Tracking And Carriage Servo System - Pioneer PD-7050 Service Manual

TRACKING AND CARRIAGE SERVO SYSTEM
The above figure is a block diagram of the Tracking
and Carriage Servo System (Fig. 4-3).
The capacitor connected between Pins 14 and 15 is a
time constant that functions to drop the high-range
gain when TG2 is OFF. The peak frequency of the
Tracking Phase Compensator is also in reverse pro-
portion to the value of the resistor connected to Pin
23, and its peak value is approximately 1.2 kHz in
case of 510k 12 resistance value.
TM3 or TM4 is switched ON in order to make a
tracking jump in the FWD (forward) or REV (reverse)
direction, respectively. The peak voltage to be applied
to the tracking coil at this time is determined by the
current value of TM3 or TM4 and the feedback
resistor from Pin 18; that is:
Track Jump Peak Voltage =
TM3 (TM4) current value X feedback resistance
' TRK coil DCR
value X " ~~
R52//R53
A FWD or REV carriage kick is . performed by
switching TM5 or TM6 to ON, respectively. The
peak voltage to be applied to the carriage motor at
this time is determined by the current value of TM5
or TM6 and the feedback resistor from Pin 21; that
is:
Carriage Jump Peak Voltage =
TM5 (TM6) current value X feedback resistance
value X —
R57
The current value at each SW is determined by the
value of the resistor connected to Pins 35 and 36.
When its resistance value is 120k 12, the respective
current values will be as follows:
TM3, TM4 = ±11 MA TM5, TM6 = ±22 MA
1 5