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It seems to be a circuit to generate PAL-N signal. PAL-N (mainly used in Argentina) has an NTSC-like subcarrier frequency. Used on a normal PAL tv or monitor, there will be no color at all. Changing the subcarrier frequency will effectively solve the problem.
The PAL-N and PAL-BGHI may have slight difference in the sync length, burst position and start/end of video, but there are large tolerances which will effectively make no difference at all on any tv/monitor.
Just make sure the burst frequency is set according to your tv -> otherwise, no color!
it seems that you havent understood what is the problem. It is not the colour subcarrier but sync timing. That is something absolutelly different.
As I can analyse the signal something is wrong in second field timing.
Instrument like WM700 simply reports Sync is missing.
I just could'nt find out what is vrong. When signal is connected to Tektronix Monitor it shows jittering in the top 20% of picture. When looking at the vertical sync pulses they jiter regarding the field. Some jitter is present in line synchronisation but less then in vertical interval. It seems that pll in horizontal synchronisation of monitor is reducing it a bit.
I do not have suitable oscilloscope to be able to examine problem in details.
I have a problem with the 1st PAL generator(pic16f84&MC1377). There is a burst in the output signal, but the picture is in black and white. There is no oscillation on the crystal 4.43MHz. I tried to adjust the capacitator trimer, but no result :|
Regarding subcarrier crystal you may use one of two other crystals (4.43361MHz and 8.86723MHz) together with frequency quadrupled or doubler. They are used in TV sets and probably you will find them.
Using ordinary LC oscillator instead of crystal will be satisfactory for B/W but not for colour signal.
Hi, I've built it, with MC1377,4.43361MHz quartz,added video modulator from old video.R15 at the emmiter of the output is 75 oms.Here is another pattern generator.I've used the pic part from it together with MC1377.It has more options.
have used AD725 instead of MC1377.
AD725 gives output 2V peak-peak at 75 ohm output impedance. I want it to convert it into the 1V p-p at 75 ohm output impedance.
can u help me?
I do now want to use only 5V supply