CT-100 color sync issue?

[Phil Nelson]

I got a new NTE358 crystal and cleaned all sockets the Pete way. Cleaned the tuner, too, while I was at it.

The original crystal was certainly off frequency, judging by what happens when you swap crystals without changing anything else. Assuming the new one is correct, the other old crystals that I found are also off by varying extents.

I redid the color AFC alignment with new crystal in place. The picture is strong and noticeably more stable than before. I think the cleaning was well worth the effort. We still have evil color bands, though.



I turned contrast & brightness way down on this one to show how stable and well defined the color bands are.



Maybe I'm messing up somewhere in the color AFC procedure. The darned thing feels like it's so close to locking . . . .

Phil Nelson

[old_tv_nut]

Originally Posted by Phil Nelson

I turned contrast & brightness way down on this one to show how stable and well defined the color bands are.



Maybe I'm messing up somewhere in the color AFC procedure. The darned thing feels like it's so close to locking . . . .

Phil Nelson

There are 10 (maybe 12 with vertical retrace) color bands, meaning the oscillator frequency is off by 600 -720 Hz. So either the oscillator frequency is tuned this far off and the AFC can't pull it in, or there is something wrong with the phase detector [edit - or the reactance tube circuit] that is forcing it off to one side.