Hi,
my bandmate has the amp in the subject that was motorboating, I found it was the last cap in the chain, changed with a 33uF/500v I had at hand and the amp was better than before as this guy pointed out, and I'm glad for him.
But I noticed, when testing voltages with a DMM, the voltage was going down to a few volts in a few seconds everytime the amp was in standby and this surprised me because I couldn't find on the schematic any bleeder resistor or a path for the caps to discharge and, in my ignorance, I suspect that maybe something else could be malfunctioning and eventually fail.
I'd like to have an explanation for this and opinions about it.
Thanks
HR Deluxe, where's the bleeder res?
Moderators: pompeiisneaks, Colossal
Re: HR Deluxe, where's the bleeder res?
Hot tubes will discharge caps pretty fast on many amps.
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Stevem
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Re: HR Deluxe, where's the bleeder res?
Any filters on the cold side of the standby switch will discharge thru the preamp section plate load resistors until the heaters die off enough!
In fact a great way to test the life that is left in a tube if you have a tube tester is to test at a lower heater voltage setting.
When I retube a amp I test the new ones at there normal heater voltage and 2 volts lower and a I record this test results in a file for that customers amp.
In fact a great way to test the life that is left in a tube if you have a tube tester is to test at a lower heater voltage setting.
When I retube a amp I test the new ones at there normal heater voltage and 2 volts lower and a I record this test results in a file for that customers amp.
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Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: HR Deluxe, where's the bleeder res?
Thanks.
So, if I understand correctly, until the heaters keep the cathodes warm enough, the tubes are still working at idle and the electrons find their way to ground from the caps through the cathodes when the standby switch is placed before any cap as in the hot rod deluxe where the switch is on the ac side of the rectifier bridge and there's not a lot of charge stored (47uF+22uF+22uF+22uF).
It seems it's doing pretty well because as I stated the voltage goes quite fast down to a few (about 10) volts.
So, if I understand correctly, until the heaters keep the cathodes warm enough, the tubes are still working at idle and the electrons find their way to ground from the caps through the cathodes when the standby switch is placed before any cap as in the hot rod deluxe where the switch is on the ac side of the rectifier bridge and there's not a lot of charge stored (47uF+22uF+22uF+22uF).
It seems it's doing pretty well because as I stated the voltage goes quite fast down to a few (about 10) volts.