Nigel, im simply puzzled by the operation of this c-sync signal, maybe you can help me out.
This is what the signal looks like without anything connected to it:
**broken link removed**
Here is what the signal looks like directly connected to the monitor:
**broken link removed**
It's already interesting to see that the top completely flattens out at the top when its connected to the monitor, but whatever, based on what I see here it seems like the c-sync out from the source can only provide about 10mA of current since thats why the voltage is so low.
However, when I did some testing to confirm this, I wasnt getting the results I should get. Based on this I should be able to hook up a 1k resistor as the load and see the full drop on it since the current would be less than 10mA, however the drop across it is 3.18V, meaning that it can now only supply 3mA of current? That doesnt make any sense, but moving on.
When I try to line dirve the signal through the op-amp, for some reason when I connect the signal to the opamp the original signal gets slighly distorted, not visible until I turn I change the sec/div to only see one square wave and make the volts/div fill the screen, but the distortion is there. Anyhow, ignoring the signal distortion, when I hook up around 325 ohms of resistance to the ouput to get 760mV to the monitor, the signal doesnt look exactly the same as it does as when the c-sync signal is directly connected to the monitor (the second picture), and results in the monitor not syncing properly. Heres what im talking about:
**broken link removed**
As you can see, the square wave type signal isnt getting to the monitor while trying to line drive it, which is why (i think) the monitor wont sync properly when trying to drive it this way.
Any suggestions?