Looks retro,nice valves. Is that a ht diode with the cap on? The other's not a double triode. Electrostatic deflection on those or a yolk?
Very playaboutable.
Yes, that is a HV tube, 1Z2, filament and plate only. The other is 12AX7, dual triode.
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This visibility of those parts of the trace are indicative of a slow edge on the blanking / intensity signal. You'll need a real scope to see that.
There is no blanking,it simply steps to a new position and pauses for each dot in the display. If I turn down the intensity a small amount, the retrace lines disappear.
I am still working on the circuit (tracing out the board).
EDIT: I will scope the control signal on the cathode ckt and see if there is any blanking attempt.
My correction: I believe it is blanking between dots, but it will take me awhile to figure this out. I will post some scope images later of the control signal from the uChip and after the HV conversion. to see what distortion takes place in the HV circuit.
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Well, from the attached waveform it is obvious (I think) that the circuit is very slow on turning off the beam, so between dots or groups of numbers, it just isn't fast enough. I think I know a way to fix that since it is just an open collector drive to the cathode (????). Maybe just some pullup resistor.
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Well criminy, I need to figure out which way is on and which way is off. Be back later with an update.