Capacitor reforming

I did get the TR-20 completely dismantled. If they sit around for decades, electrolytic capacitors lose their internal insulating oxide. If you just plug them in, they will internally short, get hot, and potentially explode (not a big bang, but very messy).

But, they can often be recovered using a process called reforming. You apply voltage at the capacitor rating through a current limiting resistor for many hours and the oxide reforms. The picture shows the setup with lots of jumper leads. I'm reforming the 4 big 2500uF electrolytic capacitors in the power supply. I experimented with one and it was working well, so I set them all up and they are sitting there. They all appear to be recovering well. I will reform them for about 6 hours this way, watching the voltage carefully. There's some smaller caps on the power supply board, but I'll get these first. Those may be easier to just replace.

I want to get the power supply completely working first. Then I'll start moving in modules one at a time, starting with the reference supply, which uses the same precision amplifiers as the rest of the machine.