WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
Thank you for the schematic.
I own one which I bought 20 years ago and most of the copper tracks are oxidized (I was once lived by the sea-side for a couple of years) and it went dead just a few days ago because I shorted the power supply.