I recently found an ATX Power Supply which offers a quite a decent power at its output. But most importantly it offers +12v, +5V, and +3.3V at its output which is very commonly used in electronics so let's turn this into a Lab Bench Power Supply!

Warning: If you have No idea about electronics then don't try this, AC Mains Voltage is fatal! especially with high voltage capacitor.

Step 1: Watch the Video !

if you don't want to read all the stuff you can watch my video on youtube

Step 2: Disassembly and Testing

Before you start opening the case of ATX power supply first keep the power supply unplugged to discharge those high voltage capacitors.

Then open the case of ATX power supply and clean the internal electronics with a brush or blower.

Now we first need to check if the power supply is in working condition. To check that take 20-24pin connector and connect 14th pin i.e Green color wire to any of Black color wire Pin. If power supply's fan starts then it is in working condition.

Step 3: Trimming and Sorting

Now you can trim down the wires to an appropriate length because we don't need connectors. Once done Sort the wires according to color.

Red is +5 V

Yellow is +12V

Orange is +3.3V (Brown wire is voltage sense for 3.3V so connect it with orange)

Blue is -12V

White is -5V

Green is PSU On

I dont need -5V and -12V so I wont be using them.

Step 4: Drilling and Soldering !

Now drill holes for banana Connectors (Binding post) and attach them, Make sure they are tight or else they can short something in future.

Now strip all the wires and solder them in a group according to their colour. Now solder the entire bunch to the binding posts. Make sure to leave 2 Black wires,1 Red and 1 Green wire.

Step 5: Adding Dummy Load

To make sure our Power supply output is stable we need to add a dummy load, add a 5 Ohm 10w resistor to it. I don't have a 10W so I'm using two 10 Ohm 5W in parallel. Now solder Red and Black Wire across it. Don't forget to cover it with some tape, and place the resistor in the power supply case.

Now the only thing left to do is connect Green wire to Black wire so our power Supply is Always ON. You can add a Switch otherwise.