From: cd@notformail.com   
      
   On Mon, 4 Mar 2024 09:40:20 +0000, liz@poppyrecords.invalid.invalid   
   (Liz Tuddenham) wrote:   
      
   >Cursitor Doom  wrote:   
   >   
   >[...]CD.   
   >>   
   >> PS: the aforementioned caps are 47000uF 16V Vishay ones - and I have a   
   >> brand new spare that's also testing as "leaky"!   
   >   
   >If an electrolytic capacitor hasn't been used for some time, it is a   
   >good idea to charge it up from a variable-voltage power supply, starting   
   >at a very low voltage with an ammeter in series.  If it is leaky the   
   >initial charging current surge will settle down to a steady leakage   
   >which will decrease in time.  Then the voltage can be raised a bit and   
   >the leakage current will increase for a while, then reduce again.   
   >   
   >By doing this slowly over several hours you re-form the insulating layer   
   >in the capacitor.  If you apply the full voltage straight away, the   
   >leakage current will be high and can cause further damage.  It can also   
   >boil the electrolyte and cause the capacitor to explode.  Modern   
   >capacitors have a 'safe' explosion arrangment built-in (a pattern of   
   >weak points in the top of the casing) but older ones don't - and the   
   >damage from flying debris can be quite spectacular (I have seen a CRT   
   >cut in half when a capacitor can went through it).   
      
   Quite so. I blew up a little 10uF 10V cap the other day and the bang   
   wasn't far off that of a starting pistol. Mind you I did use a massive   
   over-voltage reverse polarity to purposely get a bigger bang out of   
   it. I don't often get bored, but that's what happens once in a while.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)