Jim Land wrote:
Matthew Kirkcaldie wrote in
:


Having found an open primary in the small transformer ....



That's strange. Transformer primaries don't open very often. I would be
inclined to dig deeper to find out why there's an open circuit (internal
fuse open? Bad connection? Melted wire?) and whether there is any fault
downstream of the transformer (shorted component?).


Small transformers are impedance protected, the windings can be damaged
by power surges or an overloaded secondary. If the unit works after
replacing the transformer, it was probably just a surge that popped it.