This has to do with an OMEGA D5 Dichroic enlarger we recently bought here in Spain. To the best of my knowledge, these enlargers all came with the US voltage and were rigged-converted to 220V. Mine has two big transformers. The problem is: the enlarger works correctly but makes a annoying humming noise from the head --different from the otherwise quiet humming noise of the fan itself. When we hooked it up to a third-party solid-state voltage stabiliser, the fuse pops on the stabiliser every so often. I suspect that these enlargers do not normally make this annoying humming noise. Can anyone verify this, and, has anyone had a similar experience with voltage conversions and-or voltage problems that could shed some light on this...thanks.