[sdiy] ARP Odyssey capacitors

[Nicholas Gregorich]

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
> 
> 
> 
> 
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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.