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Old 3rd Aug 2020, 1:06 pm   #26
Techman
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Join Date: Nov 2009
Location: Lincolnshire, UK.
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Default Re: Dansette rectifier switch on surge

I should probably just clarify things a little regarding the above post.

The problem (if you can call it that) is the same, but the other way round (if you see what I mean).

In your case with a solid state rectifier, the voltage starts high and then drops to a level below the working voltage of the can capacitor when the output valve warms up and conducts to load the supply. However, in my case described with a valve rectifier, the voltage starts at zero and rises to a higher level than the working voltage of the can capacitor as the thermionic valve rectifier warm up and conducts, regardless of the fact that the output valve has also warmed up and is fully conducting and loading the circuit. So in your amplifier the overload to the capacitor is very short term, whereas in my amplifier it is continuous once the amplifier has warmed up and is working. I checked all current drains and transformer tappings on my amplifier and everything was normal, so that's just how it was designed - to be right on the limit!
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