Step #1: Identify the Wires on the 20 Pin (or 24 Pin) ConnectorPrevNext
- The wires on the main 20 pin (or 24 pin) connectors are color coded. These are the same for all ATX power supplies: 3.3V wires are orange; +5V wires are red; -5V wires (if they are present) are white; +12V wires are yellow; -12V wires are blue; ground wires are black.
- The green wire is the "power on" sensor. This wire is internally connected to 5V with a pull-up resistor. If you connect this wire to ground (any black wire) the power supply will turn on.
- The purple wire is the +5 "stand by" power. This outputs a 5V signal even if the rest of the power supply has not yet turned on, allowing you to power any circuit that might control the ON/OFF signal.
- The gray "power good" indicator is at 5V if each of the output wires is operating at the correct voltages.
- To make the connections easier to identify, I used colored markers to color code each slot on the 20 pin connector.
Step #4: Drill Holes for the Banana Jack Terminals and the Power SwitchPrevNext
- I used four pairs of Banana jack connectors for the outputs, so I marked eight locations evenly spaced on the top of the housing. Then I drilled holes that where just big enough for the mounting screws. I also drilled a hole for the power switch on the right side.
- Once all the holes are drilled, insert the switch and the power terminals and fasten them in place.
Step #7: Attach the Banana Jack Terminals to the HousingPrevNext
- I attached the banana jack terminals to the top of the housing in two rows. The red terminals are for the positive 3.3V, 5V and 12V connections; the black terminals are for ground.
- Insert the post of each terminal into the holes and tighten them in place with their screws.
Step #9: Connect the Wires to the Appropriate TerminalsPrevNext
- Connect the black wire to the first black terminal, then connect the other black terminals to the first one with short jumper wires. I also connected the wire from the power switch to the nearest black terminal.
- I connected the rest of the wires in ascending order according to their voltages. Begin with the 3.3V wire (orange) on the far left, then the 5V wire (red), the +12V wire (yellow), and the -12V wire (blue).
Step #10: If Necessary, Add a 10W Resistor to Meet the Minimum Load RequirementPrevNext
- Many power supplies will not stay on unless the output reaches a certain minimum power requirement. To test if your power supply has this requirement, press the power button and wait for a few minutes. If it shuts itself off, then you know that your power supply has a minimum output requirement.
- To take care of this, you can add a power resistor between the 5V terminal and ground. In most cases, a 10 watt 10 ohm resistor will work. In very rare cases, you may also have minimum output requirements on the 12V pin and the 3.3V pin. This will require additional power resistors.
- These power resistors create a lot of heat, so if you add a power resistor, make sure that your project housing has adequate ventilation. In some cases you may even need to add a small PC fan to help dissipate the heat.
Step #12: Add a USB Power Outlet (optional)PrevNext
- Another optional connector that you can add is a USB outlet. This will let you run any device that is powered by a USB port. To add this kind of connector, I recommend using a USB extension cord. Cut the cord in half — we want to use the piece with the female connector on the end. Next, separate the internal wires at the end. Strip the insulation off of the ends of the red and black wires and add a spade connector to each one. Connect the red wire from the USB cable to the red wire from the power supply. Connect the black wire from the USB cable to the black wire from the power supply.
- Once the wires are connected, mount it to the side of the housing. Trace the outline of the USB connector onto the side of the housing, then use a sharp knife or a rotary tool to cut it out. You can glue the USB connector to the side of the housing. I recommend using JB Weld, just like you did for the 20 pin power supply connector.
Step #13: Add Labels For Each Pair of TerminalsPrevNext
- To help keep track of the different voltage outlets, I labeled each pair of terminals. You can print out a simple label and attach it to the top face of the housing between the positive and negative terminals.