Video Selector Issues

[JohnnyOC]

So I read on the product page that the D9/Sync Only combo is the only invalid output, and the rest are valid. Well, for some reason, my situation seems to be that D9/Sync Only is the only valid output, outputting both the sync and overlay signals, and the rest always output both signals as well, except the overlay signal is all kinds of messed up, even though I can generally see what’s going on (whether a text or graphic is on the screen.) I tried adjusting the potentiometers, but nothing happened (not that I really thought it would, I was just desperate.) Any ideas?

[Michael]

Hmm. so you are saying that even with the OUTPUT SELECT switch in the SYNC ONLY position, your input video source is passed through to the output? It should not be. This switch controls whether the input video is also included in the output. In the “SYNC ONLY” position, only the text/graphics generated from the code should be in the output signal.

The SYNC SELECT jumper set to D9 is for the case when you want to generate graphics, but don’t have any video source connected to the input. That is, the Arduino generates the synchronization pulses on the D9 pin.

Is this making sense?

[JohnnyOC]

Yes, what you’re saying does make sense, but it’s not working as it should. D9/Sync Only is passing the video input source through, and ALL options are overlaying, the complementary three options giving garbled overlay. Just wanted to make sure I wasn’t doing anything incorrectly, cause I think I can make it work for what my class project requires.

[Michael]

I think we are using the term “overlay” differently. The text and graphics that your code generates *should* be present in the output for *all* settings. The switch setting “OVERLAY” means that the input should be included in the output such that the text/graphics is overlayed on top of it.

If the video input is passed to the output when the switch is set to SYNC ONLY, then there is a short. Have you looked at the soldering for the switch and jumpers?

I expect garbled overlay when the switch is set to SYNC ONLY and the jumper is across the middle pin and leftmost “D9” pin. You are connecting the jumper so that it connects the middle pin and either the left pin (for D9) or right pin (to use the sync signal from the input), correct?

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