In replay mode, head to pick up a tape video track signal, after IC5001 signal processing and amplifying the output from (5) feet envelope signal of the radio frequency (RF) ENV to IC3001 (37), after internal envelope detection circuit from the output dc voltage control (17) feet. If head congestion, IC3001 (17) feet of the output envelope signal level is lower than 25 MVP - p, its output dc voltage is less than 1 v, this was sent to control dc voltage control system microprocessor IC6004 (104), the microprocessor to detect the magnetic head congestion, by s.C (LK) and (57) the feet (55) foot (s.d. ATA) will head congestion serial data sent to the character generator IC6002 (1), (3) feet, IC6002 (12) foot print head jam alarm "X" character to the electronic video display and flashing. pV4service manual download site
 pV4service manual download site
 pV4service manual download site
In video mode, when press the start/stop button, the video camera in the way into the record for a short time before the replay, make main shaft servo stability. During this period, if the video head the clogging, IC6004 monitoring to the rf signal level drops, IC6002 (12) foot will output "X" head jam alarm character to find like electronic display and flashing. pV4service manual download site
 pV4service manual download site
The clogging envelope signal of the radio frequency can detect whether a video head, also can be achieved by measuring the size of the envelope signal output video track automatic tracking. At the same time press operation panel on the track "+ / -" button, the main axis servo system into automatic tracking mode, video IC5001 head amplifier (5) feet output envelope of the radio frequency signals to IC3001 (37), after the envelope detector into a dc voltage from IC3001 (19) feet and sent to the system output control and servo IC6004 (43), internal dominated by IC6004 axis servo circuit dc voltage error. The dc voltage error by IC6004 output (93) foot, sent to the main shaft motor driver IC IC2103 (16), the main shaft motor speed adjustment, make IC5001 (5) feet output envelope of the radio frequency signals to the maximum, which means that track to track the location for the best.

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