[1100 man]

Hi Richard,
The problem with the signal from a VCR is jitter in the line sync pulses. Due to their mechanical imperfections, the timing of the line sync pulses varies between the odd & even fields which are recorded sequentially by each video head.

Tv's from the dual standard era onwards had 'flywheel sync' which was designed to cope with weak or missing line sync pulses caused by weak signal. It can't cope with the rapid change in timing of the sync pulses from a VCR, so picture tearing at the top is the usual symptom.

Different TV's cope better than others and as has been said, there was usually a button specifically for the VCR. This altered the time constant of the flywheel sync circuit. Usually the highest or lowest button.

The problem is usually better when the VCR is playing one of it's own recordings. It will usually be worse with pre recorded tapes, but will have nothing to do with Macrovision which affects the AGC. Sometimes careful adjustment of the line hold (not the frame hold) can help.

Sometimes the TV needs to be modified, but this can not always be done satisfactorily. I have a PYE CT205 hybrid colour set, which despite spending many hours trying different mods to the line oscillator/ flywheel sync circuits, still won't work well with a VCR.

Hope that might help,
All the best
Nick