Can you mod a computer power supply ?

[Tsanford]

I think he was talking about powering the whole PC from a linear power supply.

I too would like to try a linear power supply for an audio PC, Anyone know where to get the pinouts of the standard power supply connector and current draws mabye?

I may hook up a PC to my system if I could get that noise supply, I mean power supply out of there dont even want one near my other gear.

[Overd0se]

I too would like to try a linear power supply for an audio PC, Anyone know where to get the pinouts of the standard power supply connector and current draws mabye?

Current draw will be dependent on your hardware. Look at the outputs on some good quality PSUs for reference. The connector pinout will be in almost any motherboard book. I hope the diagrams make sense.

PIN out by number

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1 +3.3V           11 +3.3V 
2 +3.3V           12 -12V 
3 Ground          13 Ground 
4 +5V             14 Power Supply On 
5 Ground          15 Ground 
6 +5V             16 Ground 
7 Ground          17 Ground 
8 Power Good      18 -5V 
9 +5V             19 +5V 
10 +12V           20 +5V 


ATX connector (socket)

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[Reklats]

http://web2.murraystate.edu/andy.bat...java_table.htm

[Optical]

Yes, i have sucessfully modded a pc power supply for use with amplifiers, the directions are given in silicon chip magazine sept 2003 and another similar article july 2004.
I have only had the time to mod one so farbut it works great, it basically involves taking out the switching transformer, rewinding it for a new voltage you want and using a voltage divider back to the voltage sensor to keep it thinking its at 12V

get those articles if you can.

[jackinnj]

if you have to use a PC supply:

it can be done, but it is much simpler to use the outputs "as-is" and then use the high current outputs to drive a flyback-boost inverter and a flyback-boost-converter --

noisy, but it will work.

[gmarsh]

Originally posted by carlmart
Once I had an idea to build an external linear power supply for my PC, as at least the internal environment would be free of RFI. The switching design is very bad for audio, at least at such low pricing.

Has anyone tried such a thing? Is it worth it?

Carlos

I doubt it... most of the RFI generated inside a computer is from high frequency clocks going around the motherboard, hard drive actuators and other things, not the power supply itself. Even with a linear power supply, your computer and its peripherals will quickly throw noise on the power supply rails.

If you want better quality from your soundcard, you'll pretty much have to modify the soundcard itself.

[carlosfm]

Originally posted by gmarsh

If you want better quality from your soundcard, you'll pretty much have to modify the soundcard itself.

That's what I have.
I have a +/-15v linear PSU for the soundcard (actually, only for the op-amps, OPA2604s instead of the dreadful original TLO72s).
It's a humble old SB Live Value.
Better would be to power all the soundcard from external PSUs, but this one is not worth the trouble.
If you want good sound on your PC, you need at least a decent external soundcard.
Then, tweak it.

[Stocker]

Originally posted by MWP
Not for the PC its not worth trying.
Even though the power source may be smooth, the switch-mode psu's on the motherboard and other hardware will chop it up quite badly.

You could always find what voltages are being generated where, locally, on the motherboard, and make linear regulators for all of them, too...




Sounds (!) like a hassle to me.

[ecman]

Originally posted by Optical
Yes, i have sucessfully modded a pc power supply for use with amplifiers, the directions are given in silicon chip magazine sept 2003 and another similar article july 2004.
I have only had the time to mod one so farbut it works great, it basically involves taking out the switching transformer, rewinding it for a new voltage you want and using a voltage divider back to the voltage sensor to keep it thinking its at 12V

get those articles if you can.

Is it this article you are talking about ?

http://www.siliconchip.com.au/cms/A_102096/article.html

I don 't know yet how to take advantage of these.

A PC PSU can provide a strong +12 V but a weak -12 V.



Well maybe i must search for a chip that can feed with only one +12 V rail rather than moding the PSU.
Maybe an op amp for car audio. Cars bateries have (0,+12V)

Though the PSU obviously has the capacity to provide much various voltages, i don't see any simple way to have a symetrical one.

[Optical]

Yes thats the July 04 article, the October 03 article is better..

http://www.siliconchip.com.au/cms/A_30705/article.html

The +/-12V and 5V outputs are scrapped to make way for a new winding which is centertapped, so essentially you can wind on any voltage you like which the total power remaining at 200W (pr whatever), so you can work out the current draw you would expect for the voltage you want..
Once you have wound yourself the new transformer you put a voltage divider on teh output and take a tap of 12V to send back to the voltage sensor

the transformer winding process is the trickiest bit, the article explain it all very well though.. i would scan teh pages but i dont have a scanner