So I went on to debug my unit.
Btw, this is one of two units I'm building! I went to byte the bullet and build simultaneously two units. That's four channels! Hehe!
I've went to read a lot through this and similar threads. Too many success stories gives me confidence that this will work one day.
I've returned to serial connection of heater wires. At first when I had them in parallel my PSU had tendency to shut down since 10R/5W was getting real hot. Now when connected in a way Abe originally suggested, everything is ok.
But check this out - the boards I got for tube connectors don't have pins 4 and 5 routed! There is no connection from tube socket pin to the pin on the bottom of the board! These are the boards I got from Abe later, after he realized that original tube pcbs had error (they routed backwards) . I've traced other pins on this "new" pcb and rest of it is proper.
So I had to hardwire the heaters directly to socket pins 4&5 instead of connectors AB/BC!
Anyway - heaters are good. Tubes glow and work on appropriate heater voltage.
My first channel is dead. It doesn't pass audio.
Channel two is passing audio but it doesn't compress. And level is a bit low.
But for now, my main problem is oscillation. It's very hard to diagnose where the faults are since after turning on the unit it takes about minute or so before I get motorboating oscillations and I have to turn off the unit.
I'm trying to find out what's wrong. I'll keep working on it in next days.
Motorboating starts when needle on the meter reaches it's top value. Somewhere there.
Voltages seem okay - I'll have to measure them few more times.
HT sits on 103vdc and that's supposed to be okay.
Other rails are also good.
I'll keep you posted in my debugging work.
If someone has constructive ideas please do post them!
Luka
