From: whit3rd@gmail.com   
      
   On Monday, August 28, 2023 at 10:15:50 AM UTC-7, ohg...@gmail.com wrote:   
   > On Monday, August 28, 2023 at 7:29:09 AM UTC-4, Dan Green wrote:   
   > > Hi all,    
   > >    
   > > Is this okay? I'm talking about replacing electros that have been in    
   > > service for like 30+ years and which have a rep for failing by then    
   > > (Frako caps) with old but unused electrolytics; so called "new old    
   > > stock" caps of reputable manufacturers of the same spec. I can't see    
   > > an issue with this but am no expert so.... what d'yall think?    
   > >    
   > > Dan.   
   > Years ago, I tossed out my NOS electros because testing them was uncovering   
   some leakage at voltage. I don't recall the brand names if you're wondering   
   that but brand new quality caps are so cheap that it didn't make sense for me   
   to use the old ones.    
      
   It's a transient leakage, probably.   The manufacturer poles the electrolytics   
   by deliberately feeding leakage   
   current, to drive the chemistry to form the oxide layer, which... doesn't leak.   
      
   After storage for months to years, the oxide layer can thin or perforate, but   
   biasing it up (and leaving it   
   at voltage for a few minutes to hours) rebuilds the oxide.   NOS items don't   
   meet like-new specs   
   straight off the shelf, but usually DO work normally, by day two under bias.     
   I've also used a   
   curve tracer to watch the leakage, and applied hot air to speed it up, and   
   re-formed electrolytics   
   back to good-as-new while watching the leakage current dwindle.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)