25 Jul
2018
25 Jul
'18
8:32 p.m.
There are, however, DEC products other than the RK05
which had different
transformers for 50 Hz and 60 Hz. For example, the H771 power supply used
in the RX01 and RX02. There were three H771 models, The H771A for 90-132
VAC 60 Hz, The H771C for 90-132 VAC 50 Hz, and the H771D for 180-264 VAC 50
Hz. The H771A uses a transformer rated for 60 Hz. The H771C and H771D both
use the same 50 Hz rated transformer, with different wiring. The H771C and
H771D also require one of two different wiring harnesses to cover the
entire mains voltage range, e.g., 90-120 VAC vs 100-132 VAC for the H771C,
or twice those voltages for the H771D.
IIRC that's a ferroresonant transformer (with a capacitor to resonate one of the
windings to a harmonic of the power line frequency), so it's not
surprising it has
to be changed for 50Hz or 60Hz input.
-tony