The LaST Upgrade Part 50 - Atari ST DIY PSU

Last updated April 11, 2024


This DIY PSU uses 2 MW PSU blocks which can operate on 100VAC to 240VAC making it suitable for worldwide usage. This power supply is aimed as a low-cost DIY solution, to replace the failing original power supplies.

The PCB holds a ripple filter to considerably improved noise and ripple output of the modules. Typically around 30mV p-p with MPM modules. The PCB also holds additional mains noise filtering to help protect the modules. The PCB is designed to limit the exposure of live components on the top side of the PCB.



The PCB comes as shown above with fuse and holder (may not be not fitted).

At the time of typing, the assembled image was the initial prototype V.01 which was not commercially sold. The second version as shown above, V0.2, is currently sold in the store. There may be other revisions in the future, but they will likely to be anything more than minor changes.



PSU CONNECTOR: 30mm, 45mm, Falcon
5V PSU BRICK: MPM-20-5 or IRM-20-5 & MPM-20-12 or IRM-20-12

PSU SWITCH (if required): Original Atari

You will also need your old PSU frame. Ideally should be from a SR98 PSU. Other frames could be used but may require some wires lengthening to fit.



MPN DATASHEET - IRM DATASHEET (may not be current versions)

In a nutshell, the MPM is a medical grade power supply offering better regulation, protection properties and efficiency. The IRM modules are lower cost but also have slightly worse specifications. But please note, that they are not going to be worse than the original Atari power supplies eitherway.

Please note that while the MPM modules were tested, because of the additional output filtering on the PCB, the rippling noise levels are now approximately 30mV. IRM modules were not tested.