Advertisement
|
MK-100
Technical Information
1. Stand-by mechanism
When the unit is not loaded with a cassette, the slide contro! knob (3) is immovable since the pin (1) is engaged within the
cam
(2). Loading a cassette properly depresses the thrust pin (4) which in turn releases pin (5) permitting the head base (6) to
move forward so the head can make contact with the tape.
However, the tape is not transportable in this mode since the pinch roller and the capstan (9) are not making actual contact
because the S. S. plate (7) is holding back the pinch roller arm (8). This is to say that the stand-by mode is now in effect.
Pushing the slide control knob up towards the PLAY position, will commence running of the tape.
When
the cassette
is being ejected, the pressing of the eject button pushes backward the head base and pin (4) is pressed
inwards
by the spring (10) and the head base automatically
returns to its original position. Continuing to press the eject
button in this manner will raise the eject lever (11) and permit the cassette to be withdrawn. Press to lock the REC button
and push the slide control knob up towards the PLAY/REC position to start the tape.
Then the tape will start running for recording.
Pushing the slide control knob down towards the STOP position only stops the tape transport leaving the record button in its
locked position.
This is the same as a conventional pause mode.
In order to release the REC button, push the slide control knob down towards the REW/REC OFF position or press the eject
button. Pressing the REC button during playback, can change the playback mode directly into the recording mode.
Fig. 19
2. Circuit for auto-stop and tape-end warning
This recorder is equipped with a mechanism
in which the motor automatically stops and a warning signal becomes audible
from the speaker soon after the tape reaches to its end in any mode. The tape-end is automatically detected by the take-up
disc signalling the tape's completion.
A reflection plate alternately colored silver and black as shown
in illustration is placed on the under surface of the take-up
disc. After the power is turned on, the LED
(D15) lights and illuminates this reflecting plate. The photo transistor X11
is
placed to the side of the LED and the impedance across its collector and emitter varies in proportion to the amount of
reflection from the reflecting plate, thus varying its collector voltage. When
the reel disc stops, the amount of reflection
ceases to vary and likewise the collector voltage at X11 will become stable.
X12
is a switching transistor and is biased to be turned on by the charging current which flows to C36 through R51 when the
collector voltage at X11
increases in the positive direction from 0. Therefore, while the take-up disc is rotating, X12 con-
tinues to be turned on and off alternately. When the take-up disc ceases to rotate, X12 comes to be turned off.
On the other hand, after the power is turned on, X14 is biased and turned on through R56 and the motor starts rotating since
the negative pole in the motor governor is earthed. At the same time, C37 is charged through R54 and its voltage across
terminals tends to increase gradually.
—_9_—
No. 0002
Advertisement
