Osborne Vixen - Zenith 7" display t-shooting issues

[tony duell]

>
> >
> > This sounds thermal to me. Somethng is failing when hot. Maybe the HOT. Maybe
> > a diode or capacitor in the horizontal output stage.
> 
> Probably not a power supply issue, per se.  Usually, when power supply
> voltage drops, the image shrinks on the screen.

Be careful... a low supply will lead to low EHT (HV, final anode voltage, whatever you call it) which 
means the electron beam is less stiff. So it will be easier to deflect. This will compensate for the low
deflection amplitudes, depending on the monitor the picutre may grow, shrink, or stay about the same
size. 

-tony