Convergence ?

[old_tv_nut]

Originally Posted by Electronic M

Small changes in sweep scan probably effect it too, changes in line voltage and tube aging will effect the amplitude and linearity of the input waveforms which should change the output some.

This is true, but not so much due to the input waveforms affecting the output waveforms (which are heavily filtered to get the parabolas), but the fact that the distortions in the input waveforms are higher frequencies that do not carry through to the output. Thus, the spot is in the wrong position for the amount of convergence current when the linearity is bad.