20-07-2011, 09:17 AM
When AC sets buzz as soon as power is applied rather than when they are warmed up it is usually a case of the transformer laminations buzzing. Sometimes it is possible to remove the transformer and boil it to get all the old wax off and then cover it in fresh wax in the hope it will reseal it properly. Very annoying if it can't be fixed though as it means a perfectly functioning transformer needs to be replaced.
