[sdiy] ARP Odyssey capacitors

[Roy J. Tellason]

On Sunday 22 July 2007 04:51, Bob Weigel wrote:
> I've not seen actual failure of an of the ceramic or silver mica caps.
> I mean...mica and other minerals obviously are pretty stable until it's
> punctured by HV.  The Orange drop caps are also pretty good long term in
> most cases being what polypropylene?

Mylar.

> That I'm aware only the tantalums tend to fail at about this age and
> possibly the other electrolytics in the PS could use changing.

Tantalums tend to fail only when pushed to close to their maximum voltage 
ratings or beyond them a bit.

> And also in many cases regular electrolytics are fine but some the lower
> esr is of advantage.  (In particular the classic ARP Omni deal where
> they used 22uF tantalums all the way across the release envelopes!  I
> mean...c'mon.  We're talking relatively slow response needs here as
> these caps charge and discharge to create the envelopes.  I don't
> believe anyone can tell a difference.    -Bob

The big problem with those 22uF tantalum caps in the Omni is the fact that 
they used 25V parts in there,  and it's in a circuit that can see as much as 
30V across the cap,  depending on the setting of the release slider...

No wonder there were failures!

> Nicholas Gregorich wrote:
> > Hello. I am recapping my ARP Odyssey. I have a couple questions.
> >
> > Should silver mica caps be replaced during a restoration? How about
> > film capacitors? For that matter should ceramic disc capacitors be
> > changed?
> >
> > I've read some advice to replace tantalum capacitors with electrolytic
> > when recapping. I don't think any have failed on the Odyssey but maybe
> > it would be better to get high voltage rated tantalums if available?
> > It doesn't seem like a great idea to replace a tantalum with an
> > electrolytic because of their higher ESR.
> >
> > Can anyone identify the orange capacitors in this photo:
> >
> > http://homepage.mac.com/nicksdsu/temp/board_b_caps.jpg
> >
> > Are they a type of film capacitor (n00b question I'm sure)? They
> > aren't listed on the ARP parts list (I found a few other errors on the
> > schematics/parts list). I just noticed these caps are on board C as well.
> >
> > Finally, is the best way to remove the filter module by desoldering
> > the filter pins from the main board or desoldering the filter PCB from
> > the filter pins?
> >
> > Thanks!
> >
> > Nick.
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