Blue Arc In The Neck Of CRT Picture Tube
If you come across any blue arcing in the internal part of the neck of crt picture tube then you can only suspect three faults. First is the bad picture tube (gas leaked) possible causing the arc across the internal section of the crt gun. Second cause is the too high for the high voltage causing it to arc to ground before the unit go into shut down mode. Third and the last reason is the defective flyback divider. I had came across many units with this problem where the focus voltage increased to more than 10Kv where it suppose to be from 2 to about 8kvdc. In order to isolate the problem, simply isolate it by removing the focus pin and power “On”. If there is no more arcing suspect a bad flyback divider.
If you want to permanently repair the problem, cut out or tape the focus and the screen wires and connect a Monitor blur buster. This way it will defeat the original focus and the screen (G2) voltage and use the good voltage from the newly installed Monitor Blur Buster.