[sdiy] ARP Odyssey capacitors

[Roy J. Tellason]

On Monday 23 July 2007 21:18, Nicholas Gregorich wrote:
> Paul Perry wrote:
> > My own feelings about replacing caps in old synths:
> >
> > There are two reasons for replacing or substituting a component:
> >
> > 1. if you think the component is faulty, or likely to become so,
> > 2. if you believe replacement will for some reason actually "improve" the
> > design.
> >
> > In my experience, polyester or polypropylene or ceramic caps rarely fail.
> > So they stay there unless there is obviously something wrong & it looks
> > as though one is the problem.
> >
> > Electrolytics can dry out & lose capacitance over the years.
> > I don't automatically replace electrolytic bypass caps as a general rule.
> > If the main power filter caps are drying out, you will know something has
> > to be done, because of the hum.
> >
> > Tantalums are a special case.
> > Their design & manufacture has improved enormously over the years.
> > Early ones had a regrettably high failure rate. And they don't like
> > overvoltage at all.
> > So if one fails, then that's an argument to replace all.
> > (same as for those dodgy self-dissolving electrolytics from a few years
> > ago, but I havn't seen them in synths, only audiovisual gear).
> >
> > As for caps going leaky - they aren't usually under much stress in a
> > synth & it doesn't happen a lot. It's likelier to be crud on the PCB
> > surface itself.
> >
> > Really, unless there is an actual problem, it comes down to personal
> > preferences. I'm very conservative & like to leave stuff alone; others
> > are more high energy & if they think they can replace stuff without
> > buggering anything else up while they are doing it, then they can go for
> > it, I guess.
> >
> > Paul perry Melbourne Australia
>
> I am finding it a difficult decision. I see the advantages/disadvantages
> of both leaving the caps alone and doing preventative maintenance. I may
> compromise on just rebuilding the power supply and replacing any caps
> that I have tuning issues with. Initially I was planning to tune the
> synth after recapping, but I think my plans have changed.
>
> Nick.

Tuning?  I think you'll find that _very_ few components are actually involved 
in tuning,  overall...

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