• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

st70 electrolytic caps

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hi

i had an st70 which blew out and so i modded it to include the curcio quad capacitor board, it still didnt work and the problem was eventually found to be a burnt power transformer. since then i obtained a another unmodified st70.

i am aware that electrolytics are unreliable and are recommended to be replaced; however the quad cap on this one measures well on a cap checker. furthermore i am very reluctant to mod the circuitry.

how long does it take an electrolytic to degrade (ie how often should it be rechecked)?

what i want is a physical drop in replacement for the can with better specs. if this is made, where is this available?

-gong
 
There are many things that come into play on how quick electrolytics degrade. Such as how close to there max Voltage they operate, how often the equipment is used, duration, manufacture, ect. I've worked on vintage equipment built 30 years ago where the caps were still doing their job. On the flip side I've worked on gear that was less than 5 years old where the caps needed to be replaced.

Usually in tube amps the signal caps are not electrolytics. So generally when you hear hum in the output or see excessive ripple in the supply, the electrolytics need to be replaced.
 
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