Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: catnine on July 04, 2011, 04:57:04 pm
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I posted I was actually reading mV and not Volts . I lifted the end of the .02 uf coupling cap to check for DC and found perhaps 25 Mv DC . My question is with this cap out of the circuit and the 220k ohm resister still connected to the 6V6 pin 5 to ground. I left the cap out for a while checking, maybe an hour at idle nothing plugged in , does this harm anything ? I heard a clink noise like a tube expanding yet reconnected the .02uf cap and the amp seems fine. This would be pin 6 of the 12ax7 with plate voltage on it and no signal going to the grid on the 6V6 .
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I lifted the end of the .02 uf coupling cap to check for DC and found perhaps 25 Mv DC .
If you're checking leakage by this method, you're reading voltage drop across the meter's input impedance.
Let's assume you used a digital meter with a 10M input impedance (yours might actually be lower, but probably not higher, unless you're using a high quality VTVM). 25mV / 10M = 2.5nA leakage. That's plenty fine. Another way to look at that is it represents 2.5mV shift of bias across a 1M input resistor (and only 0.55mV across 220k). That's negligible in your circuit.
I left the cap out for a while checking, maybe an hour at idle nothing plugged in , does this harm anything ?
Nope.