MP3 Player case construction details

Here are some details of the case I made for the MP3 player. Unfortunately I did not take any pictures whilst I was making it, but the pictures here show most of the design points.

The case is a metal box made from 0.030" sheet steel that I happened to have. It is only a little bigger than the motherboard, and built to fit around the parts I had. If I made another one it would be different.
The box comprises three pieces: the chassis, the lid and the end panel. The chassis is 1" longer than the motherboard, to accommodate a fan at one end, and is just tall enough to allow the ISA riser card to fit in when the lid is closed. The lid is hinged, and has a lip which fits over all three sides (including the end panel). It is necessary to make the end panel separately as the expansion cards (sound, VGA and Ethernet) must be attached to the riser card and motherboard first, and it is not possible to slide the assembly into the box as the connectors (VGA and MIDI port) get in the way. This also means that if I change the cards I am using I only have to make a new end panel, not a whole new box.
Inside the box, the motherboard is bolted directly to the bottom panel, with 1/4" spacers keeping it from touching the metal. The rear edge (with the keyboard connector on it) is aligned with the inside edge of the short, open end of the box, and the right edge (with the SIMMs adjacent) is aligned with the long edge of the box, away from the hinge. There is a gap between the other edge of the motherboard and the inside of the box, because the ethernet card is slightly taller than the distance from the riser to the edge of the motherboard.
In addition there is a small metal plate which supports the hard drive. It is mounted to the edge of the box and to two spacers from the motherboard mounting screws. Finally, the power supply is bolted to the lid, where it falls into place just above the CPU and the on-board regulators at the lower left of the motherboard, and adjacent to the fan in the case.
Adding the hinge to the box was an unnecessary effort, I think a separate lid with a lip all around would have been simpler. Also, the PSU should be mounted in the same way as the hard drive, on a bracket inside the box, as it is hard to lead the cables around the hinge.

A view inside the box, showing space for the hard drive. The motherboard is already in place, and the two spacers (with washers on) are visible in the foreground. The two holes in the closed end panel are for screws to support the other end of the HDD mounting plate. Also visible is the fan, power and IDE indicator LEDs and a strap which prevents the lid opening too far.
The 2.5" laptop hard drive I used, mounted on a metal plate. The drive has a 2.5" to 3.5" HDD cable adapter plugged in so it can be connected to a standard IDE cable. This image shows the 'shock mounts' I used, similar to Hugo Fiennes original MP3 mobile project. Basically two grommets either side of the mounting plate with the mounting screw running through them. I doubt it makes a difference, but it looks nice.
The last steps of assembly.
Hard drive in place.
All cards in place, the end panel can now be screwed on.
The end panel has the serial port and power inlet connectors already affixed, and space for the parallel port if needed later. The MIDI and VGA connectors go through holes in the panel, and have additional fixing screws (also used for cable attachment).
The PSU bolted to the lid, with 1/4" spacers.
The XLR plug just fits in the space above the keyboard connector, but it's a bit cramped in this corner of the box.
Assembly complete!
The finished project, rear panel with fan inlet and LEDs.
The finished project, front panel with power inlet and connections for keyboard, VGA, audio, ethernet and serial.

Next: Installation in the car

Š2000 A M Errington