sorry for my bad explanation. I saw, on the transformer of the preamplifier, that there are more wire on the primay windings, it seems that two 110 volt windings are connected in parallel but, if I disconnect one of them I saw, with a ohmmeter, that they are connected in some other way togheter. So I can't connect it in series to obtain 220 Volts. Probably it isn't possible modify the connection of the transformer.
Anybody have the electric diagram of the power supply?
Thanks for your time
Lino
Ciao