GanjaTron wrote:


Well, the xformer does churn out the 4VAC unloaded BUT I can't measure any
continuity in the secondary, which is unsettling. Am I getting some
spurious induction from the other windings?
OK, then, there's your problem. Apparently, the transformer has
an open winding. There may be enough capacitance that the meter, in
Volts mode, picks up about the right voltage (with a 10 Meg Ohm load)
but that the transformer can't deliver any current. You can check the
terminals to make sure the windings are soldered well to the pins (assuming
this is a typical PC board mount transformer, that is usually pretty easy
to do.) If you are really lucky, it may be bad soldering at the
terminals, where the windings are soldered on. If not, then you
can try to figure out how to get the required voltage from a tiny
add-on transformer. The filaments of typical VFDs do not even need to
light up at all, visibly, to produce electrons.

Jon