[peter_scott]

Thanks David,

The circuit has 10k and 0.001uF so 10uS. I changed it to 50uS for the photo in my last post. Actually I've probably gone over the top because the feed isn't direct from the sync sep anode. The load is split 39k from the rail and 27k to the anode so my 10k is probably more like 26k so it started life with a 26uS time constant. I should have just doubled the capacitor size.

Peter

p.s. Just reduced my capacitor to a doubling in value and it does work fine.