Roundie left edge purple

[kx250rider]

I vote that it's a mild horizontal drive problem causing a ghost foldover, and definitely a horizontal problem of some sort. I strongly doubt purity, although I suppose that's possible if the purity rings and yoke are set really weird.

Charles

[DaveWM]

horz drive alright, just had the bias set too low, the reduced scan size must have been unequal on the guns, it was under scanning on all, just a bit more on the green. Better pic, and no purple.

it was underscanning on all guns you could see the black edge on all colors just a bit more black on the green.

I will check the anode voltage and HOT current to make sure its in the safe zone.

does it make since that the green gun would scan a bit less due to the contsruction of tube? I am thinking angles of deflection and electron gun placement.

the way it was setup there was under scanning and not over scanning.

[DaveWM]

cathode current is about 250-260 should be 220 per the schmatic. that is just enough bias to get the full scan. brightness at normal levels.
reducing to low bright low contract gets it down to about 245ma.

low brighness if fine for viewing now. Before it would completly cut off.

High brigtness is good, more than needed now with adjustment.

[DaveWM]

there is a 5.6 ohm resistor in series with the horz yoke drive wire. I am going to check that to make sure it has not drifted causing too much of a voltage drop and resulting in a loss of scaning. there is also a 'centering" diode across the resistor, not sure what that is about.