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Convert/adapt an old ATX Power Supply into a Bench Power Supply with (or without) 3D Printed Parts

Posted by jpluimers on 2018/11/16

An interesting idea, although I would slightly modify it so I can -12V and -5V as well and maybe other voltage combinations too:

They are based on these underlying links:

Note that some of the newer power supplies with 24-pin molex connectors do not give you -5V any more.

A few notes:

  • depending on the age, ATX supplies can get you these voltages: -12V, -5V, 0V, +3.3V, +5V, +12V
    • -12V and -5V have very limited currents
    • newer power supplies often do not have -5V (especially the ones having 24-pin connectors)
    • newer power supplies have limited +5V power, but higher +12V power
    • older power supplies have limited +12V power, but higher +5V power
  • always take pictures of all connectors and the wire colours connected to them before starting (especially before cutting any wires)
    • this allows you to find back:
      • non-standard wire colours
      • configurations not covered here
  • to get stable 12V, you need a 5V load of about 5W:
    • between RED (+5V) andBLACK (GND),
    • for instance with pin 3 and pin 4,
    • or over one of the molex/floppy connectors: pins RED-BLACK
    • as load,
      • use at least a 10V/10W resistor or 12v/10W halogen lamp
      • ensure they are cooled well
  • to get stable 12V, you need a 12V load of about 10W
    • between YELLOW (+12V) andBLACK (GND),
    • for instance with pin 10 and pin 17,
    • or over one of the molex/floppy connectors: pins YELLOW-BLACK
    • as load,
      • use at least a 20V/20W resistor or 12v/20W halogen lamp
      • ensure they are cooled well
  • if your power supply has a BROWN (+3.3VS),
    • then ensure it is connected to ORANGE (+3.3V)
      • as brown is the SENSING wire to check 3.3V is OK.
  • to turn the power supply on,
    • short GREEN (PWR_ON, pin 14) and BLACK (GND, pin 15)
  • to know when the power is on:
    • connect a LED via a resistor between GREY (PWR_OK, pin 8) and BLACK (GND, pin 7)
  • to know when there is mains power:
    • connect a LED via a resistor between PURPLE (+5VSB, pin 9: stand by) and BLACK (GND, pin 7 or pin17)
  • Wikipedia: ATX Power supply describes
    • PWR_OK (often called Power Good)
    • +5VSB (stand by)
  • read the specs of your power supply to understand how much current it can deliver on which lines
  • some more current information

Example for loads: https://www.youtube.com/watch?v=gKgziA46wFY; more on why you need them and how to choose:

With a few more modifications you can [WayBack] Convert a Computer Power Supply to a Variable Bench Top Lab Power Supply.

I will probably go for this solution as it is easier to swap power supplies.

–jeroen

Via: [WayBack] Nice recycling of an old ATX power supply with a 3D printed part and a few accessories and cables… – Jean-Luc Aufranc – Google+

 

[WayBack] Using PC power supplies in things other than PCs

Via: [WayBack] What is the power specification for SATA?

Details:

PC Power Connectors

 

How to Convert ATX PSU (PC power supply unit) into a cheap bench top power supply which can be used to power many different types of electronics circuits

20 pin molex connections

Pin Name Colour Description
1 3.3V Orange +3.3 VDC
2 3.3V Orange +3.3 VDC
3 COMMON Black Ground
4 5V Red +5 VDC
5 COMMON Black Ground
6 5V Red +5 VDC
7 COMMON Black Ground
8 Pwr_Ok Grey Power Ok (+5 VDC when power is Ok)
9 +5VSB Purple +5 VDC Standby Voltage
10 12V Yellow +12 VDC
11 3.3V Orange +3.3 VDC
12 -12V Blue -12 VDC
13 COMMON Black Ground
14 Pwr_ON Green Power Supply On (active low)
15 COMMON Black Ground
16 COMMON Black Ground
17 COMMON Black Ground
18 -5V White -5 VDC
19 5V Red +5 VDC
20 5V Red +5 VDC

24-pin molex connections

Pin Name Colour Description
1 3.3V Orange +3.3 VDC
2 3.3V Orange +3.3 VDC
3 COM Black Ground
4 5V Red +5 VDC
5 COM Black Ground
6 5V Red +5 VDC
7 COM Black Ground
8 Pwr_Ok Grey Power Ok (+5 VDC when power is Ok)
9 +5VSB Purple +5 VDC Standby Voltage
10 12V Yellow +12 VDC
11 12V Yellow +12 VDC
12 3.3V Orange +3.3 VDC
13 3.3V Orange +3.3 VDC
14 -12V Blue -12 VDC
15 COM Black Ground
16 Pwr_ON Green Power Supply On (active low)
17 COM Black Ground
18 COM Black Ground
19 COM Black Ground
20 -5V White -5 VDC
21 +5V Red +5 VDC
22 +5V Red +5 VDC
23 +5V Red +5 VDC
24 COM Black Ground

 

 

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