VHF Tuner Alignment: where is the overall oscillator adjustment?

[LukeSimon]

Originally Posted by Yamamaya42

It DOES say to de-tune FT until a beat pattern is seen (herringbone pattern ) , then adjust for minimum, so it can't hurt to try, I'm more curious about the slight mirroring seen to the right of the characters/ letters seen on the BW screen, mine also has the same to a lesser degree, no idea of the cause however.

Remember, I have two Magnavox’s: a 1967 T931 and this 1968 T933. The differences between the two chassis versions are very minor. The T931 doesn’t have this issue, and when I look at how the core of the 4.5mc trap is screwed down into the adjustable transformer in the T931, and how it is poking up outside of the T933, I am starting to wonder if I should fine tune into a very wormy picture and then screw the core into the 4.5mc trap so that the picture isn’t wormy. The color smearing goes away if I fine tune to a very obnoxiously wormy picture.

Smeary T933’s 4.5mc trap core is poking out of the coil.


No smear T931’s core is screwed down into the center of the coil. According to the Photofacts, this part number is identical between both chassis versions. In fact, this part of the circuit (video detector) is identical in both chassis versions.


T933’s color smear goes away if picture is tuned to be wormy.


Sams says that 4.5mc trap should be aligned by fine tuning to a very wormy picture, and then adjusting the core util the wormy interference is minimized. So once that is done, I may be able to fine tune to zero worminess and near zero smear.


Since I was fine tuning CW to a wormy picture and then fine tuning CCW until not wormy, I may simply be not using the proper fine tuning because the misaligned 4.5mc trap makes the worminess excessive too early in the fine tuning CW rotation.

[old_tv_nut]

Originally Posted by LukeSimon

...
Sams says that 4.5mc trap should be aligned by fine tuning to a very wormy picture, and then adjusting the core util the wormy interference is minimized. So once that is done, I may be able to fine tune to zero worminess and near zero smear.


Since I was fine tuning CW to a wormy picture and then fine tuning CCW until not wormy, I may simply be not using the proper fine tuning because the misaligned 4.5mc trap makes the worminess excessive too early in the fine tuning CW rotation.

Sorry I didn't see this before.

Yes, with the core so obviously misadjusted, it makes sense to try adjusting it. But if you can;t improve it by adjusting the core, you will need to look for something else.