@creatorlars, would you mind taking look at this? Before I start tracing the signal or troubleshooting my layout, I just want to verify that there aren’t any glaring errors in my circuit. I omitted the AD724 NTSC/PAL switch circuitry, and I think I have the correct circuit for NTSC?
The goal is to have a simplified, monochrome version of C2 with an attenuator and luma output. My C2 is a little deep for my travel case, I never use RGB anyway, and my wired-up banana and BNC jacks were starting to bother me.
I’m getting a composite signal out, but it’s unstable. Ramps display correctly, but get torn weirdly when they’re processed. Oscillators seem to display properly when they’re h-synced at high frequency, but they freeze and stutter when v-synced at audio rate. My working theory is that my clock circuit is wonky somehow.
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The “14-pin header” is correct on my PCB even though it looks wrong – my way of avoiding 14-conductors is using 16-pin headers and installing the key backwards, but the cable/signals are connected where they need to go.
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Power to the ICs is all correct/measured/verified.
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No hot chips.
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The crystal cap is a 1% 10pF MLCC.
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The crystal reads “3.58 mHz” on the schematic, but it is in fact a [ABRACON +/-20ppm 3.579545MHZ].
Also, as this is basically a direct clone of the C2 – I have no intention to distribute it. Just for personal use, and will send one to the OP if I can get it working.
