VHF Tuner Alignment: where is the overall oscillator adjustment?

[old_tv_nut]

It should be easy to check the coils for opens and also check that the connection to the sharpness control is not open.

BTW, I'm scratching my head about how that sharpness control is supposed to work. Where does the luminance signal go next (which tube and what electrode of that tube)?

[Yamamaya42]

Originally Posted by old_tv_nut

It should be easy to check the coils for opens and also check that the connection to the sharpness control is not open.

BTW, I'm scratching my head about how that sharpness control is supposed to work. Where does the luminance signal go next (which tube and what electrode of that tube)?

I find it a bit confusing too, but it DOES do something on my set.
http://suzaku.live-evil.org/maggie-video.jpg
however the control WAS very dirty at first, and needed 2 cleanings before it would work on my set.

you could try to short the top (input) point to ground to see it that makes any change.

[LukeSimon]

Originally Posted by old_tv_nut

It should be easy to check the coils for opens and also check that the connection to the sharpness control is not open.

BTW, I'm scratching my head about how that sharpness control is supposed to work. Where does the luminance signal go next (which tube and what electrode of that tube)?

The 6LM8 acts as a cathode follower for the luma signal. So luma is output from its cathode and that is input to another luma amplifier. Dialing up the sharpness pot decreases the load resistance of the cathode follower amplifier which reduces its gain but increases its bandwidth.

I will clean the pot. While I am at it, I will try a few alternative tubes. Even though my NOS 6LM8 tests good… in the chassis performance can still vary.