Quote:
Originally Posted by vts1134
I thought that the Horizontal AFC was the horizontal frequency adjustment. Is there another adjustment that I'm missing?
Adjusting fine tuning, horizontal hold, and horizontal afc the picture below is as close as I can get. The pattern should only be three vertical white lines on a black background.
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Well, AFC stands for "automatic frequency control" which is the function of the first section of the tube (the second section being the oscillator). The AFC section takes the sync signal and compares it to the oscillator's signal and then automatically adjusts the oscillator up or down to lock it to the sync signal. (The 'horiz. hold' control {R7} adjusts the locking range of the AFC).
Anyhow, the oscillator should be running at 15.75khz. If the oscillator is 'waay off but running at some integer of 15.75khz, the AFC section can lock onto that. And that's apparently what's happening.
It's hard to tell from that screen photo if the osc. is running above or below the correct frequency. The oscillator's
frequency adjustment is that coil B1. Adjusting B1 should bring the osc. to the correct frequency unless something's seriously out of whack.