Overview

New version

Updated v1.4.7 with improved support especially for older ATX power supplies. It is still, however, recommended to use more recent power supply.

Board

The -5V ATX Adapter board solves several issues when it comes to power supplies and AT motherboards.

The key issue is the fact that as power supplies age, they may become dangerous to both the user and more so to the old, often valuable hardware that those power supplies are used to power.

To solve this problem, two key issues need to be addressed.

First is the physical incompatibility between ATX and AT power supply’s output power connector; the 20 or 24 pin ATX power connector is physically incompatible with the older 12 pin P8/P9 power connector.

Second issue is that ATX standard has since removed the -5V power rail. This rail is required by some of the vintage hardware, especially some highly collectible SoundBlaster audio cards. And lack of this power supply rail prevents sound output from these cards, as the operational amplifier(s) used on these cards require negative voltage to operate correctly.

Both of these issues are addressed by The -5V ATX Adapter board.

In addition to the key issues, several other functionalities have been included.

First is the support for both ATX and AT style power switches. You can hence use an old AT case, or, alternatively, if case mounting or motherboard allows; install an AT motherboard into an ATX case and use the ATX power button. This would not be possible without such board.

And to make testing easier, the board includes an on-board button to easily turn the power on and off. This is particularly useful feature and if you do any work at the bench, it will become an indispensable feature.

LED are included on-board to quickly see the status of all the power rails.

Comes with backing plate for easy mount and to prevent short circuits. Use strong double sided tape to attach the board. Be careful if removing later, as the base will easily gave in if the tape is strong.

Compatible with both 24 and 20 pin ATX power supply connectors.

Adapter cable

This is a modified version of the commonly available ATX-AT adapter cable. The reason this cable exists is two-fold:

Firstly, the standard cable has too short leads to simultaneously connect the motherboard and the AT case power switch and hence, cannot be used for permanent installations into a case. This issue is solved with lengthening the power switch leads to 50 centimeters.

Secondly, the standard cable has 4.3mm connectors at the end of the power switch leads, while AT power switches normally use larger 6.3mm connectors, and as such, the cable cannot be used for permanent installations. This issue is solved by replacing the small 4.3mm connectors with larger 6.3mm connectors.

What is included

• Assembled and tested board
• Modified adapter cable