Denon DR-M33HX - Mechanism Control Microcomputer; Outline of Mechanism Control; Auto Tuning (CTS) System

• Outline of the Mechanism Control Microcom¬
puter
The function of the microcomputer, which is applied to the
uni-directional transport cam drive control cassette deck
mechanism, will receive an outside signal from the opera¬
tion switch (operations such as PLAY, REC, STOP, FF)
during the recognition of the current condition or from the
surrounding circuits of the microcomputer (automatic tun¬
ing, linear counter, cam encoder, reel pulse, etc.) and sends
the appropriate control signal.
To the mechanism: rotational direction of the reel motor,
speed, stop, rotational direction of the cam motor, stop.
To the linear counter: makes an output of the mechanism
run mode command (REW, FF, PAUSE, PLAY).
To the automatic tuning: REC, P/B, LINE mute signal
commands. Makes an output of the BIAS ON/OFF com¬
mand (CUE command).
To the display: REC, PAUSE (REC MUTE during flash).
In addition, the following points are taken into consider¬
ation.
(1) Stable and accurate cam rotation position control is
required since a cam drive method is employed to
make the mechanism silent. Accurate rotation position
control is performed by using a cam drive with a rotary
encoder detected digital feedback servo.
(2) Since the leading time of the cam drive is slower when
compared to that of the plunger method, problems will
arise when attempting record/playback or stop at the
designated tape position from FF or REW, since tape
overrun occurs. This is especially important when
controlling the recording from the position where the
automatic tuning was completed.
(Erasing the previous music when making recordings
after the automatic tuning is completed must be
prevented.)
For this, the tape cuing is corrected after the automatic
tuning is completed to control the tape position
accurately.
(3) Power outage measures.
When the power supply is cut off, the cam of the
mechanism shifts to STOP.
(4) Overload measure s of the cam
If the cam stops an overload for any reason and
cannot shift to the target position within 4 seconds, it
is immediately shifted to STOP. If this cannot be shift¬
ed within 4 seconds, the microcomputer will stop all
controls ai'd stop the motor to prevent a breakdown.
• Auto Tuning (CTS)
This tuning system automatically sets the equalizer and
recording sensitivity, both of which are important to maxi¬
mizing the performance of various tapes and to make high
quality recordings. The tuning time is only 6 seconds;
recording chances are not missed. When the cassette is
loaded, the auto tape selector sets the deck to the standard
optimum condition. Strictly speaking, however, the record¬
ing sensitivity and frequency characteristics of the tapes
vary, depending on its type.
The auto tuning system allows the maximum perform¬
ance of the tape to be heard and at the same time ideally
corrects the frequency characteristics to a flat and wide
range characteristic.
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