28-06-2020, 06:56 PM
I have tried disconnected the CT to the heaters (white cable). Made absolutely no difference with regards to the mains hum.
I reconnected the white cable and disconnected the red/yellow centre tap. I am sure after a few moments I saw a flash in the rectifier tube followed by no hum or any noise whatsoever. Interestingly all of the valves where still lit up but even putting the volume to max there was no hum and no output to the speaker (I tried with a jack plug connected too but no output).
I reconnected the red/yellow CT with the white CT - no output again. I changed the EZ81 and again the mains hum reappeared. Obviously, I've damaged the old EZ81 albeit it was still glowing.
I would try this without the earth connected but I am concerned that I might blow another rectifier valve.
What does this suggest??
I reconnected the white cable and disconnected the red/yellow centre tap. I am sure after a few moments I saw a flash in the rectifier tube followed by no hum or any noise whatsoever. Interestingly all of the valves where still lit up but even putting the volume to max there was no hum and no output to the speaker (I tried with a jack plug connected too but no output).
I reconnected the red/yellow CT with the white CT - no output again. I changed the EZ81 and again the mains hum reappeared. Obviously, I've damaged the old EZ81 albeit it was still glowing.
I would try this without the earth connected but I am concerned that I might blow another rectifier valve.
What does this suggest??
if all else fails...read the instructions!
