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While you are at it.........
There is a capacitor that WILL need to be replaced on your JVC.
It is in the pump-up ckt for the output of the chip. By now, it is surely leaky and of high ESR.
look for a 100uf at 35 volt capacitor off of the la7830,36,38, 7841 or whatever output it uses. It will have one lead connected to the cathode of a diode,(with B+ on it) and the other lead will go to the IC.
I could explain what the "pump-up" ckt is, but to put it in layman's terms, it gives the vertical output ckt. some "free" power obtained from the yoke during retrace period. IOW, it is like a "turbocharger on a small engine," that gives it way more power than it normally would produce. But when it goes bad, at first, it will cause a shrinking picture, probably with lines at the top or middle, and then, it WILL kill the chip.
So, while you are in there- REPLACE that cap!!
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