This Ace Tone Rhythm Ace FR-1 Analog Drum Machine came in with hum in the audio signal. Customer told me he already re-caped the psu, but still got hum.
While re-capping often is not a bad idea in these old machines, especially re-capping the psu, this does not always fix the problem(s).
This Ace Tone here was heavily case modded. It was not in the original, but a smaller housing. Therefore the transformer was moved from it`s original place. And that was causing the problem. The transformer was placed way to close to the voicing board, so that the magnetic field of the transformer influenced (still lokking for a better translation) the voice coils on the voicing board.
Placing the transformer in a different spot let the hum go away.
There are lethal voltage exposed in electronic devices. Unless you know what you are doing, don’t try this. If you following along, you doing so at your own risk.
I’m documenting repairs for my reference and yours.
I do synth restorations and repair with a specialty in vintage synthesizers, drum machines and other vintage gear, based in Düsseldorf, GER. Get in touch about your synth situation!