About a year ago I converted a 5" monochrome monitor's horizontal stage from mono TTL (18KHz) to VGA (31KHz). But these days I don't put as much effort into documentaion as I once did...
It's over on the shelf, so I'll have a look what I did to it. The yoke and horizontal output transformer are both original, but the transformer has a couple of external windings around the exposed core. I think there was one for boosting the B+ up to a higher votlage and the other winding was placed between the output transistor and the flyback capacitor. Authough it may just be there to increase/decrease the overall inductance. The flyback capacitor was reduced in value to keep the voltage on the aux windings at the same level.
There's a pretty hairy oscilator circuit to shape the horizontal pulse to the correct shape which feeds the output stage.
The compact mac monitors aren't hugely different from this little monitor. I think it would certainly be possible to increase the horizontal frequenct to VGA or even higher.
It's over on the shelf, so I'll have a look what I did to it. The yoke and horizontal output transformer are both original, but the transformer has a couple of external windings around the exposed core. I think there was one for boosting the B+ up to a higher votlage and the other winding was placed between the output transistor and the flyback capacitor. Authough it may just be there to increase/decrease the overall inductance. The flyback capacitor was reduced in value to keep the voltage on the aux windings at the same level.
There's a pretty hairy oscilator circuit to shape the horizontal pulse to the correct shape which feeds the output stage.
The compact mac monitors aren't hugely different from this little monitor. I think it would certainly be possible to increase the horizontal frequenct to VGA or even higher.