[sdiy] Multi-section cap in old tube gear

[Roy J. Tellason]

On Tuesday 17 February 2009 10:21:08 am rdrake wrote:
> a friend of mine picked up a WOBBULATOR (lucky schmuck:
> http://electro-music.com/forum/post-209234.html).  there's a lot of hum and
> he's suspecting a multisection cap marked as follows:
>
> sprauge
> 40-450 dc
> 30-450 (square symbol)
> 10-450 (triangle symbol)
> 20-25
> can com. neg
> d13771              125
>
> i don't have a lot ov experience w/ tubes, but my understanding is that the
> terminals should have some symbols next to 'em to help key out which is
> which value?  but he's not finding the symbols.  

I'm assuming here that you're talking about one of those "can" type caps.  If 
you look at the bottom of the can,  right where the terminals come through 
the bakelite,  the symbols will be there,  as cuts into the bakelite and 
adjacent to the terminal.  Shining a strong light in there and possibly 
moving wires out of the way will make this apparent.

> any advice on what to try next?  i'm thinking the uf values may not be
> critical, and he could maybe just average the difference and use 30uf for
> all 4 and see how it goes... 

Nope.  I'd go with the values given as a minimum.

Here's the deal,  though.  Those terminals usually being pretty good-sized,  
they're often used as common tie-points for a *lot* of wires.  You're going 
to need to find someplace else to connect all of those wires and also all of 
the replacement caps.  Do NOT try to use the terminals of the original cap as 
tie points,  it needs to be completely disconnected when the replacements are 
put in there.  It can stay,  for cosmetic reasons,  or it can be removed,  if 
you want,  either way that doesn't matter much.

But yeah,  those symbols _will_ be there.

-- 
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-
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