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25
Drum motor
[Mechanism controller: Drum error (PWM)
→
Drum driver: DRUM VS]
The drum error signal (PWM signal) that is output from IC2401 passes through a
low-pass filter (IC2503) and becomes the drum servo error signal. The drum
servo error signal is power amplified and is sent to the drum motor drive circuit
(IC2505) as the DRUM VS signal.
[Drum driver: DRUM VS
→
Drum motor]
The drum servo error voltage (DRUM VS) is input to the drum motor drive circuit
(IC2505). The drum driver circuit supplies the electric power to the U, V and W
drive coils of the drum motor that is required to rotate the drum in accordance
with the drum error voltage.
The three currents that flow through the three drum motor drive coils must be
switched in accordance with the rotary phase of the drum motor. The rotary phase
is detected by IC from the counter-electromotive force of the motor coils, so that
the three-phase switch is activated.
[Drum motor sensor circuit]
The FG signal that is picked from the drum motor is amplified and waveform-
shaped by IC2503 and sent to the mechanism controller IC2401. The DPG
signal that is generated by the drum PG coil, is amplified and waveform-shaped
by IC2401 and sent to the mechanism controller IC2401 where the DPG signal
is used as the drum speed data and the phase servo data by the mechanism con-
troller IC2401.
Capstan motor
[Mechanism controller: Capstan error (PWM)
→
Capstan driver: Cap VS]
The capstan error signal (PWM signal) that is output from IC2401 passes through
a low-pass filter (IC2504) and becomes the drum capstan error signal. The cap-
stan servo error signal is power amplified and is sent to the capstan motor drive
circuit (IC2504) as the CAP VS signal.
[Capstan driver: Cap VS
→
Capstan motor]
The capstan servo error voltage (CAP VS) is input to the capstan motor drive
circuit (IC2504). The capstan driver circuit supplies the electric power to the U, V
and W drive coils of the capstan motor that is required to rotate the capstan in
accordance with the capstan error voltage.
[Capstan motor sensor circuit]
The FG signal that is picked from the capstan motor is amplified and waveform-
shaped by IC2504 and sent to the mechanism controller IC2401. This signal is
used as the capstan speed data by the mechanism controller IC2401.
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