Electrolytic capacitors - a perspective

[laurie]

Over in this thread I talked about changing the filter capacitors in a 30 year old Peavey amp.
http://www.bossareaforum.com/Forum/view ... f=14&t=789

There are two schools of thought about this:

• Anything over about 20 years old, just replace the capacitors - if they haven't failed yet, it is imminent.

• Measure the capacitor and if it is within specification, leave it until it does actually fail (years in the future?).

In that other thread I said "I decided to change the main filter caps. 30 years is too old... whether I keep it or not, the caps are going to fail.".

But here is the conundrum. The readings for the capacitors I removed are below. They are still perfectly within specification.

So what is the right approach? In this amp the cost of the replacement caps was about USD$10.

So what I'm trading off is:

• $10 now when I have the amp open anyway.

• The risk/certainty of failure "in a couple of years" with the time to dismantle the amp plus the clean-up of the almost inevitable associated mess (leaked electrolyte).

That Peavey amp, made in the USA 30 years ago, likely had "good" components. So there are probably years (and years) of life left in the capacitors.

I had the amp open anyway. The cost was only $10. And I threw away components that tested as perfect.

If it was a tube amp and the capacitor replacement cost was $50-to-$100, I might have decided to leave them...
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[Pepe]

So what I'm trading off is:

• $10 now when I have the amp open anyway.

• The risk/certainty of failure "in a couple of years" with the time to dismantle the amp plus the clean-up of the almost inevitable associated mess (leaked electrolyte).

This is exactly why I do the same thing. I have the synth (or whatever) open anyway. The parts don't cost a fortune and they will ensure that it will work for the next 25 years or more.

I purchased good radial "Long Life" electrolytic capacitors from Panasonic for the '80s Roland Alpha Juno-2 synthesizer that I purchased lately. The three capacitors didn't even cost 5 EUR. They might prevent some headache in the future.