Quote Originally Posted by foto-r3
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.
Is the fuse blowing when you turn the lamp on, or while the lamp is operating? In either case, the stabilizer may be underrated for your load. If the power rating of the stabilizer is close to the lamp wattage, it may actually be underrated. The transformer will waste some power. The lamp will draw a very large inrush current when you turn it on.

Re the humming in the head: is there anything in the head besides the fan and lamp? Take a look with the power off. Are you sure that the sound is from the head? I could easily believe the transformers humming, perhaps you are having trouble localizing the sound.

A better solution would be to switch to a 220 V lamp and fan, or at least to switch the lamp so that you don't have to use a high wattage transformer. If Omega made / makes a 220 V version of the head, you could try finding out what lamp they used.