ASR-33 conversion to 220V

On 8 Dec 2006 at 0:32, Tony Duell wrote: I own a Toshiba microwave oven (with 3-prong grounding plug) that will not power up if the mains socket is wired up with the feed reversed. Drove me crazy the first time I tried to use it until I discovered that the idiot who wired the kitchen receptacles swapped black and white at one socket in the string. The same refusal to work may be true of some ground-fault interrupter receptacles (i.e., they always stay "tripped" if wired backwards). The local Cheap Chinese tool place regularly has a special on receptacle testers that make sure that the wide blade in the receptacle is at ground potential. At what level does this not hold true? For example, I've got a nice big router (portable) that draws a full 15 amps at 120v at startup. That would be a pretty large transformer. Nowadays, however, most portable tools are simply constructed as "double insulated". Cheers, Chuck