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TOUCH SIMTK CHU
1-1. TAPE SLACK ELIMINATION CIRCUIT
1)
Because this deck employs a double capstan drive
system, if tape with a great deal of slack is used,
trouble with the tape tangling around the capstan
is likely to occur. Even if only slight tape slack
exists, it takes time after effecting a forward mode
to obtain proper tape tension, which results in a
continuous poor head-to-tape contact condition.
The purpose of this circuit is to prevent such
trouble by taking up tape slack prior to operation
for proper tape tension at-all times.
2) When a cassette is not loaded, TRIS assumes an
ON condition and TR16 an OFF condition. When
a cassette is loaded, cassette detection micro
switch SW6 contacts NC side (contact point), and
a charge current flows to C7. Within this charge
current period, TR15 is turned OFF and collector
voltage increases. Charge current flows to R52 and
C8 and at the end of the charge current period,
TR16 is turned ON and collector current flows.
This current passes D81, causing the take-up
motor to rotate, and at the same time passes D82,
causing the supply motor to rotate. Thus, the tape
is pulled from both directions, and any existing
slack is eliminated. This process continues until
the C7 charge current ends, at which time the
circuit returns to it’s previous state, stopping both
reel motors.
H SCHEMATIC-5 RWD MODE
1-2. PINCH ROLLER OPERATION AND
REEL MOTOR ROTATION TIMING CIRCUIT
1) If reel motor starts to rotate before the pinch
roller reaches the capstan, momentary brake
tension will be applied, causing the tape to break
or stretch. This circuit is for the purpose of elim-
inating such trouble by activating reel motor
revolutions after the pinch roller has contacted
the capstan when playback mode is effected.
2) When the deck is set to Play mode, TR23 collector
voltage is increased, TR24 is turned ON, the relay
functions, and the pinch roller plunger operates.
At the same time, as a result of an increase in
TR23 collector voltage, charge current passes R11
and D84 and flows to C4. During the period of
this flow of charge current, TRS base voltage is
lowered, and because TR5 is turned OFF, the
take-up motor does not rotate. However, at the
end of this flow of charge current, TRS base
voltage increases, TRS is turned ON, and motor
Starts to rotate.
The period of time until TRS is turned ON is
about 0.1 to 0.2 seconds.