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Re: Excess line voltage can kill an amp

Posted by koo on November 4, 2003 at 17:34:29:
Thanks, I have no other instruments to check, basically use a quality digital meter to measure the household voltage, since this is very cheap nowadays, at around US 80. Whether an analogue would read less 5V or 5V more, it is not important, afterall, it's inaccurate(2.5% accuracy) Very few people would use exceptionally high quality analogue meter from AVO for domestic use.
I think the life of electrolytic cap would be doubled for 10C less, assuming that it behaves like a battery,maybe drying out of electrolyte would severely affect its life too. I have a cap that bothered a bit, rating 30V, 2x1000 uF, with slightly higher ESR than others, 0.7 ohm against 0.4 ohm(new stock is 0.2ohm) the voltage output seemed to be normal 29V dropped to 23V supplying four small tubes in series.It's a bit warm, should say warmer than the transformer.
Solen cap is polyproprene, I think it's self healing. There is 600V 20 uF Sprague axial electrolytic cap(from Angela and Triad electronics) and I may use them in my Dynaco III just ordered, the website suggested the use of 550V cap for this equipment, plate voltage 485V. Maybe, I would use 5U4 to drop the B+voltage a bit thought the filament current would be 3A.
People had suggested the unplugging of power tube from vintage equipment for testing so this is a mal-practice. Should unplug and use variac to reduce the line and B+ voltage to avoid cap explosion.