Warren,
this question has been asked again and again on these pages and with a bit of searching you would find all the necessary information.
The simple answer to your question is: Yes it can mostly, but there are exceptions. Often all it takes is throwing an inner switch or changing and resoldering a few wires on the transformer. Bring your amp to a qualified technician. He'll tell you if it is possible and do it for you. Remind him to exchange the fuses after he has done the job. Sometimes they forget......