The SLO-1800 can either internally generate its own sync (synchronization) burst or it can be controlled externally. Almost all but the most professional VCRs control the start of the video scanning using an internally created sync signal. This in harmony with the control pulse, recorded along the bottom edge of the tape, produce the video at thirty frames per second. The pulse starts each frame and the sync burst (contained within the recorded NTSC 3.58 signal) starts each horizontal scan line that fills the screen. No sync signal, no moving scan or lines and no picture. The SLO-1800 has a switch on the back for selecting INT internal or EXT for EXT SYNC. Internal is where the VCR generates its own signal during recording. External is when a sync generator is used. It is inputted using the BNC connector on the back near the switch (see above). When set to external the recorder relies on a separate device to tell the recorder when to start each scan line. The coaxial out connector for the optional RFU-634 RF modulator is seen on the right. For more on the modulator click here. ©Misterßetamax go to homepage