Darkvoice 336 - one channel dead and buzzing and low plate voltage - Page 2

I see. So a shorted half of the output tube might be giving us the difference in readings at the input tube.

Sometime next week (once I receive the tube I've ordered), I'll be sure to let you know what the result is of trying it in the amp.

As for the test you've suggested, I'm not entirely clear about how to perform it or what the reading ought to be if the tube is good, and what it ought to read if the tube is bad. That is:

(1) with regard to 'apply the test leads to the suspect plate' where ought the other lead be? Ground? 

(2) For a bad tube, what would be the sort of relationship between the initial voltage and the voltage as the tube begins to conduct? I figure the answer (though I'm not sure) is that the initial voltage will be high and as the tube begins to conduct then the short will pull the voltage down. Is that right?

(3) And for the good tube, I would figure that there wouldn't be much of a difference between the initial voltage and the voltage after the tube warms up. Is that the right way to understand the matter?

Problem solved.

Just received the cheap but working 6080 I ordered last week so that I can rule out the possibility of a bad output tube as the cause of the problem. Put it in, and voila, right channel working perfectly. So it looks like a bad half of the 6AS7 was pulling power from one side of the input tube, which would account for the much lower voltage reading I got there.

I want to sincerely thank you for your help and patience, digger945. It has been instructive for me to think about this matter with the help of your guidance. I have learned things.

All best,

cws5