ATX power supply from 0...+/-40Vdc and 0...8A - diyAudio
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Old 22nd July 2011, 07:18 PM   #1
radio is offline radio  Macedonia
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Unhappy ATX power supply from 0...+/-40Vdc and 0...8A

Hello all !
I would be very grateful if you help to solve my problem positively.
It has the ATX - power supply 500W.
How does this ATX - power supply look you see in the photos!
From him i want to create an symmetrically regulated power supply: + / - 0 to + /-40Vdc?
IC it is LW4933 (MB1713.00)
Give help to change to do this for power supply to enable it to deliver the output of Us = + / -0 ....+/- 40Vdc and current from 0...8A.
thanks and cheers
Attached Images
File Type: jpg PATX-1.JPG (225.3 KB, 486 views)
File Type: jpg ATX (IC1).JPG (77.2 KB, 453 views)
File Type: jpg ATX-tablica.jpg (336.6 KB, 444 views)
File Type: jpg ATX-2.jpg (307.0 KB, 418 views)

Last edited by radio; 22nd July 2011 at 07:21 PM.
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Old 22nd July 2011, 08:32 PM   #2
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Just for starters,You will have to re-wind the transformer,and re-dimension the feedback resistors/circuitry.
(EDIT: and replace the rectifiers/caps with higher voltage parts.)
Then there's likely a power-good/watchdog chip in there on the output side that you'll have to fiddle with,or disable.
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Old 22nd July 2011, 08:36 PM   #3
Leon08 is offline Leon08  Germany
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There are many tutorials about how to convert ATX PS to lab PS, but I never seen a tutorial how to make a dual PS from this kind of PS.I think this is not possible because it provides maximum 12V and you need to change too many things to make it going to 40V.This IC (LW4933) is a PWM controller and you need at least the datasheet for it, to know what it can do.
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Old 22nd July 2011, 10:28 PM   #4
Leon08 is offline Leon08  Germany
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Hier is the schematic and exempel of such supply:
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File Type: jpg 8994786.jpg (77.7 KB, 342 views)
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Old 23rd July 2011, 03:34 AM   #5
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First off, you might want to try getting a decent platform if you want to use ATX supplies. That supply seems to be from the 90s or even earlier. Even a super-low end modern supply will be a better platform.

Not a chance that can do 500W.

Last edited by FenderBender11; 23rd July 2011 at 03:37 AM.
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Old 23rd July 2011, 05:18 AM   #6
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You can wire them in series provided you keep them isolated from one another.
Six of them would give you -+36 or 8 of them for +40v.
There is a web site that desribes how to do this.

jer
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Old 23rd July 2011, 05:39 AM   #7
radio is offline radio  Macedonia
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Quote:
Originally Posted by geraldfryjr View Post
You can wire them in series provided you keep them isolated from one another.
Six of them would give you -+36 or 8 of them for +40v.
There is a web site that desribes how to do this.

jer
I prayed to say where is that Web-site?
thanks
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Old 23rd July 2011, 12:38 PM   #8
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I found the link!
This is only one of many descriptions that I have found,But one of the best examples.
You just have to do a little searching.
I will keep searching for a few more in depth info.

Basicaly they all must be isolated from one another and only the mains ground (green) on the bottom supply is connected and the rest are not.
The mains ground (green) is only connected to the ground (black) one the output side.
With the mains connected (Black for hot and White for neutural) in parallel and the outputs in series.

Pretty straight foward.

The cases must be isolated from each other otherwise each sucsessive unit would be shorted thus the reason only bottom mains ground is connected.
As it is shown each case will exhibit the next step up in voltage ( in this case 5V)

Because it is this connection (mains ground (green)) that goes to the cases and must be isolated as the mains are already isolated from the rest of the circuit.

If I were to build one (as I have been planning to), I would take them apart and remount the boards in an insulated case and on some insulated standoff's to insure that no shorts could occur and blow the whole thing up.

The "Tower of Power" - A 30 Volt Computer Power Supply Stack

How to connect computer power supply in series or in parallel?

Last edited by geraldfryjr; 23rd July 2011 at 01:05 PM.
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Old 23rd July 2011, 01:21 PM   #9
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Here are a few more links to help get you going,just some more info and one is on parallel operation.

Good Luck!!!

jer


Computer Power Supply- ATX PC Pinouts, Schematics, Repair

PC Power supplies in series?

A simple high quality 12Volt 100Amp Power Supply- Part1 - Page 51 - RC Groups

Info: Can I use two Power supplies with one computer?? - Overclock.net - Overclocking.net

PC supply


P.S. Remember when doing this that the maximum current rating is only going to be what the smallest supply can provide, should you use supply's with unequal current ratings.

Last edited by geraldfryjr; 23rd July 2011 at 01:29 PM.
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Old 23rd July 2011, 02:01 PM   #10
wwenze is offline wwenze  Singapore
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This has been said already above, but it cannot be stressed enough, this thing does not supply 500W, probably not even 200W before it blows.

Sad to say, today there are still many power supplies that are grossly overrated. Particularly those that come free with the chassis.
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