Introduction: Another Computer Power Supply Mod

Unused computer power supplies are pretty much every where in labs. Unfortunately, they are not very useful since their wires are designed for attachment to computer components. I am a big fan of banana connectors in the lab and this Instructable shows how I converted an old computer power supply to a new fixed voltage lab power supply.

Step 1: Tools and Materials

Step 2: Power Supply Prep

There are a lot of methods to making a lab power supply from a computer power supply and one technique involves opening it up. I'm not too keen on this idea as it involves a lot of work (I've tried it before). So, I decided to not bother with opening up this power supply and just convert the wires to banana jacks. Thankfully banana connectors come in lots of colors. This allowed me to select the banana connector colors to have the same colors as the wires from the power supply.

So in this step I just cut off all the connectors to the power supply and evened the wires up.

Step 3: Enclosure Prep

Since I didn't want to open the power supply, the idea was to now take the wires and solder them to banana jacks housed in an external enclosure.

Figure 1:
I first measured all the wires coming out of the power supply and made an appropriately sized hole in the small aluminum enclosure using the nibblers. I used my needle files to make sure that my hole didn't have any burrs on it that could cut me later.

Figure 2:
I then measured out the placements where I wanted to put the banana jacks. Using the hand punch, I punched the largest hole I could with it. Unfortunately the hand punch I have does not make a hole large enough to fit the banana connectors. This meant that I had to use my deburring tool to remove enough material from the hole so that the banana connectors fit. Once they fit through the hole, I tightened them in place with the supplied nut.

Figure 3:
I then mounted the switch and an extra LED to the aluminum enclosure.

Step 4: Wiring

Wiring is a bit of a pain. I didn't get rid of any of the wires from the power supply which means that there were a lot of them to deal with. But, before dealing with the wires, I mounted the aluminum enclosure to the power supply by using the double stick tape.

Step 1:
Using the tie wraps, I collected all the similarly colored wires together. Except for the brown wire which should be tied in with the orange wires. The purple wire doesn't do anything so I used some heat shrink to keep it from shorting out. Reserve 2 of the black wires from being put in with the rest.

Step 2:
I then soldered the wire mases to their appropriate color coded banana jacks.

Step 3:
I soldered the green wire to the middle terminal of the switch and used one of the black wires to connect to one of the other terminals on the switch. Since the switch is a SPST, it doesn't matter which terminal the black wire went on.

Step 4:
I soldered one end of the resistor to the grey wire and then the other end of the resistor to the red wire on the panel mount LED. The last reserve black wire is connected to the black wire of the LED. I also used some heat shrink tubing to prevent any shorts from occurring from connecting the wires together in this step.

Step 5: Finish

The final product doesn't look pretty since it does have a bunch of wires hanging out of it. But, it does work and can be used as a fixed voltage source in the lab.