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Old 09-05-2023, 01:28 PM
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Electronic M Electronic M is offline
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Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
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Quote:
Originally Posted by LukeSimon View Post
I tried fine tuning again. Turned color gain off, so picture is black and white. Then rotate fine tuning clockwise until I start to see wormy sound in the picture, then I slowly rotate counterclockwise just a tiny bit until the picture stops being wormy. The black and white picture looks sharp, but when I turn color gain up to a normal level, the color smearing becomes visible. Fine tuning counterclockwise makes the color smear much worse. The tint control has very little range, and color gain almost has to be set to its lowest setting, otherwise the picture is too saturated.

All tubes have been replaced with tested NOS tubes, except the 25XP22 picture tube which is used but tests very strong cutoff, very strong emissions, and no shorts. Also, I did the Sams chroma AFC alignment, which tunes the chroma oscillator, so it locks in the color signal even on a weak signal. I have not performed the chroma bandpass alignment or the 4.5mhz trap alignment.

What should I try next? A chroma bandpass alignment? I have a B&K 415 and an oscilloscope, but I have never used the B&K 415 before.



I think this is either ghosting in the signal path between the generator and antenna input, or an IF alignment / video peaking problem. The picture above on the top numbers you can see that the number has synchronized luma and chroma, but then next to the numbers there's (EDIT lumina and) chroma ghost numbers where it should be dark. This is some kind of ghosting/ringing effect somewhere.
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