CT-100 B1001599 Failed Convergence Transformer

[Penthode]

Originally Posted by old_coot88

Given that the xfmr's secondary sits at focus voltage, making a ss replacement would be an interesting design challenge.

It would be an interesting challenge. I only wish I had the waveforms the circuit would deliver. It would make the problem somewhat simpler.

It looks like the circuit including the transformer is generating only the vertical parabola. The brown lead would be at sinal ground by virtue of the 0.01uF capacitor from the brown lead to groundwhich means the parabola would would have a slight application to the focus electrode, likely to modulate the focus perhaps? and a much greater amplitude which would be coupled through the 820k resistor to the convergence electrode. Which means a single amplifier fully sitting above ground by 4000v coupled with some voltage gain (by virtue of the step transformer) from the output of the 12AU7. Hi voltage coupling capacitors and some diode spike protection should make it work. Afterall, the dynamic convergence correction should only be slight. I am going to think on this.