maybe you get the lightweight plastic ones there.ours have heavy transformers and steel cases.some have fans.
the ones built into a plugstrip and the "cs" series are junk.mosfets on chunks of aluminum.light transformers.
its about to melt down at full load right as the 7ah battery is done.trash.
i will let you guess what we think the "cs" means.
In 90's were available only the rather large and quite heavy units.
MOSFET's were always fine, they usually do not dissipate much power (due to their low Ron).
What always burned out, were the transformers and only transformers.
I don't know, how differ the 50Hz vs 60Hz types, but in all units I repaired, the transformers had the "230V" winding made of two equal sections connected in series, what suggest the transformer is of common type for both 230V/50Hz and 120V/60Hz areas, only differ in the connection of the mains winding sections (parallel for 120V, series for 230V)
That would mean the 120V/60Hz version have extra margin towards reaching the core saturation, what make them more resistant towards high temperature (because the higher frequency, the magnetic flux in the core is ~20% lower, so tolerate further 20% reduction of the core saturation flux, what mean higher temperature necessary to start the thermal runaway).
