+5VDC Computer PSU question

[TomWaterman]

Hi!

Can anyone help me? I need a +5VDC supply for testing an evaluation board I got from TI.

I only have an old computer PSU kicking around as a possible 5V source.
I have been told it will only work if the PSU passes its internal checks with reference to the PowerGood pin that normally connects to the motherboard.

Do I link the PowerGood pin to PSU ground to 'pull it' down so I can get power to the other pins, notably one of the +5V pins to connect to the board?

Anyone know how that system works? I don't want to fry my evaluation board before I listen to it....

Cheers Tom

 

[gyraf]

Old AT-style psu should work as-is.

Newer ATX-style psu's may need some strapping to run.

Power it up and measure what comes out..

Jakob E.

 

[TomWaterman]

Cheers Jakob!

Problem is - I don't have a multimeter to hand, so I have no way of knowing exactly what comes out....I just figured it should be a pretty constant +5V otherwise it would kill the fragile components on a motherboard.....

I'm pretty sure this PSU needs strapping, so am I correct in thinking I need to strap the PWRGD to ground?

Thanks for your help
Tom

 

[tmbg]

Go to the thrift store and dig around in the inevitable box of wallwarts untill you come up with a 5VDC supply

 

[TomWaterman]

Thats a good idea but it still costs money.....I'm trying to be a skinflint here, typical student!!

Maybe I'll look around town in a bit.....

Cheers Tom

 

[tmbg]

wallwarts tend to collect amazingly fast, at least for me... if you go to the right place, you can often get them for a buck. Much cheaper than a computer PSU, and much easier to deal with.

A computer PSU would make a decent bench supply, if it's the old AT style, the new ATX require all sorts of jiggery pokery to get them to power up. But beware that they're switching-type supplies, so they'll be noisy as hell.

 

[TomWaterman]

Cheers tmbg,

the power supply will only be used for digital and logic testing etc, I have a proper bench supply for audio rails which I hope is less noisy.

I'm going to look for a wall-wart now, but its a lot harder to find 'thrift' shops here in the UK compared to the states...at least where I live!

Tom

 

[PRR]

No, don't strap Power-Good to ground.

Most AT-type (two inline 6-pin mobo connectors) power supplies need no strapping, but DO need a load. A big old hard drive is usually ample.

I would not go hay-wire like this without a voltmeter.... the output of computer supplies DOES vary, especially when mis-loaded, and you could smoke that valuable evaluation board.

 

[owel]

First of all, you need a tester/multimeter. Should have bought a tester before that evaluation board.

You can rig a simple 5volt regulator using a 7805 and a few resistors and a big heatsink. Then use a 12V or whatever 5V+ wall wart.

 

[TomWaterman]

Thanks for the tips guys........

I didn't buy the evaluation board, Rochey kindly secured it for me! Thanks again Rochey :thumb:

I really really need to buy a multimeter, gonna get a Fluke soon I think, didn't want to get a cheap one from Craplins as its wasted ££££ better invested into a quality unit.

I actually can't do anything with this board anyway right now, as the software app that is used to control it happens to be Windows95/98 only!!!

I'm running XP and am now on the hunt for a machine I can nick for a while to listen to this danm board!

Thanks for all of your tips, I will hold off until I can scam my sisters 98 machine.....(edit: and buy a meter!)

Cheers Tom

OH BTW its the evaluation board for the PGA2310 volume control chip mentioned in the digital attenuator thread.