STATUS: Done! (Nov 14, 2015). Pretty easy mod. Now I can sleep at night – electrolytics dry out, and the tantalums in the power supply felt like an accident waiting to happen.
Replacing old capacitors is something people do with old synths, mixers, amps etc. Some people swear by it, other say it is often a lot of mumbo jumbo, especially if the claim is that the audio quality got much better.
Anyway. It seems most techs agree on the following:
– Electrolytic capacitors are the most sensitive to aging (they dry out). And my Pro-One is 32 years old after all.
– Tantalum capacitors are bad in power supplies since they tend to ‘short’ when/if they fail. (The Pro-One has this).
So I’m gonna replace:
Desoldering & Replacing
I replaced the caps from the power supply first.
I then started up the Pro-One to see that everything still worked. It did 🙂
Next up: One capacitor that is connected to the ‘Reset’ pin of the CPU.
I thought the schematics said “10 uF” but the capacitor I removed read “1 uF”. Hmm. I read up on this and the capacitor is there to give a long enough pulse when the CPU is reset. This ‘resetting’ doesn’t seem to be something that is actually done, there is just a constant voltage connected to this pin. So I figured a 10 uF might work just as well as a 1 uF one.. Soldered it in, started it – all good. Fingers crossed.
Finally: The capacitors in the audio path.
These were originally ‘axial’ but I could only find ‘radial’ ones. Added some shrink tubing for insulation. They are also ‘audio grade’, whatever that means – can’t hurt 🙂
Final test – everything still works! (Nov 14, 2015)