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Yahoo!!! The Baby lives.
Heart palpitations when I fired her up with a 100 ohm series resistor in the B+ for a test. It promptly blew and I didn't know what to make of it. The Cap had voltage still on it, slowly draining, so it wasn't a dead short. I was a little perplexed. Decided to bite the bullet and buy a variac. Slowly winding it up, no smoke, no nasty noises.... 520 volts across the 500V cap... Oh Crap!!!!!
Hum out the speakers... ok, that's good ... sort of.
Warning for the unwary.. some variacs put out more than 100% at full tilt. Ok, back to 240V.
My caps now have 499 volts on them with the tubes drawing 63mA each.
Now I realised I had not fitted the 220K resistors to ground on the inputs. Hum (most of it) gone.
Hooked up trusty iPhone and Voila! lovely sound. Sounded weird though. Having read the full forum, I had to reverse the output transformer windings to get the feedback right. As it was, with feedback, more output which is wrong for negative feedback.
Now I have a small amount of hum to track down, but lovely clean sound.
I have to either get higher voltage first stage filter caps, or put in resistors to drop the voltage. (Damn Edcor for making such solid transformers!!!!)
Makes a lovely heater as it is winter here.
Thanks Bruce for creating yet another obsession.....
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