In Reply to: RE: Extend tube life options.. posted by Paul Joppa on November 24, 2015 at 13:41:19:
I've inserted a hefty over-rated switch between the B+ output of a power transformer and the rectifiers, in order to allow tube filaments to warm up before applying B+ to the input stage of a PP amplifier. Thus the switch sees AC (about 400V), not DC. In one of two monoblocks, I have had a catastrophic failure of the switch, whereas the switch in the other monoblock is doing fine after at least 6-7 years. I had attributed the switch failure to faulty or poor quality construction of the switch, but should I reconsider this method of switching B+ altogether? In other words, is AC voltage as bad as DC voltage for damaging or stressing a switch?
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Follow Ups
- "Note that hot-switching high DC voltage damages switches quickly" - Lew 08:12:14 12/01/15 (0)