Vintage Synth Repair

I have resolved to use a step up transformer to power my newly
acquired Roland System 100 Mixer (25 watts).  Can anyone recommened a
good brand/source for one that will receive an Australian three-prong
plug (three flat pins/two angled off axis) and convert 110-120V (US
wall) to the necessary 240V (unit)?  I've had a Voltage Valet travel
converter burn up on me before and destroy an electric razor...rather
not have that happen to a vintage synthesizer!

thanks-stephen