[AMPS] Re: Filter Capacitors

[Rich Measures]

>Old electrolytic capacitors need to be *formed* by applying
>HV in steps, ramping up across 12-24 hours.
the time can be under an hour or several, depending on age, who made it, 
and service history.  The critical thing is to limit current during the 
reforming process.  
>If they end up taking full rated HV without going out of spec,
>then they are ready to go back into service. 
the critical thing seems to be meeting the leakage spec. at the rated wV, 
at the rated temperature. 
>The practical way is to put them is strings of 4 or 6 across
>the supply.  When the HV is stepped up to full value, measure
>the voltage aappearing on each capacitor.
safer to measure the leakage I in each C during the process.  
>Eg: if there are 6 across 2400v, expect 400v +/- 10% across each unit.
>Excessive voltage on one capacitor indicates it is *dry* and 
>should be discarded.
might be better to measure the C of each beforehand, and/or look for 
white deposits around vents.  White deposit or low C means trash-time.  


cheers
Rich...

R. L. Measures, 805-386-3734, AG6K   


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