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That makes sense. The CRT is closer to cut off and the wiper is at the ground end. Placing a little plus DC bias on the CRT control grid will centralize the control. The diagram is cut off but I suspect the grid goes to ground through a resistor with a coupling capacitor from the vertical output transformer feeding it?
Placing a single additional high value resistor between the +250v rail and the CRT control grid will form a resistive divider which should apply a positive bias of roughly +20 volts on the grid. This will bring the brightness control closer to the center of its range.
Last edited by Penthode; 04-03-2020 at 02:57 PM.
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