[old_tv_nut]

I want to make sure of your terminology of a positive signal or negative signal from the VA62.

It looks to me like the polarity of the video detector diode means the signal at C1 should have negative-going sync (casually called a "positive signal"). So, a signal from the Sencore VA62 with negative-going sync should be the proper polarity, it seems.

I wonder if you are having a problem due to the AC coupling in your amplifier (even though you are inserting an average DC with the battery).

Can you check with a scope set to DC coupling or maybe just with a voltmeter whether the VA62 output runs negative from ground (like the regular C1 voltage) or floats around zero?