That's interesting. Thanks for the measurements.
So the amount of the interference checkboard pattern could be a hint to the sine-like-quality of the signal?
You can clearly see that the 8565R2 has the most evenly color allocation. We know that also from previous measurements. Esp. the lead color
brown has no difference here for odd/even.
The term under the chip rev. is the modulator "revision"?
So from left to right ist is board-1, board-2..., right?
The VIC-II chip does not output true sine waves. The newer modulators have a low-pass filter in the chroma input that resonates at the color carrier frequency. That will make the color signal look more like a sine wave. As far as I can tell the original modulator did not have this filter.
One theory could be that the resonance in the filter also increases the output voltage.
Could you capture the sine signals both in shape and absolute value for the board-1 and board-5? Each color burst and lets say green color amplitude. Each odd/even. If you want, each composite and chroma output. ![]()