Does your external monitor follow theses specs ? Can it switch between Pal and Ntsc ?
50 Ω BNC,
NTSC, 15.75 kHz, 60 Hz or PAL, 15.625 kHz, 50 Hz
MONITOR OUTPUT
Drives an external monitor with a signal that has a 15.7 KHz horizontal synchronizing rate. It can also be switched to provide an NTSC format output
which is compatible with VHS video recorders or a PAL format which is compatible with PALSECAM video recorders