The Shop > Electronics & IC Programing
Siemens micromaster 420
seadog:
I remember a large paper electrolytic going bang one day, 600v rail for a transmitter. It filled the workshop with smoke and the smell hung around for days. Open frame too since I didn't have a case to fit it into. It certainly gave my heart a good work-out :bugeye:
The can left left a nice mark on the ceiling too.
But I digress.
I believe the correct way to reform capacitors is to apply the full rated voltage but to limit current via a series resistor. In a perfect world you'd have a variable PSU with current limiting so that current could be increased incrementally.
appletree:
Thanks for all the helpful replies, what you all have said follows what I was thinking, I was purposely vague as to entice considered answers. Before i retired I was an instrumentation technician, so had more than half an idea. Just didn’t like partial powering up of the clever electronics, but as philf has said its their procedure so should be fine. Will let you know how i get on will do it outside in case we end up "tuning for maximum smoke” if it ever stops raining.
Thanks again Phil
Bluechip:
If anyone's interested I designed and built a cap. reformer some years ago.
Does most working voltages from 16V to 100V, current limited @ 10 mA.
If anyone wants I'll rake out the schematic. I think I still have it somewhere.
Dave
awemawson:
When I did the ones on my Chipturn CNC lathe a few years back (as it had stood idle for 3 years before I got it) I just rigged up a lab supply, set to the rail voltage of the capacitors, but with the current limit wound down to a few milliamps. That way you could observe the voltage slowly increasing, and if it plateaued before it got to the rail value you knew there was an issue with breakdown.
appletree:
Thanks for the further comments,
Dave I imagine your circuit will be for capacitors sat on the bench as opposed to in circuit? I don’t intend removing mine.
The manual says to start at 25% supply for 1 hr so I shall start lower than that maybe 5 or 10 volts using my variac.
Does that seem like a plan?
Phil
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