See attached schematic.
I started off by removing the barrier strip from the right channel, and installed two binding posts. I connected the binding posts to the 8 ohm transformer tap, and the 0 ohm tap, along with the (feedback?) wire that goes from the 0 tap back to the junction of R9 and R14.
When I first completed the work, I had output, but it was quiet. I've since fiddled around, trying to take measurements, and observe different connections. I fear I may have caused some further problem, because now I get voltage across the posts, but it drops to zero as soon as I connect a load (and I get no sound from the speaker).
When I was fiddling around, I occasionally observed a high pitched whine coming from the output transformer when I connected the ground probe of my scope or meter to the 0 ohm post. I also observed very high voltages when measuring between the 0 and 8 ohm posts, on occasion. Further, on some occasions touching the 0 ohm tap to the (feedback?) wire caused my source equipment to fritz out.
I have checked and rechecked the wires I'm using. I'm utterly baffled why any of this should have occurred. The posts may have been shorted to the chassis on first assembly, but they are not now.
I'm sure there are many bad things I may have done. I would appreciate suggestions on how to test and verify what I may have screwed up.
I started off by removing the barrier strip from the right channel, and installed two binding posts. I connected the binding posts to the 8 ohm transformer tap, and the 0 ohm tap, along with the (feedback?) wire that goes from the 0 tap back to the junction of R9 and R14.
When I first completed the work, I had output, but it was quiet. I've since fiddled around, trying to take measurements, and observe different connections. I fear I may have caused some further problem, because now I get voltage across the posts, but it drops to zero as soon as I connect a load (and I get no sound from the speaker).
When I was fiddling around, I occasionally observed a high pitched whine coming from the output transformer when I connected the ground probe of my scope or meter to the 0 ohm post. I also observed very high voltages when measuring between the 0 and 8 ohm posts, on occasion. Further, on some occasions touching the 0 ohm tap to the (feedback?) wire caused my source equipment to fritz out.
I have checked and rechecked the wires I'm using. I'm utterly baffled why any of this should have occurred. The posts may have been shorted to the chassis on first assembly, but they are not now.
I'm sure there are many bad things I may have done. I would appreciate suggestions on how to test and verify what I may have screwed up.
That circuit uses the output transformer secondary for cathode feedback. The 4 ohm tap needs to be connected to earth, with output tube cathodes connected to the 0 and 16 ohm taps along with balanced feedback back to the input stage (with respect to the 4 ohm tap these have equal but phase inverted signals). The speaker binding posts would be connected to the 0 and 8 ohm taps as you have, but it is important that neither of these are connected to earth. To measure output with a scope you cannot connect the ground lead of the scope probe to the 0 tap.Either observe each half of the signal with scope ground on the 4 ohm tap and signal on 0 or 8 ohm taps, or use 2 scope channels on the 0 and 8 ohm taps and set the scope for differential mode.
