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there is one item worth mentioning, beginning I think on the CTC-15 there was an additional HV hold down circuit added. It works by take the rectified neg voltage from the blanker tube and feeding it back to the grid of the horz out thru a voltage divider. The Idea was if the HV shot up too high this hold down (the blanker got its voltage from the fly) voltage would bias the grid of the horz out more neg, cutting off the tube.
You can tell this when the grid of the horz out is TOO neg. esp if you have a scope and the wave form of the drive signal is normal (compared the neg reading at the grid).
what happens is the voltage divider (390k again IIRC) resistor on the chroma board loses its ground thru a very thin trace that runs right along the side of the board right by the HO tube. the trace cracks, the voltage divider no longer divides, and voila you get TOO much hold down. a simple test is to use the resistance charts for the blanker tube. if the grid resistance is too high its prob the crack in the board.
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