Hi Tom,
Thank you for the advice!
As you can imagine I played arround with the geometry and the rotation adjustment trimmers. That didn't help. A desperate idea was to turn the CRT a couple of degrees in counterclockwise direction and to adjust the rotation. Of course this is mechanically not possible. A deeper diving into the problem unveiled, that even turning the CRT wound't help.
It should be an influence of the X voltages by the Y voltages or the supply voltages. However, I measured the supply voltages, which seems to be very stable, and also the voltages at the starting points of the staircase lines shown in one picture and the end points. All starting point voltages and respectively all end point voltages are the same. The voltages are measures at the inputs, in the middle and at the output stage of the X amp. So the problem may be caused by an internal defect of the CRT by tilting the X deflection plates for some degrees. But how can this happen during normal use? May be there is a defect during production of the CRT. Unfortunately I now nothing about the history of the 7613.
Regards
Loetroelli
