Safety of Older Electronics

Sorry what do you mean?

I got it...I agree, I knew about the rule that it needs to be turned on, and do work, in periods - and not left stone cold. This is in tune with my own experience over the years - it is after longer periods of being off, that mid-age equipment is likely to fail. Having not being used for a longer period.

Yes. We have some of that in Scandinavia too, great outdoors where I live, big woods north of Oslo, I go there to charge my batteries, so to speak.

Yes I realize. It can be tested but a lot of work. My experience as a user is that the hotter the box, the greater the need for regular service. Although I have had some great exceptions too. The Krell FPB600 amp ran very hot, in periods, when I played loud music, over twelve years use, and never showed any sign of failure.

So, if it is difficult to make a general rule, service after five, ten or fifteen years, based on temperature in the chassis - perhaps a better way to go, is through the symptoms of aging equipment? What are the typical signs of caps and other parts that are no longer performing optimal?

Thanks, very useful. Other symptoms to look for?

Czarivey, I have experience with old amps that confirms the rule, dont leave them off for years, that you mentioned above. Like my Revox A78 amp. It always played decent in the 1970s, was left off for ten years after being replaced by a Yamaha amp in 1985, but when I brought it to a friend's cottage, to try out among other amps, fifteen years later, it just did not sound at all, the music was clearly wrong-sounding. So I had to pack it away, a bit embarassed. The Yamaha amp, on the other hand, having been used off and on for fifteen years, required service in the late 90s, but the loss of optimal sound was much more graceful, not catastrophic as in the Revox case.

Thanks for an interesting thread, also for a non-engineer.
Kijanki, the 10degC rule, what is the starting point, the “normal” temperature in the box? I have ca 20degC in my listening room, but the temperature inside the audio boxes varies from very hot esp tubed equipment, to medium hot to quite cold just a bit above 20degC. If the rule is true – hot-running boxes should be serviced quite often! Is there a typical failure time for electrolytic caps (Williewonka) for each given temperature in the box? Also, I did not know about the use factor, that it works positively over time (Czarivey).
Since the thread concerns how to minimize wear and tear and aging, it is of general interest, not just for vintage owners. I started a “total cost of ownership” thread some while ago here on Audiogon, check it up – this relates to the same theme.
So ideally, the user could check the temperature within the box, input yearly “on” time (or total use hours), and know when it is time for service, and what components should be replaced?