I have a problem with my Sony Betamax SL HF100 VCR. After starting play
mode, I can see the video for about 2-3 seconds and then get an blue
screen, while tape transport continues. When pressing Play and FF
simultanuously, the video can be seen but vanishes, when returning to
normal play mode. All this does not happen with all tapes, there are
others, that play with no problems. Is there any circuit in these old
Betamax recorders, which disables the reproduction because of i.e. poor
sync signal? Thanks for any hints to fix the problem.

Dietrich