SET Asylum

Single Ended Triodes (SETs), the ultimate tube lovers dream.

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Re: Latest update

Posted by J Epstein on January 20, 2001 at 07:02:07:
Hmm. Wow, this must be frustrating. It sure is confusing.
Somehow your bias (on the 45) is screwed up. What you describe sounds like intermittent solder joints, now making contact, now open. And Doc B says that 90 percent of his kit builders' problems can be traced to that one problem.
So: re heat EVERY solder joint, starting with anything connected to the 45 socket or 45 filament transformer.
I'd especially be concerned about the 470K resistor from 45 grid to ground - if thise were intermittent I do believe it would cause the problems you describe.
As a double check, make sure you measure 470K ohms from that socket to ground with no tubes in.
Also verify the connections of the cathode bias resistors (1.5K from filament center tap to ground as you have it wired now.)
Finally, be sure all your electrolytic caps have teh (-) erminal to ground - these would be the 100uF cathode bypass caps on driver and 45. And be sure you are using a 100V rated cap on the 45 cathode bypass.
I'm just throwing a lot of stuff up against the wall. I hope some of it sticks!
-j