Replacing old eletrolytic caps even if correct value??

[Emetal]

Should I replace 25 years old electrolytic caps in an amp even if they are measuring correct capacitance and are not leaky, bulged or anything else?

[mhuss]

That depends. There's no need to replace functional components, but at 25 years they're definitely getting near the end of their useful life. If it's your amp and you plan to use it for a while, it wouldn't hurt to replace them 'while you've got it open.' If it's for a client and they'd have to pay for it, I'd ask them after explaining the situation.

I think of this akin to replacing old tires. There may be still a little tread left on them, but you know they're going to need replacing sooner than later.

[mozz]

That's only 1997. If the amp has been in almost constant use and there are no sound problems, leave them. If it has been sitting for years, yes change them out. I also go by brand. Cheap IC caps i hate and would change them. You didn't specify if its high voltage caps or solid state amp?

[Leo_Gnardo]

I think of this akin to replacing old tires. There may be still a little tread left on them, but you know they're going to need replacing sooner than later.

To some degree, that's so. I don't know about the rest of the world but in NY when I get annual inspection they give me grief if the tires are over 10 years old regardless of tread condition. "I can't pass these next year, old tires dry rot & you never know when one's gonna blow." Dry rot, sure it's a factor, and usually much worse in cheapo Chinese made tires what a surprise, less of a problem with the quality brands nonetheless still a factor. Your advice though is spot on: If the amp owner wants his prize to last another 25+ years get caps replaced now or soon. If on a threadbare budget like most musos, do nothing and take your chances but I recommend "bring a spare amp to gigs."

[Enzo]

Should I replace 25 years old electrolytic caps in an amp even if they are measuring correct capacitance and are not leaky, bulged or anything else?

When we discuss leaky caps, we don't usually mean all bulged and spewing fluids. Obviously caps that look that way are bad, but leakage refers to their ability to block DC voltages. And your meter cannot detect that. A cap that test fine at a few volts may leak like a screen door at a couple hundred volts. Value is rarely an issue.

I think it is more like a car battery. My Die Hard battery said "5 years" on it in big letters. At the end of five years would I throw it out and get a new one even though it has started the car in the dead of winter reliably its entire life?

[mozz]

4 vehicles, I replace car batteries every 5 years no matter what. You could have a dead cell so voltage would be low but still have lots of current. It would be trying to charge all the time. Newer cars you need to tell the computer you replaced the battery, so it goes into a different charging routine. Alternators aren't $35 anymore and are nowhere near as easy to change as they used to be. That all being said, the few i have seen die, were basically overnight and not even enough juice to open the door locks.

[nosaj]

I periodically put mine on a honda smart charger. To condition it and top it it off. It will desulfate the cells.
nosaj