Modifying to 220V operation. How to make sure?


Taking the bottom cover off my VTL MB100 I've noticed the extra set of isolated wires from the power transformer.
I called the manufacturer and they were not able to be clear since they do it usually as extra feature having an option to re-wire the unit to 220...240V operation.
There is some plan on how I plan to verify that the unit will operate at 240V and I want to discuss it.
1. Make sure that rectifying bridge is able to operate at 240V if not than I would have to replace it(or even upgrade).
2. Take off all tubes
3. Reconnect wires from the power transformer and turn on the amp into the 220V receptacle.
4. Check Cathode voltage from the tube sockets(Is it safe to run amp with no tubes? What issues am I facing here?)

If I need to replace bridge what parameters should I provide the manufacturer(of the bridge) becides input-output voltage and tolerance%?
128x128marakanetz

Showing 2 responses by marakanetz

Thanks Twl!
It's simple and genius.
Whattadumb i am! Bridge, Cathode voltage... it's far more simplier.
Thanks for warning working with high voltage. I take all precautions not to get electricuted.
You might also be right about VTL people that by default are not sure if I can deal with high voltages(AC is even more dangerous than DC) and I don't blame them. In all other cases they provide an excellent customer service.
Herman, I have textbooks and I'm able to read the circuits.
It's much tougher to do it without a circuit diagram knowing only basics. I tend to know as much variables as possible in order to start or not-to start at all.
Twl's responce seems to be the safest. All it needs to be done(to avoid electricution) is to newtralize caps by simply shorting them(using isolated screwdriver) when power is off and than start to examine transformer output voltage without even taking off the tubes.