Half bridge protection measures

[John123]

Is the flyback getting warm? Maybe that 30 watts idle is from a shorted turn after the incident, secondary can internally flashover and use of enameled coated wire for primary can sometimes short to the core at the corners (core electrically conducts like a resistor in the kilo ohm range).

[Sk1ppy]

That may be a possibility - the primary coil did get rather warm, and my other flyback doesn't get nearly as hot

[John123]

What sort of wire are you using for the primary coil? Enameled magnet wire has a habit of scratching and shorting to the resistive but conductive ferrite core.

Just came across this https://4hv.org/e107_plugins/forum/forum_viewtopic.php?p=1&id=173600#post-173600

Well , although that seems to work good enough for DC, as most of us know, once flyback diodes are broken and the output is AC, corona quickly damages the innards of the flyback and it mysteriously heats up and reduces in output, unloaded!.

[Sk1ppy]

I'm just using regular plastic insulated hookup wire, somewhere around 20awg.  I had about 10 turns on the primary.