Buy ATX4VC | Discord | User Manual | Table of Contents

ATX4VC lets you use ATX power supply on vintage computers.

It has:

• All common voltages: +12V, +5V, +3.3V, -5V, -12V.

• Power button and power LED headers

• PWM fan headers with temperature probe support

• Addressable RGB(ARGB) headers

• USB-C power output and firmware update

ATX4VC can be used to:

• Replace retro computer power supplies

• Add cooling and lighting upgrades

• Test and diagnose vintage hardware

• As general-purpose multi-voltage bench PSU

Click me to get one on Tindie!

In my RGBeeb project, ATX4VC (seen lower right) powers a BBC Micro with +5 and -5V using a full-size ATX PSU.

But of course, a pico ATX PSU makes more sense due to its compact size.

Here it replaces the failed PSU in my Osborne 1, providing +12 and +5V.

I even took it to a coffee shop and wrote most of this very document! But that's for another day.

You can also use it as a multi-voltage bench PSU for testing and diagnostics.

Here it powers a Macintosh Plus motherboard with +12, +5, and -12V.

Power supplies are a major failure point of old computers today. Those early PSUs are heavy, inefficient, hot, and (slightly) explosive! After 40 odd years, many are not working, or worse might cause damage with out-of-spec voltages.

ATX4VC is designed to replace them with much more reliable modern ATX PSUs, and help test and diagnose vintage computers.

Quick Start Guide

Power Button and Power LED

Power Connection

Current Limit

Fuses

Fan Headers

Temperature Probe

Addressable RGB (ARGB)

USB-C Power Output

Dimension Drawings

Hard Power

RGBA over USB

Additional Headers

USB Firmware Update

• Make sure the jumper is in "soft power" setting (right two pins)

• Plug in ATX connector

• Press the power button

The PSU should turn on, all voltage rail LEDs should light up.

That's the gist of it! But please do keep reading for the complete info.

You can use the built-in power button, or connect an external button to the header.

You can also add an external power LED. Be ware of polarity. No need for external resistors. A 2.5K resistor is built-in.

Observe the voltage on each terminal block.

• Strip the cable

• Loosen screw

• Insert into hole

• hold the terminal block steady with your finger while tightening it back up

• Don't leave conductor exposed to prevent shorts.

Also, make sure the conductor is thick enough!

Alligator clips are handy, but many have very thin wires. If so, you can solder a thicker cable to it.

Label the rails, vinyl stickers are available in the product page:

Before powering up:

• Double check the correct voltage terminal is used

• Check for dead shorts between each voltage rail and GND, and between themselves!

Once powered up:

• Check voltage readings on each rail

Remember that ATX4VC DOES NOT monitor or condition PSU voltage outputs, so make sure the PSU itself is of good quality and trustworthy!

ATX4VC has current limit as follows:

• 5 AMPS MAX OVER ANY SINGLE RAIL

• 7 AMPS MAX TOTAL CURRENT OVER ALL RAILS

If more is needed, tap the power directly from a Molex connector.

See your PSU label or datasheet to see how much current it can provide:

+12V, +5V, and +3.3V are fused.

• USE FUSES RATED 5A OR LESS

• DO NOT BYPASS FUSES

ATX4VC uses common car fuses. Regular, Mini, and low-profile Mini all will work. Simply push into the holder.

Negative rails are not fused because they are low-current (around 200mA), and built-in protection is adequate.

Two PWM Fan headers are available. You can plug in standard 12V PC fans, both 3-Pin and 4-Pin.

Press FAN SPD button to cycle through different speeds:

Speed control only available on 4-Pin fans. 3-Pin fan will always run at full speed.

ATX4VC supports the DS18B20 temperature sensor. They are inexpensive and very popular in Arduino projects.

The cheap ones on ebay are almost certainly counterfeits! They'll still work, but readings are noisier and less accurate.

Try a reputable distributor like Sparkfun, Adafruit, Mouser, or Digikey.

Connect the headers. Usually VCC is red, GND is black, DATA is yellow.

Press FAN SPD button until the user LED slowly blinks 5 times. Now fan speed will depend on the temperature reading.

The fan starts to speed up at 25°C, and reaches full speed at 50°C. If probe is not detected, it will run at full speed.

You can use a heat gun and air duster to test out the probe.

Two standard ARGB headers are available. Simply plug them in. Up to 100 ARGB LEDs are supported.

Use RGB MODE button to change animation type, BRIGHT and COLOUR button to adjust brightness and colour.

Hold the button to cycle through faster.

Two USB-C connectors are available for powering external devices.

The left port provides 5V Standby, which is active even when PSU is off. Although max current is limited (typically 1 to 2 Amps)

The right port is on regular 5V rail. It can provide more current, but only available when PSU is on.

Those ports are output only, don't try to backfeed them with another powered device.

ATX4VC is compatible with 2.5 inch PC drive bay, and is compact enough to fit in most vintage computers.

Use M3 screws and nuts. Dimension drawing below:

Move the jumper to the left for hard power.

This shorts PS_ON pin to GND, and turns on PSU immediately when plugged in.

You can use the rightmost USB-C port to carry ARGB power and signal in one cable.

Short the jumper with some solder to put ARGB data on the D+ line. Seen in RGBeeb.

External momentary buttons can be connected to adjust various settings:

A few more signals are available on headers.

TURN OFF AND UNPLUG ATX PSU BEFORE STARTING.

Under construction ...

Quick Start Guide

Power Button and Power LED

Power Connection

Current Limit

Fuses

Fan Headers

Temperature Probe

Addressable RGB (ARGB)

USB-C Power Output

Dimension Drawings

Hard Power

RGBA over USB

Additional Headers

USB Firmware Update

Feel free to ask in official Discord Chatroom, raise a Github issue, or email dekunukem gmail.com!