Aphex sold a lot of these 200/230/Channel Mike Processors. Unfortunately the built in power supply doesn’t age well.
They have a somewhat unique sound thanks to what they call “reflected plate”tube technology. The tube is run at a very low voltage with very small changes in plate current “reflected” onto solid state amplifier circuitry.
The original power supply is a fairly simple “flyback” type switching supply. Unfortunately it’s run at nearly 100% capacity and tends to fail catastrophically. Aphex used to sell replacements, but discontinued doing so after being sold to Rode.
The Fix I prefer is to remove the OEM power supply and integrate an external Meanwell “Brick” PSU. A DIN socket is added to the back for a direct connection. The unit I use runs at 50% capacity and should last the life of the processor. It supplies +/- 15V and +5V, so we will need to generate the +48V supply by other means. First attempt to do that used the open frame upconverter pictured below. Unfortunately the noise it emitted got into the mike preamp circuit and was audiable in the background.
The second attempt used these 12V to 48V Upconverters. They accept 12-18V and generate 48V at 1 amp output, many times the required current. These units run quietly without any electrical noise to get into the amplifier.
Total repair costs roughly $100 in parts and should last much longer than the OEM supplies.