Gareth Magennis wrote:


... and check that the creepage distances, clearances, insulation etc. of
the 120V PSU's isolation barrier are adequate for 240V operation.


The 120v PSU is receiving 120v from the autotransformer.


** That claim is only generally true for isolation step-down transformers.

With an auto-transformer, it DEPENDS on getting everything right all the time.

The supply neutral must remain connected to the neutral side of the auto tranny AND the neutral side of the appliance's AC connection.

A simple loose connection on the neutral pin of the plug means that 240V AC appears on each AC conductor in the appliance. Sure, the appliance does not work but that is no barrier to insulation or AC side capacitor failures.

I would never suggest using an auto tranny step-down with any appliance that did NOT have a 3 wire lead with safety ground connection.



.... Phil