Thank you, Gadget. I was beginning to think I had asked a
verboten question.
Well...I have good news and bad news.
Good news: The IBAM board is hooked up, as are the 10 ohm resistors.
Probably while Gadget was composing his last reply to my question, I was searching this site via Google for answers.
I found
this warning in another thread, so after performing the test called for in that thread, I put the original weak Fisher 7189 tubes in place, and set the Variac to 110 volts.
Bad news: My IBAM doesn't work.
The voltage across every 10 ohm resistor is fluctuating between 57 and 65 mV. And the trimpots have no effect. The sound is now distorted (probably, I suppose, because of the bias now being wacky?). Damn the luck.
I shall have to set this aside for awhile, and will return to it sometime next month. In the meantime, I would certainly appreciate any comments, suggestions, etc.
Edit: Forgot to mention...last night I cleaned the socket contacts of the V20 (7199) tube socket with DeoxIT and one of those tiny brushes meant to use between one's teeth. The left channel seems to be OK now (no longer suddenly popping in after a few seconds' delay).