[Apfelmus]

Thanks for all further advices.

So far I made the test proposed by Mark, unplugging the CRT. Not a difficult task. To my surprise, everything was nearly as before even without the load of the CRT (which I assumed should be the major part).

Looking at my thermometer (actually a thermal imager, a wonderful tool when debugging circuits) I noticed the current limiter always goes on when the HV transformer has reached 60°C. The temperature then settles somewhere at 65°C.

I also notices the HV diode D870 not getting warm at all. Once turned off I checked the diode, and its open circuit both ways, at least with my Fluke handheld. I wonder how the circuit can make the correct HV if that diode turns out to be broken...

I'll check that again with the CRT plugged in. I will also check C850 as advised by Leon. And I'll make a picture of the transformer, to check the "paxolin".

cheers
Martin