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Author Topic: Rejuvenating Dormant Filter Capasitors  (Read 16947 times)
W1BR
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Posts: 4196




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« Reply #15 on: July 05, 2016, 07:52:47 PM »

A lot depends on the quality of the caps.  I have many 60 year old Sprague can capacitors that will reform to under 100 uA leakage current within several seconds. I also have some Aerovox caps that take hours to reform under 1 mA leakage.  30 days later, they are useless and need reforming.  These are NOS caps.  If caps require any appreciable "recycling"  I would NOT trust them.  On the other hand, I have a lot test equipment made by HP,  and it is rare to find a power supply cap that needs reforming, or one that has developed a high ESR after decades of operation or storage.

Pete
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N8FVJ
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Posts: 910




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« Reply #16 on: July 06, 2016, 08:45:23 AM »

I buy new, not new old stock. NOS wares out on the shelf. I will not risk a transformer for a $10 (JJ) can cap to $38 can cap (Antique Electronic Supply). Heyseed is also a supplier.
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AA4HA
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Posts: 2630




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« Reply #17 on: July 09, 2016, 07:43:20 AM »

It might not be a bad idea to add in a B+ fuse at the transformer in case you get a cap that goes completely kilter and turns in to a load resistor. Some boat-anchors have B+ caps, other models (like the R-390A) had them added in the manufacturing cycle with retrofit instructions for radios already deployed.

Fortunately on receivers the B+ current is very low. The fusing I have seen was at 1/8 of an amp.
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
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