b. Check the specific model of recorder and its maintenance manual to
You should also determine the mode of operation, because in the record/record
standby mode, you have a vertical sync input which also controls the servo
c. In the playback mode, you have a delayed type of control track input which
determines the servo frequency.
d. Also during play/standby you have a 60Hz signal from the power supply.
e. The servo frequency is a combination of two or more frequencies (fig 1-8).
Either or both may be variable, and this combination of frequencies is used to
control the speed of the head drum motor.
Block diagram of servo signal source