Verify that there is a good solid ground path from the crt safety band mount to the analog board ground, close to zero ohms. Viewed from the rear, the ONLY path is from the upper left band mounting screw thru the terminal lugged black/white wire to the B/W pad on the upper left corner of the CRT neck video board next to C2, then out the black wire of the ferrite sleeved harness to pin 3 of the analog board video board connector P2.
The aquadag is grounded to the mounting band by a conductive coating, and should measure in the low to mid hundred ohms probe tip to ground. If it floats the internal CRT anode capacitor (approximately 700 pF) is compromised (to about 150 pF), and the HV could vary more during each scan line as the video presents a varying load. If someone did a CRT swap and the replacement lacks continuity from the graphite coating to the safety band zone, you should improvise a contact with a spring and some bare wire.
That black/white ground wire crosses the extremely well insulated red wire of death [
] ]'> and it would be best if the b/w wire hugs the aquadag and the red wire floats above it as not to concentrate voltage stress at an insulation point of contact.
The aquadag is grounded to the mounting band by a conductive coating, and should measure in the low to mid hundred ohms probe tip to ground. If it floats the internal CRT anode capacitor (approximately 700 pF) is compromised (to about 150 pF), and the HV could vary more during each scan line as the video presents a varying load. If someone did a CRT swap and the replacement lacks continuity from the graphite coating to the safety band zone, you should improvise a contact with a spring and some bare wire.
That black/white ground wire crosses the extremely well insulated red wire of death [
] ]'> and it would be best if the b/w wire hugs the aquadag and the red wire floats above it as not to concentrate voltage stress at an insulation point of contact.