I just decided to test the voltages in my old tube guitar amp against the schematic. I live in Australia and it's a US amp, so I use a separate 240-110v step down transformer to run the amp. Upon testing the amp, I realised there was around 240v between the chassis of the amp (grounded) and the neutral line. I went back to the step down transformer and got the following readings
~110v between hot and neutral
~130v between hot and earth
~244v between neutral and earth
My wall plug is fine, with ~244v between hot and neutral, ~244v between hot and ground, and 0v between neutral and ground.
Does anyone know what's going on here? I've left the amp in bits and I'm not playing it until I've worked this out, as it seems I might end up playing with 240v on the guitar strings! Thanks in advance