Modify an old VCR TV modulator to channel 5

[wa2ise]

Originally Posted by jeyurkon

I wonder if you're the first to modify a CM7000. They've been out for less than a year haven't they?

John

Oh, some people were trying to reactivate the digital audio output jack, but it seems that the firmware has it disabled. And there are missing driver circuits. I made that jack a mono audio output, by the simple expedient of a pair of 10K resistors adding the left and the right channels together.

And I figured out how to make this box be a B&W only source for our vintage pre color TV broadcast standard (before RCA's NTSC color, which came out late 1953) sets. Many of those sets could present the entire 4MHz of B&W video on their CRT screens. And the chroma subcarrier would show up as a crawling fine checkerboard pattern on such sets. This switch just removes the chroma subcarrier from the composite video, and that feeds the TV modulator, both the OEM one, and my replacement.

You can see that I did this to the CM7000 a few posts ago while I had it apart, the green and yellow wires.