Safety of Older Electronics

One thing that can fail are electrolytic caps.

Have them repleced and all should be good. It will probably sound better afterwards.

You might find the odd high power resistor fails also.

Every thing else should be fine.

A good tech should be able to assist for a reasonable price.

Regards.

Vintage solid state electronics that haven't been shelved
or garaged, used regularly will last longer than ones
unused. Transistor life is endless it spans up to 60,000
hours if USED regularly which is approximately a lifetime
or longer. As to DC filter caps is basically same. They
go bad if not used.

Yes, filter caps go bad when gear is not used for a very long time because electrolyte "eats" out aluminium oxide, a dielectric, reducing breakdown voltage (presence of voltage slowly rebuilds it), but filter caps can also go bad because they simply dry out. Current heats up dry capacitor because of its increased ESR causing further increase of ESR with temperature, resulting in avalanche effect and explosion of the capacitor. Because of that electrolytic caps have either fuse (rubber plug) or weakened top (groves). In room temperature capacitor will last 40-50 years but every 10degC temperature increase cuts its life by two. Capacitors placed in hot areas, for instance close to tubes, won't last very long.

Replaced that relay in the SX 737. All went well and no more banging sounds just nice clicks. And it sounds better too.

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?