[time-nuts] Replacing electrolytics - any disadvantages of high temp ones?

[Dr. David Kirkby]

I'm sure many of you with old equipment must have considered the fact that 
electrolytic caps have a finite life and considered replacing them. I have a few 
that look suspect (bulging) on a transceiver, and decided to replace them. I'm 
tempted to do all of them in the PSU, as:

* It runs hot
* PSU could destory other bits
* Two of the 15 or so caps on the PSU board show signs of bulging.

For the PSU I used all 105 deg C caps, apart from one which was rated at 125 deg 
C. These are higher spec than the originals.

I also replaced another cap (not in a hot region) with a 105 deg C rated cap.

I've made my capacitor choice based on assuming.

1) Higher temperature devices (like 105 deg C) will be more relieable than low 
temperature ones like the standard 85 deg C cap. I'm sure at high temperatures, 
that must be true, but I've no idea if it would be beneficial if the cap does 
not get very warm.

2) There are no disadvantage of the higher temperature caps, other than cost.

Are these true?

I've ruled out the idea of replacing all electrolytics with new ones. That would 
be a LOT of work, and cost a lot of money.

Dave


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