ones at the near left corner and pointing straight into the left chassis side are the Mic/Spkr connectors which I never use. Along the rear edge are: the low voltage AC power input connector, the RS-232 serial port 9 pin D-Type connector and the phone lead connector. The serial cable and the phone lead are routed through the case and emerge through a hole in the computer case rear panel. The serial cable is plugged into the conventional external serial port. Both phone and serial cables are secured with a tiewrap onto the rear of the case to prevent their internal connectors getting pulled out.

Here's how it looks in the bottom 5.25" slot of the new case.