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How to convert an ATX power supply to rc use - 4/8/2007 2:04:20 AM   
hands without shadows



Posts: 5523
Joined: 11/23/2005
From: denfield, ON, CANADA
Status: offline 		After posting this a few times I figured it was time to do a proper write up with pics.

How to convert an ATX power supply to rc use

Step 1. Collect Required Materials

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Step 2. Case Design

Take the cover of your power supply, there should be 4 philips screws holding on the top. Short the two big capacitors with a screwdriver or the big resistor so you dont kill yourself. Look for a good section of room where you will be able to hide wires and have the bottom of your banana jacks not touch anything. Then mark on your case where you will mount your banana jacks. The amount of banana jacks you use is up to you, I used four commons, two +12v, a +5v, and a +3.3v. To run a charger all you need is a common and a +12v but I wanted the option to run two chargers, test radio equipment, and have a +3.3v for labs.

http://i155.photobucket.com/albums/s283/HandsWithoutShadows/2-1.jpg
http://i155.photobucket.com/albums/s283/HandsWithoutShadows/2-2.jpg http://i155.photobucket.com/albums/s283/HandsWithoutShadows/2-3.jpg
http://i155.photobucket.com/albums/s283/HandsWithoutShadows/2-4.jpg

Step 3. Cutting the Case

Cut out holes in the case to mount your banana jacks, switch, and led (switch and led are optional). I suggest you buy the banana plugs from radio shack and buy single ones instead of buying connected ones like I used, these ones are hard to mount, its not that I suck at metal work its just that drill bits wont drill straight when metal is this thin.

http://i155.photobucket.com/albums/s283/HandsWithoutShadows/3-1.jpg

Step 4. Completing the Case

Mount your banana plugs, switch, and led.

To make the banana jacks I used fit tightly you have to shave down the ridge on one half of the plug. I shaved down the black ones because they will be mounted inside the case.

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Step 5. The Electronics

Look at the big 20 pin plug and see if any of the pins have 2 wires going to it. One of the orange wires in the corner should have a light orange or brown wire connected to it. You may also have light red and yellow wires connected to regular red and yellow wires. These light (or brown) wires are called sense wires and must be connected to their darker coloured wires for the power supply to function. Whether you connect these separately and heatshrink them or connect them to the banana plugs is up to you, I connect them to the banana jacks. You have to connect the sense wires whether you use those voltages or not. Remember what sense wires you have and go ahead and cut of all the plugs, dont cut the wires so short that you cant connect the banana jacks but dont leave them full length either or they wont fit in the case.

Solder a red wire and a black wire to opposite ends of the big 10 watt, 10 ohm resistor. Heatshrink the ends and mount the resistor using zipties in the path of airflow. This adds a small load to the power supply which it needs to function.

Next solder 3 black wires to a banana plug, this will be common or ground, I have 4 commons. To have +12v solder 3 yellow wires and, if you have one, the +12v sense wire (light yellow) to a banana plug, I have two +12v lines. To have a +5v line solder 3 red wires and, if you have one, the +5v sense wire (light red) to a banana plug. Finally to have +3.3v solder 3 orange wires and the +3.3v sense wire (light orange or brown) to a banana plug. You dont have to use 3 wires for each plug but use at least 2.

Soldering to the plugs I used is a royal PITA so I soldered my wires to small spade terminals and bolted those on.

Optional: Solder a black wire and the green wire to the switch, if you dont want to have a switch solder the green and black wires together and cover the joint with heatshrink. The green wire must be grounded for the power supply to turn on.


Optional: Solder a 220 ohm resistor to the led cathode (-) and solder the other end of the resistor to a black wire, solder the anode (+) of the led to the gray wire. This will function as a power on light. If you don't want an led clip the gray wire short.

The colours arent as I described because I used extensions, you cant see the resistor because I covered it with heatshrink.

Check to make sure you connected everything (especially sense wires) and cut all the remaining wires short, cover the ends with heatshrink so that nothing will short inside the power supply.

http://i155.photobucket.com/albums/s283/HandsWithoutShadows/5-1.jpg
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Step 6. Reassembly and Test

Carefully fit all the wire inside of the power supply and position the case on (it helps if you didn't use long lengths of wire and ziptie all the wire into a big bundle). Screw in the 4 screws that held on the case, plug it in, and turn it on. The led should light up and the fan should start running. If you didnt use a switch or led the fan should come on when you plug it in.

http://i155.photobucket.com/albums/s283/HandsWithoutShadows/6-1.jpg

Step 7. Final Check

Hook up a multimeter to all the different combinations and check voltages, your exact voltages probably wont be the same but they should be close.

http://i155.photobucket.com/albums/s283/HandsWithoutShadows/7-1.jpg

Some Basic Troubleshooting

Nothing turns on
-check connections, especially sense wires, switch, and resistor connections
-check if there is a switch on the back of the power supply

No voltage on some or all lines but fan turns on
-check banana jack connections

Led doesnt light up but fan turns on
-check led polarity

Burning smell
-you messed up and let the smoke out


Please use common sense when doing this. Dont do this if you dont feel comfortable with any of the steps. Dont blame me if you screw up. If you want to post this anywhere else you can do so without contacting me but please give me credit.

If you dont feel comfortable doing any of this dont do it, r/c fan-addict's method is much easier and safer.

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< Message edited by Nathan -- 2/3/2008 2:43:06 PM >

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RE: How to convert an ATX power supply to rc use - 4/8/2007 2:20:11 AM   
R/C fan-addict



Posts: 3459
Joined: 12/4/2005
From: Worcester, MA, USA
Status: online 		okay HWS asked me to post up my way of the same procedure. Using my method will allow you to not have to open the case. Pretty much what you do is you snip off all the connectors except for the 20/24 pin (the biggest one). Then you isolate all the yellow wires and all the black wires. Strip the ends of all the wires, twist them together, and put a dab of solder on the end. Then solder on your banana clips or if you want to go alligator clamps then just do nothing. Instead of the resistor and jumper wire you can instead use a powersupply tester. Step 1: buy a PS tester. Step 2: plug it into the 20/24 pin connector. Step 3: attach it to your PS and make sure it has good airflow since it is a resistor and it will get hot! That's it. A PS tester will run you about $5-8, if you pay more you're probably buying one with a voltage tester on it or some other completely useless crap. Just get the cheaper version, it works well. So there you go, the PS costs you $20 and another $5 for the tester and you have a fully functional R/C powersupply for $25. Sure beats paying $100 at the hobby store!

BTW: I know this is my first post in a long time, I kind of left RCU and I'm not really going to come back at least soon. I only posted this because HWS asked me to.

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RE: How to convert an ATX power supply to rc use - 4/8/2007 2:22:50 AM   
Andrew


 

Posts: 1818
Joined: 2/4/2003
From: Murray, KY,
Status: offline 		How to convert an ATX powersupply

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RE: How to convert an ATX power supply to rc use - 4/8/2007 2:23:33 AM   
hands without shadows



Posts: 5523
Joined: 11/23/2005
From: denfield, ON, CANADA
Status: offline 		Thanks RC, I appreciate it. I hope you come back sometime, you were always a great help.

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RE: How to convert an ATX power supply to rc use - 4/8/2007 2:25:42 AM   
hands without shadows



Posts: 5523
Joined: 11/23/2005
From: denfield, ON, CANADA
Status: offline
quote:

ORIGINAL: Andrew
How to convert an ATX powersupply


Unless you read the design guide update carefully that method doesnt work because it doesnt refer to any sense wires besides the 3.3v sense wire (brown or light orange).

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RE: How to convert an ATX power supply to rc use - 4/8/2007 4:13:24 AM   
Andrew


 

Posts: 1818
Joined: 2/4/2003
From: Murray, KY,
Status: offline
quote:

ORIGINAL: hands without shadows

Unless you read the design guide update carefully that method doesnt work because it doesnt refer to any sense wires besides the 3.3v sense wire (brown or light orange).


Did you read the last paragraph in the design guide update? I suppose the assumption was that you would read the section on remote sensing carefully -- it does reference sensing on the +5v and +12v rail. I have also seen one supply with a sense wire on ground.

I've converted around 80 or so supplies and run latch and voltage level tests on well over 200. There is a lot of variation across models - some supplies will latch and hold without a preload; some will not. A few will run without reconnecting the sense wires; the majority will not. Stability under load varies considerably -- Antec and Sparkle have performed well. To cover all the bases in the conversion process places some burden on the reader to be equally diligent.

If there is mis-information in the conversion, I would appreciate knowing.

andrew


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RE: How to convert an ATX power supply to rc use - 4/8/2007 4:37:08 AM   
hands without shadows



Posts: 5523
Joined: 11/23/2005
From: denfield, ON, CANADA
Status: offline
quote:

ORIGINAL: Andrew
quote:

ORIGINAL: hands without shadows
Unless you read the design guide update carefully that method doesnt work because it doesnt refer to any sense wires besides the 3.3v sense wire (brown or light orange).


Did you read the last paragraph in the design guide update? I suppose the assumption was that you would read the section on remote sensing carefully -- it does reference sensing on the +5v and +12v rail. I have also seen one supply with a sense wire on ground.

I've converted around 80 or so supplies and run latch and voltage level tests on well over 200. There is a lot of variation across models - some supplies will latch and hold without a preload; some will not. A few will run without reconnecting the sense wires; the majority will not. Stability under load varies considerably -- Antec and Sparkle have performed well. To cover all the bases in the conversion process places some burden on the reader to be equally diligent.

If there is mis-information in the conversion, I would appreciate knowing.

andrew



I meant that the sense wires are not mentioned in the general conversion, just in the design update.
In the few psus that I have converted I have never seen a sense wire on ground, it's interesting that it's there but I see no need for it, Ill edit my write-up (again) and add that. As far as I know all ATX power supplies require a load to function while the older AT power supplies do not, are you sure you didn't test AT ones? Please let me know so I can add that. Thanks for the info hat some psus will work without connecting the sense wires too, Ill add that in there too.

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RE: How to convert an ATX power supply to rc use - 4/8/2007 7:18:17 AM   
Andrew


 

Posts: 1818
Joined: 2/4/2003
From: Murray, KY,
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quote:

ORIGINAL: hands without shadows

In the few psus that I have converted I have never seen a sense wire on ground, it's interesting that it's there but I see no need for it, Ill edit my write-up (again) and add that.

As far as I know all ATX power supplies require a load to function while the older AT power supplies do not, are you sure you didn't test AT ones? Please let me know so I can add that.


I would not bother with adding a comment about a ground sense wire -- in probably 1500 supplies I've looked closely at, I can only recall one -- an offbrand. I don't know why it was added or what its function would be.

The majority of ATX supplies do require a load, but some will latch without a load. I got in some of the new large fan 300W Sparkles the other day that latched without a load -- measured voltage was 12.3v on the 12v rail. However, I still recommend a preload since it helps stabilize the 12v rail when under load.

I crack hundreds of boxes a year in my work -- we keep a couple of AT supplies on the shelf for Show and Tell, but we haven't had an AT box in inventory for 7 or 8 years.

andrew




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RE: How to convert an ATX power supply to rc use - 4/16/2007 11:44:41 PM   
GTB


 

Posts: 464
Joined: 4/3/2007
From: port St Lucie, FL, USA
Status: offline 		Were is the battery for it?

That's not a power supply if you can't use it anywhere.

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RE: How to convert an ATX power supply to rc use - 4/17/2007 2:39:03 AM   
hands without shadows



Posts: 5523
Joined: 11/23/2005
From: denfield, ON, CANADA
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quote:

ORIGINAL: GTB
Were is the battery for it?

That's not a power supply if you can't use it anywhere.


It plugs into a wall......

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RE: How to convert an ATX power supply to rc use - 5/9/2007 5:33:32 PM   
healthyfatboy


 

Posts: 155
Joined: 11/25/2005
From: Norman, OK, USA
Status: offline 		Will an ATX Switching Power Supply work for this mod?

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RE: How to convert an ATX power supply to rc use - 5/10/2007 9:05:27 PM   
Gigaah


 

Posts: 111
Joined: 1/9/2004
From: , WI, USA
Status: offline 		What do you guys think of something like this? All the jumper and resistor hocus pocus wrapped into a neat package.
I made a couple for friends and myself. The unit below would be a 10amp version due to the binding posts rating, and Its only using the one yellow wire from the 20 pin connector.
This particular one is only wired for 12volts. Has an LED so you know its on. This one has no switch because we just unplugged the thing when its not in use.
I wonder if others are interested and if its worth my time to offer somethiing like this since I don't know what people would pay for it.



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