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pressure wheel lever disengages the pressure wheel
from the capstan. To allow remote control of rewind-
ing, the F models are not equipped with a tape brake.
When there is no current through the start/stop sole-
noid, the pressure of the start/stop lever against the
pressure wheel lever is released, and the tension of
the pressure wheel spring will force the pressure
wheel against the capstan, providing normal forward
motion. The start/stop solenoid also controls a micro-
switch for connection/disconnection of operating
voltage to terminal 19 on board no. 15001. Wiring of
this switch has been modified from serial no.
2 510 020. (Se paragraph 8.2.1).
The Brake Solenoid
The brake solenoid controls a brake located under-
neath the right hand turntable.
When current passes through the brake solenoid,
the brake is pressed against the turntable, prevent-
ing rotation.
When the current to the brake solenoid is switched
off, the brake is released and normal winding takes
place.
The Rewind Solenoid
The rewind solenoid controls both the clutch mecha-
nism and the pressure pad arm. When current is
passed through the rewind solenoid, the pressure
pad is disengaged from the erase head, and the
clutches are set for fast rewind.
The rewind solenoid also controls the microswitches
II and III, which in turn control the start/stop solenoid
and brake solenoid respectively.
7.3.2 Electrical Operation
The following explanation of the main operating mo-
des is referred to schematic.
When the current is switched on and the tape motion
lever set to position
microswitch I is activated to
provide current to the remote control mechanism.
Stop (Pedal unoperated)
Current passes through the start/stop solenoid, the
brake solenoid and to earth. The start/stop solenoid
keeps the pressure wheel disengaged from the cap-
stan, and the brake solenoid forces the brake pad
against the right hand turntable. Forward motion is
thereby stopped. The start/stop solenoid also acti-
vates a switch that disconnects the supply voltage
from terminal 19 on board on 15 001 causing the
oscillator to stop.
Note: From serial no. 2 510 020 the wiring of the
microswitch has been altered. (See paragraph 8.2.1).
Simultaneously a new switch is connected in series
with wire from potentiometer VOLUME to the input
of the output amplifier (see paragraph 8.2.2).
Rewind (rear part of pedal
depressed)
Capacitor C504 (4 [LF) is charged in the stop position.
Current now passes through the rewind solenoid and
to earth through microswitch II. The resulting power
shock (approx. 0.6 A) is absorbed by the discharge
of C501 (80 [IF). C501 is charged when the tape re-
corder is switched on. It then acts as a reserve for
the rewind power shock. When the rewind solenoid
is actuated, microswitches II and III operate. During
the transition time for switch II, current through the
rewind solenoid is maintained by C503 (8 p,F) being
charged. C504 (411F) supplies current to the start/
stop solenoid and the brake solenoid during switch-
over so that the pressure wheel is kept disengaged
from the capstan, and the brake pad is pressed
against the right hand turntable. The tape motion is
then stopped. When switches II and III are switched
over, the current passes through the rewind solenoid,
the start/stop solenoid and switch III (the brake sole-
noid is short-circuited) and to ground. The rewind
solenoid and start/stop solenoid are connected in
series, thereby limiting the current to a magnitude
within the capability of the rectifier and which is suf-
ficient to hold the solenoid activated. The clutch as-
semblies are thereby set for fast rewind, and supply
voltage for the oscillator is disconnected. (See para-
graph 8.2.1). Unwanted erasure 'of the tape in
RECORD position is thereby avoided and noise is
eliminated in the PLAYBACK position (the tape tou-
ches the heads during rewinding).
To stop rewinding, the pedal is released. The current
passes through the start/stop solenoid and the brake
solenoid. For quick retardation C502, (401.1.F) is dis-
charged through the brake solenoid. (C502 is char-
ged during rewind).
Start (front part of pedal depressed)
The current to all solenoids is switched off. The pres-
sure wheel spring forces the pressure wheel against
the capstan, the brake pad is released from the right
hand turntable, and normal forward tape motion
starts. As no current passes through the start/stop
solenoid, the supply voltage to board no 15 001 is
switched on, (see paragraph 8.2.1 on modification
from serial no 2 510 020).
The diode BY 112 prevents C502 (40 µF) from being
charged in the stop position. C502 would otherwise
discharge through the brake solenoid in the start
position, and this would result in the brake pad being
held against the take-up turntable for a period of
time after the capstan had started the tape motion.
This would result in loop formation. Capacitors C501,
C502, C503 and C504 are all located in the same can.
31
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