External Drive Power Supplies?

3 replies [Last post]
Offline
Joined: Aug 3 2004
Posts: 74

I'm putting together my own external SCSI RAID and was wondering what I should do about a power supply. Most of the external cases I've seen have a power supply that's seperated from the drives, but not totally enclosed like in a Mac/PC. I've been planning on just using a mini or micro ATX power supply, but obviously I won't need the large connector that powers the motherboard.

The backplane I've got (using SCA2 drives) takes two standard hard drive power connections. I might be able to find a mini ATX that allows the motherboard power cable to be removed as on some of the Mac PS's. But I was just wondering if there was another option.

I haven't figured out what wattage i'm going to need yet but I'll probably just estimate and then go a bit beyond for future expansion.

I won't just be throwing this into a ATX case. I want to make something original that looks good and cools the drives properly. The backplane I've got can connect up to 6 drives and can be setup as 6x1, 3x2, or 2x3 (drives x channels). I want to do this right so that I can hold onto it for quite a while, just replacing the drives as SCA SCSI drives continue to fall in price.

My basic design idea is about the size of a shoebox. The backplane goes along the back side, and the case will sit horizontal rather than vertical. The drives will be laying on their sides and will be cooled by fans blowing air up from below. The whole thing will look somewhat like Apple's Cube (except I doubt it will be acylic and it won't be a cube) with air coming in from the bottom, passing over the drives and exiting from the top.

I'll post some diagrams later on. Advice on construction, materials, ect would be great!

-Tom

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.
DanR's picture
Offline
Joined: Jan 28 2004
Posts: 48
When I built my SCSI tower fr

When I built my SCSI tower from an old AT case I needed more power connecters than just cutting off the motherboard connectors and using those wires. On the power supply board, I discovered there were enough holes already there to connect my 8 wires each (originally it had three Molex connectors for drives) to the +12V and +5V plus all the grounds. The unneeded wires were just snipped at the source. Everything fit back through the original grommet.

eeun's picture
Offline
Joined: Dec 19 2003
Posts: 1891
AT PSU

If you use an AT power supply, instead of ATX, you won't have to worry about soft power on issues, plus AT supplies are plentiful and cheap. The local Sally Ann, Value Village, or whatever they're named in your neck of the woods, should have some old 486 boxes around - and there's your case, too!

BTW, I think I still have a cable from a SCSI array - it's got two Centronics DB-50s on a small back plate, and six or seven stnadard scsi connectors on a looped 50-pin ribbon. Yours for postage. Send me a PM if you want it (then I'll have to make sure I actually have it still! Wink)

__________________

"Give a man a fire, he's warm for a day. Set a man on fire and he's warm for the rest of his life."
(Terry Pratchett)

Offline
Joined: Aug 3 2004
Posts: 74
I searched a bit more and fou

I searched a bit more and found an old thread elsewhere that basicly asked the same question about the power supply. AT was the answer there too. Picked up a 200W from the local PC parts shop today for $7.

Here's a few drawings of how I think this thing is gonna look:

home.comcast.net/~tmbannon/scsi_case.pdf

At the moment I think I'm going to make this out of wood. I'll probably just stain and finish some pine. As of now the plan is to make a base and use spacers to mount two or three 120 mm fans as shown in the pdf. Taller spacers will be used to mount two horizontal aluminum bars above the fans. Holes will be pre-drilled so that screws can be inserted from below to hold the hard drives. As far as I know, hot-swapping drives isn't supported with my setup so I'm not worried about being able to pull them out quickly. Two more aluminum bars will be attached above the drives for added support. The could be achorred to the lower bars as I show in the PDF, but now that I think about it just screwing them to the 6 drives will probably be fine. I'm not sure how i'm going to mount the SCA backplane yet. I'll probably just anchor it to the the drive supports somehow.

The sides and top of the case are going to be assembled so that they lift off as one piece. Slits will be cut low on all sides for air intake and in the top for exhaust. These will be covered on the inside with either black mesh or speaker grille fabric. I'm going to open up the PS case and screw it to the top of the outer case (that's why the slits on top don't extend all the way across). The back of the PS will be mounted flush with the case, or maybe slightly recessed; it depends on how the SCSI ports need to be installed.

I'll print up a front panel to install next to Power and Drive 1-6 LEDs. A temp display isn't a bad idea either. That can all be mounted flush behind a piece of clear acrylic.

Im planning to order some Dynomat to line the inside surfaces with. It contains a thin aluminum layer so that should take care of shielding as well, right?

Any suggestions - technical or style? I really didn't want anything to be visible through the bottom vents, but I think with mesh in place you won't see much. Rounding off the verticle edges might make this thing look a bit better too.

Tom

Eeun - thanks for the offer, but I've got the SCA backplane for connecting the drives. What I need yet are two or three cables with one internal and one external 68-pin connector to go between the backplane and the exterior of the case. This is going to be much too fast for 50-pin cables anyway Wink I'm hoping to hit at least 200MB/sec. Why? Just for fun...