Servo System - Teac TASCAM DA-P20 Service Manual

7. SERVO SYSTEM
Controls for tape speed, cylinder rotary frequency and tracking are very important since recording pattern
for DAT employs High-density recording system (114 MBPI*) in which the track-pitch is 13.591pm.
Especially, the tracking is controlled by.a servo system called ATF (Automatic Tracking Finding).
The servo system is PWM (Pulse Width Modulation) which is controlled by digital signals.
Cylinder drum
>. 313.591pm
Recording pattern on the tape
Tape
CYP ——> PWM output for cylinder control (phase)
CYFE ——> PWM output for cylinder control(Frequency)
CYG:
CYL
Change-over for A and B heads of cylinder (H: A head)
Cylinder rotation frequency detection
SH21 :
SH1 aa control signal. ATF functions when playback
ig |
Mixer
eet
eet
CAC Capstan rotation frequency detection
ATO ATF ON/OFF (H: OFF)
CAP PWM output for capstan control (Phase)
CAF PWM output for capstan control (Frequency)
PWM output for reel control
CPU B HD62014
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