life span/failure rate of filter capacitors?

Eric has provided good advice. Plus you may also begin to hear fluctuations in the music with power capacitors. If you are in the NYC area I can take a look at your unit. On Parts Connexion look for Nichicon Super Through parts. You can go up in value if you have to just make sure that they fit in the space you unit has.

Thanks, @bigkidz , I just did a search at PartsConnexion for Nichicon Super Through Electrolytic caps, and surprisingly they came up then when they had not came up before. However, not the value that I believe are in there presently (560uf 400v).

As far as @erik_squires ’ advice, this amp is a 2001 model, and I did have the bottom off two years ago to change the signal caps and at the time I was looking at and checking the values of everything I could (because it was a biasing issue that I was trying to fix) and those large filter caps appeared good from a totally visual perspective, and I remember that with a cheap Chinese capacitor checker from Amazon, they tested within parameters.

It was just that thread I pasted above that got my ruminating on this. And I am curious about this: I took this amp out of service in 2010 and didn’t put it back in action until quite late in 2017. (And for a couple of years prior to 2010 I barely, if ever, used it.) Should I look at these caps as 21 year old filter caps, or as 14 year old caps?

I am in Pa., in the Pitt area, btw.

Thanks.

It's  a lottery, but 20 years is good going. That said, I have a pair of Meridian active speakers in my garage that are still working 35 years on. It kind of depends on whether you believe in preventative maintenance or are a kind of fix it when it breaks person.

Each 10degC temp increase shortens capacitor life by 2.  It is simply drying out of electrolyte.  Drier capacitors have higher ESR.  At certain point current thru capacitors causes internal temperature increase.  Temperature increases ESR and higher ESR increases power dissipated inside increasing temperature further.  It is Avalanche effect that can cause explosion.  To prevent serious damage all electrolytic caps have some form of pressure relief - either rubber plug or cross cut that weakens one side.  Hot capacitors should be replaced as soon as possible.

@audioman58 

caps get dried out as they age .

and does that statement apply to caps in units that have sat unused for a number of years?  My amp didn't see much (if any) use from '08 through '10. and in '10 I officially unplugged it and it was dormant until nearly the end of 2017.

@yoyoyaya 

It kind of depends on whether you believe in preventative maintenance or are a kind of fix it when it breaks person.

I generally like to fix stuff before it breaks.  Particularly stuff that might cause a lot of damage when it breaks.