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7. MS Operation
When the FF or REW button is pressed with
the MS button ON, tape transport is stopped at the
blank portion of tape between tunes, and then
recommenced in play mode. When the FF button
is pressed with the MS button ON, IC401 pin 24
(PINCH SOL) is changed to "H" Ievel for 312ms.
The pinch solenoid is thereby activated and the
head base starts to rise. Pin 23 (MS SOL) of IC401
is changed to
((H"
level 260ms after the FF button
is pressed, resulting in Q504 being turned on and
the MS solenoid being activated. Following com-
pletion of the "power assist" operation, the head
base is thus moved to the MS position. The FF
solenoid is activated 416ms after the FF button is
pressed, resulting in fast forward tape travel.
During this action, a fast forward playback signal
is applied to pin L3 (SIGNAL IN) of IC401, and
if this signal is interrupted for about 84ms (cor-
responding to a portion of blank tape between
tunes) IC401 switches to playback mode auto-
matically. The above operation is much the same
when the REW button is pressed instead of the
FF button.
8. Auto-stop Mode
A photo-interrupter output is applied to pin
16 (END PULSE) of IC401 during tape transport,
resulting in the capacitor connected to pin L7
(C408) being charged up and discharged repeated-
ly. The potential at pin 17 is thus kept below the
threshold voltage, and prevents activation of the
auto-stop mechanism.
When tape travel stops and the take-up reel stops
turning, the photo-interrupter output is no longer
applied to pin 16, and the potential on the ca-
pacitor connected to pin 17 (C408) continues to
increase until it exceeds the threshold voltage.
The IC is thus switched to stop mode, thereby
stopping tape mechanisms.
F i g . 6 - 1 3 T a p e t r a v e l d e t e c t i o n
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F i g . 6 -1 2 MS o perat ion
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;
FF SOL.
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