I've just tried a spare 550VA 240V traffo from an NCC200 build in my Bedini 25/25. This one is a torroid and the original 115V is a 210VA EI.
When I flick the switch the transformer hums quietly as expected and then the ground lift resistor, that I installed from the centre of the PSU caps to the safety earth, glows orange and melts its insulation.
I quickly switched off the amp and haven't attempted a restart. The resistor is a 1W 10R and was added by me (with a 0.22uF cap in parallel) to get rid of an earth loop, I don't need it at the moment, so I could just remove it.
Why is it doing this? Is it normal to have a current flow to ground on startup (from the transformer centre tap)? Should it be a 5W resistor?
All helpful advice greatly appreciated
Dan
When I flick the switch the transformer hums quietly as expected and then the ground lift resistor, that I installed from the centre of the PSU caps to the safety earth, glows orange and melts its insulation.
I quickly switched off the amp and haven't attempted a restart. The resistor is a 1W 10R and was added by me (with a 0.22uF cap in parallel) to get rid of an earth loop, I don't need it at the moment, so I could just remove it.
Why is it doing this? Is it normal to have a current flow to ground on startup (from the transformer centre tap)? Should it be a 5W resistor?
All helpful advice greatly appreciated
Dan