Sanyo PLUS Q50 Service Manual page 4

REPEAT
1. Pushing the "repeat" switch during playing permits output to
enter the monostable m ultivibrator (one-shot) circuit IC4.
The output is kept high about 10 msec long after the push of the
said switch. The output enters the IC6 by its CK (clock) terminal
(pin no. 11) to set it. Output Q of the IC6 goes then high, which
triggers the LED driver Q6 to make the^ LED D7 come on.
When playing comes to an end, output Q goes low, filling the
requirements at the nor gate IC2. As a result, the output causes
the same operation as on starting through the diode D10, result­
ing in repeat operation.
* When the "repeat" switch is pushed before start, pushing the
switch once more about two seconds later fills the requirements
at the and gate composed of diodes D13 and D14. As a result,
the output enters the "repeat" flip-flop IC6 through its CL
(clear) terminal (pin no. 11) to reset it, causing the LED D7 to
go out. If the "repeat" switch is further pushed in about two
seconds after that, the IC7 is held, and therefore, the repeat
operation is made after termination of playing.
QUARTZ LOCKING
The "quartz-lock" switch is initially set with initialization, but can
be reset with the push of that switch, enabling rotational speed
adjustment.
1. The output signal is, when the quartz-lock switch is pushed, fed
to the monostable m ultivibrator (one-shot) circuit IC4, and is
held high in about 10 msec after the push.
This output enters then the IC6 by its CK_(clock) terminal (pin
no. 3) to reset it, which raises its output Q to high and thereby
triggers the relay driver IC10 to drive the relay RL-1. Thus, the
relay terminal is put in NO (normal open) state, opening the
quatz PLL terminal and the common terminal o f main-motor
PCB. Thiscancels the lock and causes short circuit at the relay
terminal of relay RL-2, enabling the adjustment of VR1 (45
rpm) and VR2 (33 rpm).
STROBING
Turning on the "pow er" switch (S10), whenever the "p la y " switch
(S14) is closed, impresses +B voltage on the motor PCB,driving the
direct-dirve motor. A t that very instant, the 4-stage binary counter
inside the IC02 of motor PCB acts as well, and its output enters the
monostable m ultivibrator (one-shot) circuit IC9 to switch on and
off the Q11 of LED driver, flickering the D41 thru D43.
MONOSTABLE M ULTIVIBRATOR (ONE-SHOT) CIRCUIT
This circuit, a circuit responsible for producing a signal of required
pulse width by picking rise and fall edges of logical signs, produces
a positive ou tput pulse at the rise edge of input pulse when TC4001
is built in. Output pulse width is represented by tw = 0.69 CR.
The resistor shown in Fig. 1 is intended to protect a gate input of
(2) from a positive overvoltage developed at point A at the very
moment when the said m ultivibrator circuit is inversed.
The use of four 2-input gates probably ensures more stable output.
These two kinds of monostable multivibrators cannot be triggered
immediately after the output rises from semi-stable state to perfect
stable state again. They require little time lapse (recovery time)
before triggered next.
MANUAL SWITCHING WAVEFORM
MONOSTABLE MULTIVIBRATOR OUTPUT
CR Set Time
• As seen from Fig
To prevent this, switching time must be fixed at a certain time.
This serves this purpose.
- 2 -
V DD
2, the push of the switch causes chattering.
;
Threshold
Level
Fig. 2
Fig. 1