Slight problem with PAL video generation (Circuit done)

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PauloConstantino

Joined Jun 23, 2016
266
Hi friends,

I have finished my circuit to display composite monochrome video signals onto a TV. I can see that the TV is synchronizing to the signal, however the TV shows a white screen. I am not sending any pixels to the TV yet. I am only sending synch pulses. The problem is that I wanted to be able to at least make it display a black screen at will, but I am having problems with it doing it. No matter how small the voltage that I send to it, it always shows white... My synchronization pulses are correct.

The signals are monochrome PAL standard... Basically I have the output signal that goes to 0V at synch times, and then goes to around 0.4V when its not synching. As far as I know, 0.3V is black, so it should be almost black on the TV, but its not. I don't have a schematics for it.

But my output signal is either a logical High or Low, then I attached a 1K resistor to it, and connected to the TV. The strange thing is that when I connect the signal to the TV, and attach the scope to it to see whats going into the TV, the signals are OK but the sync no longer reaches 0V. But when I remove it from the TV, the sync goes to 0V.

What should I do ?
 

ScottWang

Joined Aug 23, 2012
7,004
One thread is enough, since you don't want to post the schematic and said that you can solve the problem by yourself then please don't post the same question again, this thread will be closed.

This was what you said in your original post --
I will solve my own simple problem again guys.
 
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