Hi All,
My Video ( NTSC ) output (AV) seems not stable, when I keep a static picture there, I can see the picture is flashing ( something like the backlight flashing, about 10Hz...measured by my eyes.. )
How to check the video signal is stable or not?
Want to make sure that is power problem or circuit protect problem....
Best regards, Boki.
Down load the NTSC timing specifications, and check your signal with a scope, quite often published in philips semiconductor video IC specs, it sounds as if you have a major timing problem
Get a proper TV signal from a TV tuner, and lock your oscilliscope to that, put your AV signal on the scope and see how quickly it drifts across the screen , or hire a Tektronixs(sp?) wavefrom monitor
martin
Maybe something is running at 50Hz vs 60Hz, or the other way.
-- john
This sounds like a problem witht the monitor. The video signal itself is probably not the problem. I had a Radio Shack TV/Monitor that used to do this.
Luhan
Dammit, misread the OP, I thought Boki had created a video signal with a micro or some such evil device, and had problems with the signal
martin
About 10 HZ sounds like you're seeing a beat between the power line and the vertical oscillator. Check the power supply for ripple.
Oscilloscope.
With your scope, look at the video itself - I've seen scopes that have "TV V" and "TV H" horiz. sweep settings; one syncs up to the vertical, the other to the horizontal, so you can see a side view of the frame or a top view of the lines. ;-) Any instability should show up there.
Also, use the scope to check for ripple in the DC, both in the video source (although, if that were the case, you'd have seen it on the video itself) and in the monitor.
If they're all OK, I'd start looking for an interconnect problem, and so on.
Good Luck! Rich
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