Graetz Faehnrich color

[yagosaga]

Originally Posted by roundscreen

Even with weak contrast the k 7 has a nice picture. What was the reason that the ground was missing to the controls? Broken wire or a trace on the board?

Somebody has removed a ground connection from the tuner board. I have replaced it.

Meanwhile I found the reason for the low contrast. This set works with a shunt regulator and a beam current control: the high voltage coil is connected with the contrast automatic via a diode. When high voltage increases, a negative pulse is given on the grid of the tube for contrast control and keeps the peaks of the video signal low. In this unit, there is a beam current control potentiometer. I have adjusted this potentiometer and so I got full contrast. In the attachment is a screenshot, now with full contrast (correct: with contrast control in middle position).

A convergence failure was also fixed (no horizontal parable voltage and therefore no convergence at both sides of the picture).

Originally Posted by roundscreen

Are you working on the east German set?

No. This set belongs to a friend of mine. But he made the photos for me.[/QUOTE]

Originally Posted by roundscreen

Also why is the 21cyp22 yoke and convergence assembly turned to the left? Vary interesting.

I think that somebody has disassembled the set and assembled it again without knowing the correct size of the yoke.

Eckhard