IEEE 1394b Project

Last Updated 2005/02/15
IEEE 1394b Custom Drive Case

I was looking for an inexpensive way to expand storage on my home theater PC. The four 200GB drives pictured to the right, when installed in the PC, created to much heat. The Dign HV5 case I have is not well ventilated, so those drives heated the case at least 15C above an idle temperature of about 32C.

Part of my requirement was a slim, rack mountable and relatively attractive case. You can see it to the right viewed from the back without the top installed.
At the local Jaycar (an Australian based electronics
and hobby parts supplier), I found a PF-19 rack mount case.
PF stands for Packed Flat. It's Jaycar part number HB5120

It's a good idea to pick up a nibble tool while your there, to make quick work of custom holes in the back plate. Also at Jaycar I found a small open frame 120~240V PSU that outputs +12V and +5V DC. You can see it to the right in the above photo. I discovered later that it's somewhat underpowered for the four drives. If your going to try the same project, make sure your PSU has at least 4 AMPS on the +12V line.

Another item on your shopping list is an aluminum plate. At my local Dick Smiths, they have a 12" X 12" plate, just the right size for this project. I cut the the plate to fit to the side of the PSU. After test fitting the plate and marking locations of the mounting holes for each drive, I cut a fairly large hole for ventilation under each drive location. The case comes with adjustable rails for device mounting. I installed these to the extreme front and back of the case, then marked the aluminum plate where it will be attached to the rails with the screws and nuts included in the case package.

The PSU fit very tight into the side plate of the case, actually a bit too tight. It ended up deforming the stamped metal of the case about 1/16", making the top cover bulge slightly when attached. Now that the PSU and drives are ready, I started routing the wiring. The key here is to get round IDE cables that are very long and flexible. Carefully cut the boots from the ends for additional flexibility, they really aren't needed for proper function of the cable.

For the power cable, you could cut a standard cable from a old computer PSU if it were long enough and had enough connectors in the right place. I opted to make my own. I picked up the wire and bare connectors at Jaycar. Get 1 floppy drive style connector, 4 Peripheral Power connectors, a 120/240V switch, and a IEC 320 type AC recepticle. Get heavy guage wire to go from input to switch to PSU. Create the low voltage wire harness using the connector to wire relationship shown here to the right. The PSU will have the corresponding power/wire locations marked at it's screw terminals.

The key part to pull this all together is the IEEE 1394b IDE bridge board. This little beauty allows you to connect 4 IDE drives to a single Firewire 800/400 connector. The model I used in this project is FWB-IDE02. It supports 48 bit addressing, so drives over 137GB are recognized at their full size. It also has hardware RAID 0,1,0+1, and JBOD. You can read more about this device at ioi1394.com. By installing the PSU towards the front of the case, I was able to make enough room for the bridge board. The bottom-back rail in the case was at a perfect height to be used as a support for the bridge board. I added another rail in the back of the case that fit up against the PSU. This gave additional support for the bridge board. The floppy connector from the low voltage wiring harness connects to the bridge board, so make it the last connector in the line.

The back and front panels of the case are blank. Take one of the included back panels and position it where it would normally fit on the case, use the bridge board to mark the position of the back connectors. Remove the back plate that comes on the bridge board and use that to mark the final position of the holes on the case back plate. Drill a hole in the center of each marked position, and then use the nibble tool to create the final hole. A small file will smooth the opening. Use the same method to cut the AC receptacle and power switch holes.

My Conclusions:

The unit tested out fine, though the lack of ventilating fans in the case caused the drives to become much to warm for long term stability. Speed was great, I could play multiple DVD video streams simultaneously with no problem. Alas, due to the heat problems, and the slightly underpowered PSU (this caused no operational problems, but would most likely shorten the life of the PSU), I'm going to scale down this device to two drives, and add a couple small fans to the case. I'll also replace the 4 port bridge board with a two port version. This will make a great rack mount storage device for transitional media, extra PVR space etc.