PSU to DC powerstation Conversion

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Greywolf74

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PDU to DC Power walkthrough: (I Used a Dynex 500W PSU for this particular project)
THIS is the main link I used to get my information. This guy’s article is more of what’s what inside of a PSU and a little less like a walkthrough so I’m gonna try to summarize everything for you guys that just want a play by play and not so much of a lesson on what the internals of a PSU are and some various electrical information. I actually recommend you read this article first in its entirety before just running through my walkthrough.
FYI: (All wires colors should be listed on the side of your PC but here’s a list of important ones. The link above also goes into greater detail about the small handful of other wires in your PSU if you’re interested. The ones below are the only ones we are really interested in.)
Yellow wire = 12V first rail.
Yellow with black stripe = 12V second rail.
Red wire = 5V
Orange wire = 3.3V
Green wire = Power on wire
Black wire = ground

Parts you will need: (I actually got a bunch of my parts at radio shack…I suggest somewhere else, RS was expensive as hell.)
1) 1 PSU of the ATX variety (I suggest one with a fan in it, preferably an 80mm fan)
2) Pair of wire strippers, cutters, needle nose pliers, and crimpers
3) 10 ohm 10 watt resistor
4) 220 ohm ½ watt resistor (I believe it’s also ok to use ¼ watt also from what I’ve read)
5) Shrink tubing of varying sizes (I suggest buying a big size variety pack and a small size variety pack)
6) Banana Plug Binding posts (I used four sets because all modern PSUs have two separate 12V rails which we will harness. Also do not get the binding posts that the positive and negative are all one piece. Much easier to use the individual posts. If all you plan on doing is power one single LiPo charger from your PSU then you can simply buy one set of banana plug binding posts. I used four sets because I made connections for two 12V leads, 5V lead, and a 3.3V lead. I don’t know enough about electric RC’s yet to know exactly how this works but I know you can charge a 6V battery off of the 5V lead although unlike your charger it will not stop charging when the battery is full and I’ve read that you can use a combination of the 5V and the 3.3 Volt leads to break in electric motors. I haven’t done the research on this yet to find out how that’s done.)
7) Then you will need some banana plugs themselves for creating your own connections. (How many pairs of these you will need just depends on how many types of connectors you want to make. I suggest getting at least 2 pair because that’s what I use to clamp my alligator clamps to from my LiPo chargers.)
8) However many banana plug binding posts you bought, that’s how many 10-12 gauge Ring connectors you will need. (Whether you want to solder the wires to the connectors or crimp them is entirely up to you.) I only have a 40 Watt Soldering Iron so I crimped mine. If you are a newb to soldering like I am you will discover that you will need at least a 60 Watt, or maybe higher, soldering iron in order to solder wire that is 10-12 gauge in thickness.)
9) However many banana plug binding posts you bought, you will need twice as many metal washers. (The exterior diameter of the washer should be the same size as your ring connectors. The hole in the middle of the washer needs to be as close to the size of the post sticking out the back of the banana plug binding posts.
10) Liquid Tape or similar product.
11) At least a 40W Soldering Iron (If you’ve never soldered before (like myself) please look up some YouTube videos on:
a. How to Solder
b. How to tin wires
c. How to Solder wires
d. How to tin your soldering iron
(You will have to know these things. It’s not that hard to learn…try several practice pieces with some spare wire)
12) 63/37 rosin core solder (60/40 will work if nothing else is available. You may be able to get away with a 25Watts Soldering Iron if you happen to have or happen to find some 40/60 rosin core solder. They don’t manufacture that kind of solder anymore because of restrictions on how much lead they are allowed to put in solder nowadays. However if you happen to have a roll of it laying around, like I do, you could try and use it with a 25 Watt Soldering Iron because it will melt at a lower temperature than the solders that contain more tin.)
13) Four extra PC fan screws
14) 5mm LED (your color preference) (OPTIONAL)
15) 5mm LED mount (OPTIONAL)


STEPS: (One thing I want to address before proceeding. There are two very large capacitors inside your PSU and I suggest you stay clear of them. I’ve read that you can shock the living piss out of yourself if they discharge into you. I read several different articles concerning the PSU conversion and they all have these claims about the capacitors. No one seems to know how long they hold a charge after the PSU is unplugged so all I can say is be careful around them. I will say however I tried my damnedest to try and short out the two capacitors so they would discharge and no matter how hard I tried I never could get them to discharge so either you have to get down underneath them and touch the actual Soldering leads, which is virtual impossible to do cuz they are soldered almost flush with the board or they don’t hold a charge very long after unplugging the PSU. I can also tell you from experience that at one time or another I touched, either on purpose or accidently, nearly every component inside there and never got shocked. I can also tell you that every time I plugged it in to test something I let it sit for about 5 minutes before sticking my hands back in it just to make sure. I shouldn’t have to tell you not to stick your hands in there while it’s plugged in. If you do that then you are a dumb ass and shouldn’t be doing this mod in the first place :p )

1) Open the ATX Power Supply case and disconnect the fan. This connection is usually held in place by a little dab of rubber like material. Be careful removing this as you may actually pull the wires out of the connectors instead of separating the connectors. I suggest trying to cut or peel as much of the rubber coating off as you can before trying to pull them apart and try not to pull the wires themselves but the connectors instead.
2) Unscrew the fan from the housing. Along with that whatever type of screen they have in place should also come loose once you take out the fan screws.
3) Screw the fan back onto the top of the casing and make sure that the front of the fan (The part with the label on it) will be facing down so it will blow air from the room into the case. This is the opposite of the way the fan usually works in a PSU but it’s perfect for what we are doing. Not only do we want it to blow air into the PSU but we want the Fan sitting on top of the case instead of inside of it because you’re gonna need the extra space for all the wires.
4) Now using the extra set of PC fan screws screw the PC fan screen back down on top of the fan. That way you won’t accidently stick your fingers or have something fall in there and break the fan blades.
5) Now going back to the main part of the PSU you want to take and cut every single connector off of every single wire but don’t cut the wires short just yet. Only cut off the connectors at the very end.
6) Now fish the green “power on” wire and any black wire back through the hole and figure out where you are going to tuck them to keep them out of the way once you’ve soldered them together. Once you figure that out you can cut your green and black wires down to the appropriate size remembering to leave not only enough extra wire to solder the two together but also just a little extra cuz ya never know  Remember to put heat shrink tubing over your solder joint.
7) In this step I just want to point out that you should probably plug in your power supply and turn it on using the on/off switch on the back of the PSU. Also you should plug in your PSU and test it after every single modification you make to it just to see if it works or not. That way you don’t do like I did and get done with it and you throw the switch and nothing happens cuz you have some wires shorting out into the PSU. While we are talking about that I will go ahead and tell you that most PSU have built in safety feature in them that if a power wire is grounded out into the case the PSU isn’t going to explode in a wave of sparks. In fact it won’t even trip your breaker because they are designed to not even turn on it that happens. (If you are using a PSU that is so old or so cheap that it doesn’t have an on/off switch on the back of it then you will have to solder the green and black wire to a switch that you will have to go out and buy and mount yourself somewhere on the PSU. See the above mentioned link for more info on doing that. Virtually all PSUs made in the last decade are gonna have a built in on/off switch already.)
8) Next, what you want to do is solder your 10ohm 10 watt resistor to a red 5V Lead and a black ground. Doesn’t matter which end you solder to. Now before you solder you are gonna want to find a location on the side of the PSU that has all the holes in it for ventilation. Ultimately after you’ve soldered up your resistor you are going to zip tie it to the area of the PSU. I prefer to put mine toward the bottom to keep it out of the way. I’ve read that you should put heat sink compound on the side of the sandbar resistor that will be in contact with the metal but mine even hardly gets warm. I don’t think that is necessary but you may want to just for shits and giggles. Once you’ve got you location picked out then again cut you red and black wire to length leaving yourself just a little extra for margin of error. Remember to heat shrink both side of the exposed wire and solder joint.
9) Next thing you're gonna do is find a place to mount your LED mount. You can put it anywhere you want. Whatever way is the most visible. I put mine close to the power switch. Remember at this point before moving on to soldering the LED you slide the rubber grommet from the led mount over your leads on your LED so it will mount right. Upon first trying to determine how the LED mounted in the Led mount I thought it slid in from the front side but it does not. You push the LED with the rubber grommet already on it into the back of the mount.
10) Then you are going to solder a 220ohm ½ or ¼ Watt resistor to one side of the LED. It doesn’t matter which side.
11) Solder another red 5V wire onto the positive side of the LED and a black wire onto the ground side on the LED. Now LED are polarized so you need to make sure you know which lead is positive and which lead is negative. You determine that by looking at the base of the plastic part of the LED. One side will be round just like the LED (positive side) and one side will have a flat notch (That is the negative side). Remember to shrink wrap all the exposed wire and your solder joints.
12) Now you can mount your LED in the LED mount. Plug in the PSU and make sure it’s all working.
13) Now For this part you will have to figure out where you’re going to mount all of your banana plug binding posts. I chose to do mine in the mesh ventilation side of my PSU because it was the only spot that had enough room to hold all the banana clip binding plugs.
14) In order to keep from grounding out the positive leads of the PSU to the case you will need to figure out how to insulate the metal shaft of the binding posts. I did a two step process for added protection.
a. First thing I did is coated each hole in the mesh ventilation side with Liquid tape that I was going to be sticking a binding plug through. I put enough liquid tape to fill in each slot where a binding plug would go through. Now Liquid tape isn’t a precision instrument so I went back after it dried and cleaned up the surrounding holes with a xacto knife. (Got this idea from Squirrel after seeing his water proofing vids….props)
b. After cleaning up all the mess take a very small drill bit that is just a shade bigger than the binding posts and drill a hole right in the center of the dried rubber
c. Now take some small 1/8in shrink tubing and cut little 1/8 inch long pieces of it. Take your binding posts and put the first plastic washer (the binding posts should come with 2 of them, a tear drop shaped soldering tab, and two metal nuts. If you’re doing it my way you can remove the soldering tabs as this project uses crimped Ring connectors) on then slide your shrink tubing all the way to the plastic washer and heat it so it shrinks to the post for added insulation.
15) Now stick each binding post through the rubber holes one at a time. After the post is through then take your second plastic washer and put it on. Now put the first metal nut on and tighten it down as tight as you can without stripping anything.
16) Once you have all your binding posts mounted now you need to start cutting your wires to length and putting the crimped ring connectors on them. I had 11 yellow wires and 2 yellow and black wires. Now the yellow and black are on a separate rail which can handle 18Amps. The standard yellow wires only handle 15Amps so what I did was mounted 5 yellow and 1 black and yellow wires to a 10-12 gauge ring connector so that way the Amp load would theoretically balance at 16.5 Amps. Now after doing that twice that left me with one extra yellow wire left. Just set it aside and continue on. I put all of the remaining red wires on a ring connector and did the same for the orange 3.3v wires.
17) At this point you have all your positives done now do your negative wires the same way. I ended up with 18 Negative wires left so what I did was split them up and put 5 black wires on 2 of the ring connectors and 4 black wires each on the other 2 ring connectors. I used the five wire grounds for the 12V leads and the 4 wire grounds for the 5V and 3.3V leads.
18) Now that you have all your wires cut to length and have ring connectors on them the rest is simple.
a. Take a metal washer and slide down the binding post.
b. Put your ring connector on
c. Put a second metal washer on
d. Put your second metal nut on and tighten the whole thing down.
(I should mention at the stage to try powering on the unit after each pair of banana plug binding posts that way if something is grounding out and the PSU isn’t turning on you know which one needs to be redone. Otherwise you may be like me and get it all done and then try it only to find out it’s not turning out cuz something is grounding out on the case.)
19) Now if all of your posts are hooked up and the LED is coming on now you can take all the left over wires cut them to a length that will just lay across the PSU, heat shrink tubing around all of them to keep them together.
20) Hook up your PSUs fan connection and use a dab of liquid tape on the connector to keep it from coming apart like it was in the beginning.
21) Put the top half of the housing back on to the bottom half, screw it all together and presto! You’re done!!

Another Tip: I took the positive alligator clamps of my field chargers and coated all the bare metal except for the front edge and the inside to prevent it from grounding out on the negative clamp while hooked up to the PSU.

Here are some pictures of mine…

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MotoGod

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Nice! I may have to give this a whirl as well...I have a ton of Power Supplies laying around and my 23A Power Supply for RC is huge and heavy.
 

Greywolf74

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Well the PSUs wont handle 23A but theyre pretty stout
 

MotoGod

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23A is more than I need. It's just what I have at the moment, but it's like lugging around a packed suitcase. haha Heavy and huge.
 
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