Computer Power Supply

[keko]

no, I don't want to use it to power py pedalboard. I know they are switching power supplies, and that switching won't do it. (why, BTW?)

I have several 'dead' ones, and they all have lot's of tiny transformes inside. Are they usefull, in any sense? How can you tell what is each, in terms of impedance, or whatever other measure?

[niftydog]

They will do it, they're just not always the best for audio applications. They can create a lot of noise due to the switching system that they employ; often the switching is done in the audible frequency range! They're not always well filtered or shielded either. Besides all of that, they're just overkill!

Dead ones can be fixed, usually fairly easily. If you are keen, or you know a computer/electronics geek, changing all the electrolytic capacitors often does the trick.

The transformers you speak of probably won't be particularly useful. However, the formers they are wound on are a potential useful item.


There's a magazine in Australia called silicon chip that just described a way of modifying computer power supplies to become HV supplies for tube circuits. If anyones interested, you should be able to go online and "buy" the article at http://www.siliconchip.com.au - though I havn't had much luck finding it as yet!

[travissk]

I think the Visual Sound OneSpot and Godlyke Powerall (pretty similar products) are both switching power supplies. They seem to work pretty well and get good reviews.

-Travis

[Paul Perry (Frostwave)]

I think we have had this issue before, but.... repairing switchmode supplies isn't always a walk in the park. often, some of the parts are connected directly to the mains :shock:  and another thing is, sometimes certain of the electros have to be special 'low impedance" types, otherwise they overheat & fail.
This month (July 2004) Silicon Chip mag in Australia has an article on converting PC power supplies to high voltage for valve amps. I wouldn't dream of doing it myself!

[niftydog]

get yourself an isolation transformer and an RCD and that considerably reduces the danger.

Besides, you never touch anything that's live, only work on it when it's disconnected and the worst you'll get is a boot from a cap.  :?

the low impedance caps you speak of are generally in the switching path, they are often quite easy to distinguish from the others. (brown usually, lots of markings, unusually large for their marked value)

If in doubt, leave them alone and change the others... or find a friend who has an RCL meter and check each cap.

Also, the amount of PC supplys I've fixed by changing the standby resistor is crazy.

I wouldn't try that silicon chip thing because it's a whole lot of stuffing around with transformers (been there, done that, sick of it) and I ain't a tube guy so...

Purpose built SMPSUs are often used for audio. Hell, this TV broadcast studio is practically held up by great piles of switch modes! Trouble is that most computer PSUs are cheap and nasty.