sorry you are so far away
I usally can troubleshoot these things when i can lay my hands on them. Tinkerer and electrical engineer...
The phrase voltage convertor makes me suspicious. Not all convertors are created equal. If it is heavy, and magnetic based, then likely it is good. Little power switching semiconductor things are a different story, particularly wehn lightly loaded, as this application could present.
Will the timer run without the enlarger plugged into it?
Is it possible to source a different lamp with the same color temp and form factor for the enlarger? Is the existing bulb 220V , or is there a step down transformer?
A lot of european technical stuff was made dual voltage, ready to be used all over the world with the change of a few internal jumpers. Usually this involves connecting the two primary windings of the transformer in parallel for 120V, whereas in 220V they are wired in series. Mind the polarity. The two windings have to add magnetically, and not cancel one another once paralled. This may be beyond your ability. I have cut over a slide projector, and a color analyser to 110V this way.