Can an ADCOM GFA-5802 be converted to 220V

Any electronics can be converted to 220v. 1) Use a step-down transformer. 2) Get a replacement transformer that has a 220v primary, but with the secondary(s) the identical output voltage. Also, the fusing needs to be halved.

#2 above is harder to do - obviously someone who knows how to work on electronics is required. #1 would be your best bet if you can't do #2.

Ask Adcom if the transformer has a split primary winding (so that it can work on 110 or 220 simply by wiring the windings in parallel or in series). This is very common in modern electronics, and sometimes the connection is changed just by moving a jumper (or even a switch).

Adcom can give you the details of rewiring the large toroid transformer and setting jumpers for the smaller control transformer as well as fuse replacement. I changed my amp from 220V to 120V.