|
When the CRT bell is coated with aquadag (black graphite-looking stuff), there is usually a pair of thin wiry springs (sometimes one spring) that push onto it when it is fully installed. These connect to chassis ground, often through the metal yoke housing.
If the sound is a sort of faint hiss or fsst noise, it might be corona (high voltage arcing) somewhere inside the high voltage cage. Did you ever open that cage and clean the stuff inside? It's often covered with very fine, sooty dust. Rubbing alcohol cleans it off easily.
If the inside of the cage is clean, you could open it up and briefly power up the set with the room dark. HV arcs look bright blue or blue-white. If you see any, note the location and power down immediately, then investigate.
Phil Nelson
|