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Charlie-
Regarding your earlier post (way earlier) about horizontal lock, my 15 had a problem that required twisting that coil to warp things back to the correct frequency.
The symptom was this: To set things up you are supposed to short the sync test point (to kill the sync) and short out the sinewave winding of the horizontal oscillator coil. You then adjust the horizontal hold to make the picture stand straight up.
This is the part mine wouldnt do. "Straight up" was off one end of the control.
When you have that, you remove the jumper from the sinewave coil, and adjust the sinewave coil until the picture stands straight up. Then remove the jumper on the sync point. Picture should lock.
It about drove me nuts. I thought that some component in the oscillator had to be at fault. Not so. It was the .0015µF mylar drop that couples the oscillator to the horizontal output. It had gone way up (!) in value. I have an old book around here somewhere that says a common failure was for this cap to go down in value, and the symptom was burned up horizontal outputs or flybacks, due to reduced horizontal drive. If you havent replaced this cap already, maybe take a closer look at it.
Regarding the "too dark" symptom. Have the video tubes been checked for gas? These sets have partial DC coupling all the way from the video detector to the CRT. A little grid current can screw the brightness all up.
All the best,
John
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