Building your own switching power supply from scratch is out of the question because of the complexity involved. What I've seen people usually do is take out the PSU board out of the metal case, cut off unnecessary wiring (extra Molex plugs for instance) and extend the leads on the tallest capacitors and MOSFETs with big heatsinks so that they can be laid down on their sides to reduce overall height - if you decide to do this keep everything well insulated, those capacitors can hold a nasty charge and keep in mind that most heatsinks will be at live potential so they absolutely cannot rest on top of a metal chassis or even touch each other. You might want to add insulating kits to each of them (mica plate + plastic washers) or replace them altogether with insulated tab versions.

Personally I'd look around for small power supplies used in slimline PCs or similar equipment - those are usually long and thin. Even a non-PC PSU (like from your satellite receiver) could be adapted to AT/ATX with a bit of soldering if the voltages & currents are adequate for a personal computer (which most likely are since that satellite receiver is pretty much a specialized computer).

DC-DC adapter used on MiniITX builds is probably your best bet, but they can be quite expensive.

Personally I'd look around for small power supplies used in slimline PCs or similar equipment - those are usually long and thin.

That's what I'd do too. I mean, with a fair amount of electronics skill it is possible to build a new PSU out of parts, but it's not really worth the time and effort when you can adapt something pre-made cheaply and easily. I'm not sure exactly how much space you have to play with, but knowing in general what satellite receivers look like, I'd start looking at things like 1U server PSUs, and Dell units from the smaller GX150 and GX260/270/280 machines... and then when you find something that will fit, just use one of the cheap ATX->AT adapters to hook it up.

I have the original PSU from the receiver, its a liteon PB-6540-1m. but the connector is not even close to standard, and it doesnt say which pin is which voltage.

it does however have ratings:
-5v==0.18A max
+12v==0.8A max
+7.5v==0.3A max
+5v==1.59A max
+3.3v==5.0A max
+1.8v==3.0 A max

but I dont have a multimeter.

and where I live I have a shortage of PSUs, so even having a spare normal power supply is not easy. all the PSUs I get are cheap and/or dead, so they are parts.

So get a multimeter. You can get one for less than $20 that will solve this problem for you, and it will become a valuable tool.

Heck, less than $10 probably!

Those current ratings look way too low to run any sort of desktop motherboard. I've got an old AT 200w PSU here that has 12A on 5V rail and 8A on 12V rail.

Maybe idf you used compact flash cards or SSD for your hard disk, no fans or optical drives and used a CPU known for power efficiency like a C3 you'd get away with it. Certainly any sort of 3d video card is likely to be out of the question.

Yeah, there's no chance that PSU would be any good for running a PC system. A 486 chip would suck up most of the 1.59A worth of 5V by itself, not to mention all the other parts that use the same rail. And 0.8A on 12V isn't enough to even spin up most older hard drives.

For a "new" power supply, this one fits the bill EXACTLY. You may want to look for one with a bit more wattage, but if you are conservative on your parts, then this one should work fine.

http://www.jameco.com/webapp/wcs/stores/servl … 10001_217306_-1

YOU WILL NEED A FAN!

Oh, you can get the connectors here: http://www.mouser.com/

The power supply's manual tells you exactly what connectors you need. (they are very standard)

Don't bother with the original psu, I suggest going diy the whole way even bread board if you have no choice but if there is enough room or find an itx unit you can move the internals from that into the receiver box. You might have to make your own mount points and use a cable adapter for the power from the wall to the receiver box but it should go pretty good.