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

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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:

[WayBack] Convert an old ATX Power Supply into a Bench Power Supply with (or without) 3D Printed Parts.
[WayBack] Benchtop power supply with ATX connector

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
- [WayBack] Power spec for the PCI-E 8 pin power plug – [Solved] – Components
  - PCI-E 6 pin: Pins 1 & 3 are 12V & each can carry 8 A, totaling 12V*8A*2= 192W
  - PCI-E 8 pin: Pins 1,2,3 are 12V & each can carry 8 A (before ~ March 2005) or 11 A (after ~ March 2005), totaling 12V*8A*3=288 W or 12V*11A*3=396W
  - It also explains why not all pins in these connectors are connected or can carry current.
- Not just the connector, also the wires matter: American wire gauge: Tables of AWG wire sizes (and A rating)
- To get a feel read [WayBack] Using PC power supplies in things other than PCs and the pages he links to (see list further below)

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:

[WayBack] All about the various PC power supply cables and connectors (it has tables with the various part numbers including ones for parts of connectors and unofficial current/wattage that I’ve quoted below)
- [WayBack] oldpc: Original PC main power cables
- [WayBack] peripheral: 4 pin peripheral power cable
  5A per line; one 5V line; one 12V line
  (The connector is often called “Molex”, but actually is AMP Mate-N-Lok; Molex has tons of different connects, one of which is now compatible with the AMP one)
- [WayBack] floppy: Floppy drive power cable
  3A per line; one 5V line; one 12V line
- [WayBack]aux: 6 pin auxiliary power cable
  10A per line; two 3.3V lines; one 5V line
- [WayBack] sata: SATA power cable
  1.5A per line; three 3.3V lines; three 5V lines; three 12V lines
  (3.3V is often not connected)
- [WayBack] atxmain20: ATX 20 pin main power cable
  6A per line; three 3.3V lines; four 5V lines; one 12V line
- [WayBack] atxmain24: ATX 24 pin main power cable
  6A per line; four 3.3V lines; five 5V lines; two 12V lines
  (most PSU with the 24-pin connector omit the -5V lead from it)
- [WayBack] atxmain20plus4: ATX 20+4 pin main power cable
  6A per line; four 3.3V lines; five 5V lines; two 12V lines
- [WayBack] atx12v4: 4 pin ATX +12 volt power cable
  8A per line; two 12V lines
  (note it looks similar to the “plus 4” from the “20 plus 4”, but is different as the 12V4 has only 12V)
- [WayBack] eps8: 8 pin EPS +12 volt power cable
  7A per line; four 12V lines
- [WayBack] eps4plus4: 4+4 pin +12 volt power cable
  7A per line; four 12V lines
- [WayBack] pciexpress: 6 pin PCI Express power cable
  8A per line; two 12V lines (sometimes three 12V lines)
- [WayBack] pciexpress8:
  8A per line; three 12V lines
- [WayBack] pciexpress6plus2: 6+2 pin PCI Express power cable
  8A per line; three 12V lines

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

This entry was posted on 2018/11/16 at 12:00 and is filed under Development, Hardware Development. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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

Dominik Kwolczak said

2019/01/10 at 16:46
Seems very interesting!

Reply

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