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6-8-4. Tape End!Top Check
The centre of the cassette table is equipped with an LED
element for detecting the top and the end of the tape.
Both ends of the cassette base are also equipped with a
photo sensor. By checking which photo sensor receives the
light from the LED which travels through the transparent
section of the tape end, it can be determined which end of
the tape has been reached . When both photo sensors are
receiving light, it is determined that no tape is inserted. Light
is emitted in pulse form, and sync detection is carried out.
(Refer to Fig. 6-1 0.)
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M P 5 V
TAPE
SENSOR
PHOTO TR
(TAPE END)
M ECHANISM
_ _ __ _ __ _ _ _ __ _ __ _ _ _ _ _ __ _
6-8-5. Drum Motor Rotation Check
Rotation errors are checked inside the main controller by
the drum motor rotation pulse (DFG) which is used for the
servo.
If the rotation pulse is not detected even after 1 O seconds
have passed since the drum motor started up, the
mechanism moves to READY. The mechanism is also
moved to READY when the rotation speed during normal
operation is shifted by ± 30% or more.
At this time, keys other than the POWER and EJECT keys
will not work.
6-8-6. Capstan Motor Rotation Check
If the capstan motor rotation pulse (CFG) has not been
input for more than 3 seconds, the mechanism moves to
STOP and keys other than the POWER and EJECT keys
will not work.
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PHOTO TR
(TAPE TOP)
TEPE
LED
.... .
Fig. 6-10. Tape Top/End Detection Circuit
- 4-4 0 -
The signals from the photo sensors on both sides are input
to the analogue input terminal of IC351 (Pin @ for tape end
side/Pin @ for tape top side).
The difference in the output level from before the tape LED
illuminates and after it illuminates is checked inside the
main controller. If the difference is 0. 7 V or more, the tape is
judged to be at the tape end or tape top.
r - - - - - - - ,
03501
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6-9. ADJUSTING MODE
The adjusting mode can be selected by shorting Pin @
(GND) and Pin @ (TEST) of J1 005 on the C P1 board with a
wire.
The following alarm detection functions and power saving
standby mode transfer functions are not available when in
adjusting mode.
1 . Reel rotation detection
2. Dew detection
3. Detection of abnormal rotation of drum or capstan
4. Power off due to drop in main battery voltage
5. M echanism protection function
For further details on adjustment, refer to the section on
adjustment.
IC351
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