I( have a CRT Panasonic Colour TV )Model TX 68 R71 M16M Chassie.
I have audio I can change Channels, There is no vertical Collapsed. I only have Red and black colour and I can not change to any other colour except make the red darker or lighter.
I do not have a circuit digram . I have checked the transistors on the neck board and diods. Can you give me some advice as where to go from here.
If the TV is too old, then it might not be worth repairing. Also colour fault is not easy to fix.
You can test the tube by connecting a resistor say 470R between the blue or green cathode to GND (might have to experiment to lower resistance). The idea is to lower the voltage on the blue or green cathode. The screen should show up bright blue (or green) possibly with white lines.
Try this at your own risk.