Power supply?

Short length of wire or a paper clip is all you need join the green wire in the ATX connector to any black wire...I do it regularly when i refill my pc watercooling, can power the pumps without starting the pc up, idea being check for leaks before running power through the main board and rest of pc :) If you wish to get fancy wire a switch between the green and black wire.. :)

Kim
 
yep, just connect the green and black wires. Most power supplies have a switch on the back these days to turn them on and off so there's no real need to add another one.

If you're only using it to power the charger having the charger connected while turning it on should provide enough load. I have a car light globe connected in place of a resistor in mine, but I use it as a general benchtop power supply for other things as well.
 
I assume you are looking for 12V.

A computer power supply can provide either 5V or 12V without further modification.

....but, you will need to bundle all the yellow wires to get the current you need to charge multiple cells, a single yellow wire will not provide enough current.

Here is the plug diagram to jumper the green wire to any black wire to get power to the power supply:

Just jumper 14 to say...13 and you can turn on the power supply.

z_mbconatxmain.gif
 
every modern ATX powere supply i have seen whether or not it had a switch on the back, still needs the "Power ON" pin grounded for it to run. that would be pin 14 on the motherboard connector and is usually a green wire.

additionaly some also require a slight load on the 5V supply a few mA will do. no need for huge resistors there. 500R 1/2W is enough in most cases

rick
 
Thanks All for the responses, I finished this up last night, and it works great so far. I'll use it to charge tonight and realy give it a good test.

One thing I noticed was the power light that was built into the supply flickers and is almost out when the green whire is grounded to turn the supply on. I do have a 5 ohm load on the +5V side, and get 12.5 volts on the yellow to black wires, but I remember that light staying solid when it was running before. have I done something wrong that might come back to bite me?
 
I need some help.

I just came back from Radio Shack with a pair of 10 ohm 10W resistors, hoping this would be the last piece of my power supply conversion. I soldered the red and black wires to one resistor and then connected the ps to my charger. The charger's blue LCD screen flickered on for half a second and then shut off. I tested the charger with a 12V SLA, and it stayed on, so I know the charger is still good.

I have all the yellow cables together as the +, and I have the single blue wire as the -. The single green and a black wire are wired together. All the reds are taped together, but they're not connected to anything. All the other cables were snipped and are taped together out of the way.

I tried a 12V fan last night as the load since I didn't have the resistor, but that also just made the charge flicker. Before beginning the conversion, I plugged the ps into a desktop computer, and it was able to boot the computer and start the drives spinning, so I'm fairly certain it works.

Does anyone have suggestions?
 
The blue wire is not a ground wire, it is -12V.

all the yellow wires together are +12V.

Attach all black wires together except one (to connect to the green)

Yellow wires are positive
Black wires are ground (or negative if you prefer)

there is a difference between -12V (blue) and Ground (black).
 
Here's what my PS looks like inside. Connecting the black and yellow as power for the charger didn't work either.
 

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  • PS.jpg
    PS.jpg
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As TPA said the blue is -12v which you won't use so best to cut it off too.
You probably put 24v into your charger by the blue instead of the back wire, but it sounds like it's still ok if it powers up from a SLA.
Have you got a multimeter to test the voltage across the yellow and black wires ?
It may be that your PSU isn't quite putting out enough voltage.
I've converted about 4 or 5 old PSUs and one of them would trip and turn off as soon as I tried to pull more than around 800ma from it. When I tested it with a multimeter it was only putting out around 11v and would drop down to 10 or so with an load and then turn off. Most are fine but you get the occasional dud, especially when pulled from an old computer that may have been scrapped for unknown reasons.
 
OK, some odd stuff - i connected my multimeter to the yellow and black wires before turning on the PS. I flipped on the PS, and it showed about 5V and quickly went down to 0. The 10 ohm resistor shows 6.3 ohm when connected to everything. It shows 10 ohm when disconnected.

I give up. I think a portable ps to go with my charger would be nice, so I'm just going to buy this one http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&Item=110345069152 . It's the cheapest and ships from California.
 
Have you got it running through a power board ? Mine often trips the surge protector when I initially turn it on and I have to reset it.
Try removing the resistor and see if it works, you wont hurt it.

All that said, if you're only using it to power a 50w charger the one you linked is a smaller, neater quieter power supply and isnt worth the messing around for $10.
 
ok, I figured out my problem with the light.
5 Ohms isn't enough load.
It is enough load to get it running, but it needs the load of the charger to work propperly.

Quick and dirty Wiring:


Yellow = +12V
Black = Ground
Load resister between Red (+5V) and any black wire.
Green wire connected to any black wire.

Ignore the other wires.
Unless it doesn't come on, then see the above links about the voltage sensor wires. those 2 will need to be hooked up.


Thanks all for the help, I now have Wall power for my charger!
 
Got mine done this morning. I spent too much time making it look good.
Too bad all I get is 10.9V where I expected 12V.
Oh well, I'll try testing before going any further with the next one.
PS_one.jpg
 
I tried mine again w/o the resistor as suggested, and it also registered 4.5V and then faded to 0. Would it make any difference to use both resistors together in series?

My charger is probably one day away, so I have one more day to test things with the computer ps before it gets shoved into a corner.
 
Zoot Katz said:
Too bad all I get is 10.9V where I expected 12V.
Click to expand...
Sounds like you ran into the same problem I mentioned a few posts back. I always test any that I plan to mod before I start "converting" them.
I had another strange problem with one I was planning to use as a permanant desktop power supply. When I opened it up and tested the voltage all was well, and when I hooked up my B6 lipo charger it happily pulled 5a through 2 of the yellow wires. I then cut off and insulated all the other unwanted wires and bunched up all the yellows and blacks. Putting it all back together I hooked up the lipo charger again and it shut down when it started to draw current. After alot of experimenting I found it would then only put out ~1 amp - set the charger to 1.2a and it would shut off. Strange...

yoyoman removing the resistors all together and power it up with the charger connected, it'll be enough load.

In related ATX-lipo charging news, inspired by methods' lipo charging adventures I was playing with an old PSU this arvo to see if I could directly charge my 6S lipo pack up to the 24.6v the PSU was outputting (through the yellow and blue wires)
It worked for minute, starting to charge up the pack at around 1.7a. One lead slipped off so I reconnected it only to find it was then charging at 3a. "hmmmm..." I thought to myself, only to be inhaling the magic smoke a 5 seconds later. So don't try that one at home kids :lol:
 
So is there anything special about the 10 Ohm 10W resistor. That would draw 500mA from the 5V line and use 2.5Watts right?

Would it work with a 1KOhm 5Watt power resistor which would just drawn 5mA? I have a couple spare of those but no 10 Ohm resistors.
 
Does powering up a server psu without a mobo - as discussed here... the same as a regular atx? A server's psu has a higher efficiency & power rating, and might be better to use. Like this Artesyn Power Supply 22911700 -
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190348872678&ssPageName=ADME:X:AAQ:US:1123

Curious to know since I haven't tried it, if there is a problem connecting the 3.3v,5v,12v in series of an atx, example:
Antec NEO ECO 400C 400W
Output: +3.3V@20A,+5V@20A,+12V@30A,-12V@0.8A,+5VSB@2.5A
http://www.newegg.com/Product/Product.aspx?Item=N82E16817371029

to produce a total output of 20.3v, 20A limit
 
I am going to use an old 150w atx supply to run my 80w charger. I figured I would revive this old thread to ask a couple quick questions.
Do I hook the gray=power ok wire directly to an orange 3.3v+?
And also instead of running a resistor on a 5v+ wire can I hook the fan to a 5v+ red to act as a load ? I know it will run the fan slower but I am only going to pull 80w from the supply. It is rated 150w.
 
torker said:
Do I hook the gray=power ok wire directly to an orange 3.3v+?
Click to expand...
Neither. The power OK and the power ON are completely different. What you want to do is short the green power ON wire (only green wire in there) to any black wire (ground). Then, put on a load.

The problem that a lot of people on this (admittedly old) thread I think ran into was that some newer PSUs require a load on the 5V line (red) and the 3.3V line (orange) before they'll go to full power.

IDK if the fan will be enough load to bring it to the full power, and what some other people have said about the charger being enough load isn't strictly true. If the charger is on the 5V line, that would work (assuming the PSU only needs a load on the 5V), but if the charger is on the 12V line (more likely) it won't affect the PSU at all and it will stay in a low-power state.

Here's mine that I made:
http://www.thebestcasescenario.com/forum/showthread.php?t=23540
 
Ok, answered one of my questions. The fan when run off the 5v line will not load it enough. It only put out 8.7v :lol: So I found an old ballast resistor( used to use these on point style ignitions) It is only 1.2 ohms. It did the trick. Now outputs 12.29v 8) I found a link where if a 10 ohm didn't work ( output still too low) that 2 x 1 ohm in series would work to bring the output up but create more heat. I just used it because it is all I have handy. It did get pretty warm but will it work?
12ohm.jpg
 
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