Transformer Fault in a PSU?

Rob Jarratt robert.jarratt at
Sun Jan 12 15:10:09 CST 2020

The PSU in my VAXmate failed recently and I think I have found a problem
with one of the windings on the transformer not ringing when I test it with
a ringing tester. The technical description of the VAXmate says that one
winding is operated in flyback mode and I wonder if that has any bearing on
the ringing test. Also, one of the pins appears not to be connected to
anything else, so possibly a broken (melted?) wire.


Can anyone help with the following questions:


Does the fact that one winding is operated in flyback mode have any bearing
on the ringing test?

Can a transformer fail with a bad smell with no outward sign of damage?

Can this transformer be replaced (see picture in blog)? - I suspect not
unless I find a donor PSU.

Where should I look for a possible cause of the transformer to fail (if
indeed it has failed?).


I have posted more details here:






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