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6-8-1 . Reel Rotation Check
The reel rotation is detected by the pulse from the photo
sensors which are mounted on the reel bases at the take-up
side and supply side.
This signal is input to the analogue input terminal (Pin @ for
supply side/Pin @) for take-up side).
If the reel pulse cannot be detected even when the capstan
motor is rotated, the reel rotation is judged to have stopped.
The capstan motor rotation is stopped and tape take-up
processing is carried out, and then the mechanism is then
moved to the STOP position. If a pulse is not input during
the period shown in the table below, the unit is judged to
have stopped .
T2
Fig. 6-8. Reel Rotation Detection Timing
Mode
FF, REW, FR-SEARCH
CU E, REV
Other than above
Table 6-7. Reel Detection Time and Stop Determination
Time
IC351
CXP80724
REEL T
BATTERY
2.5V
Fig. 6-9. Reel Rotation Detection, Dew Condensation and Battery Voltage Detection Circuits
Centre Level
1 50mVp-p
Detection
Stop deter-
time
mlnatlon time
6 msec
0.8 sec.
1 8 msec
1 .0 sec.
1 00 msec
3.0 sec.
DEW
(0.5%)
1 00K
1 5K
(0.5%)
S/S 5 V
1 00K
(0.5%)
1 0K
(0.5%)
1 0K
6-8-2. Dew Check
The dew sensor normally has a low value of below 20 k
but the resistance value changes to a value of 1 20 k
higher when there is dew.
The resistance value of the dew sensor is detected by the
analogue input terminal (DEW) of the main controller. The
presence of dew is concluded when the value is 0.53 V or
higher.
When there is dew, the d rum motor is stopped and keys
other than the POWER and EJECT keys will not work.
Once dew has occurred, it will take approximately 1 hour to
clear the problem.
6-8-3. Main Battery Voltage check
The voltage (BATTERY S ENS) obtained from dividing the
UNREG voltage by the resistance and the voltage (2.5 V)
obtained from dividing the S/S 5 V by the resistance are
input to the analogue input terminal of the main controller in
order to detect the main battery voltage.
MIN
These voltage values are read and processing is carried out
during a voltage drop. The threshold value used for this
processing is set as follows:
Pre-end voltage: Approx. 5.55 V
End voltage
When the battery pre-end is detected , a warning is
displayed on the viewfinder. When the voltage of the battery
drops further and the battery end is detected, the power
supply is turned off. (The time taken from pre - end to end is
approximately 1 to 5 minutes.)
r - - - - - - - - - - - - - - - -
•
MP 5 V
VREF
270K
47K
- - - - - - - - - - - -
I
- 4- 39 -
Approx. 5.45 V
REEL S ENSOR
DEW SENSOR
MECHANISM
Q
Q
or
,
I
I
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