Read Sharp MX-PNX1C (serv.man12) Service Manual online
MX-FNX1/MX-PNX1 ELECTRICAL SECTION 10 – 8
g. Rush current limit circuit
This circuit limits a rush current flowing through the current-regen-
erating capacitor in the motor drive system to a certain level. It is
composed of the posister (PTH2) which limits a current and the
FET (Q3) which flows a current in the steady state.
From when the front cover switch (FDSW) is closed to when the
cathode voltage of ZD1 reaches the zener voltage by the time con-
stant of R42 and C14, the base current is not supplied to Q1, turn-
ing OFF Q1 and Q3. During this period, a current flows through
PTH2 to charge the current regenerating capacitor.
After the current regenerating capacitor is fully charged, when the
cathode voltage of ZD1 exceeds the zener voltage by the time con-
stant of R42 and C14, the base current is supplied to Q1 to turn ON
Q1 and Q3. The current flowing through PTH2 flows through Q3,
releasing the current limit operation.
The circuit composed of PTH1 and D1 immediately removes elec-
tric charges accumulated in C14 when the front cover switch
(FDSW) is opened. This circuit allows the rush current limit opera-
tion for instantaneous open/close of the cover.
erating capacitor in the motor drive system to a certain level. It is
composed of the posister (PTH2) which limits a current and the
FET (Q3) which flows a current in the steady state.
From when the front cover switch (FDSW) is closed to when the
cathode voltage of ZD1 reaches the zener voltage by the time con-
stant of R42 and C14, the base current is not supplied to Q1, turn-
ing OFF Q1 and Q3. During this period, a current flows through
PTH2 to charge the current regenerating capacitor.
After the current regenerating capacitor is fully charged, when the
cathode voltage of ZD1 exceeds the zener voltage by the time con-
stant of R42 and C14, the base current is supplied to Q1 to turn ON
Q1 and Q3. The current flowing through PTH2 flows through Q3,
releasing the current limit operation.
The circuit composed of PTH1 and D1 immediately removes elec-
tric charges accumulated in C14 when the front cover switch
(FDSW) is opened. This circuit allows the rush current limit opera-
tion for instantaneous open/close of the cover.
B. MX-PNX1A/B/C/D
(1) General
This circuit controls the punch function of paper discharged from
the main unit.
It is composed of circuits which process signals from sensors and
the inner finisher and the circuit which drives the motors.
the main unit.
It is composed of circuits which process signals from sensors and
the inner finisher and the circuit which drives the motors.
(2) Circuit descriptions
a. Sensor input circuit
1)
Full sensor (FPDD)
The full sensor (FPDD) employs the photo interrupter in which
the light emitting diode and the photo transistor are integrated.
The full state is detected by interruption of lights with the light-
shielding plate. By use of Q8, the logic when the connector is
disconnected is made the same as when light is emitted to the
sensor (full).
Signals are inputted through the noise filter of R10 and C2 to
the multiplexer (IC9-4pin).
The logic of a signal inputted to the CPU on the inner finisher
circuit is fixed to H when the punch dust container is full.
R2 is the current limit resistor of the light emitting diode, and
R6 is the load resistor of the sensor.
The full sensor (FPDD) employs the photo interrupter in which
the light emitting diode and the photo transistor are integrated.
The full state is detected by interruption of lights with the light-
shielding plate. By use of Q8, the logic when the connector is
disconnected is made the same as when light is emitted to the
sensor (full).
Signals are inputted through the noise filter of R10 and C2 to
the multiplexer (IC9-4pin).
The logic of a signal inputted to the CPU on the inner finisher
circuit is fixed to H when the punch dust container is full.
R2 is the current limit resistor of the light emitting diode, and
R6 is the load resistor of the sensor.
2)
Punch position sensor (FPHPD)
The punch position sensor (FPHPD) employs the photo inter-
rupter in which the light emitting diode and the photo transistor
are integrated.
The full state is detected by interruption of lights with the light-
shielding plate. By use of Q9, the logic when the connector is
disconnected is made the same as when light is emitted to the
sensor (when punching).
Signals are inputted through the noise filter of RA11.2 and C55
in the inner finisher circuit to the CPU (IC10-87pin).
The logic of a signal inputted to the CPU is fixed to H at the
home position, and L when punching.
R1 is the current limit resistor of the light emitting diode, and
R97 (in the inner finisher circuit) is the load resistor of the sen-
sor.
The punch position sensor (FPHPD) employs the photo inter-
rupter in which the light emitting diode and the photo transistor
are integrated.
The full state is detected by interruption of lights with the light-
shielding plate. By use of Q9, the logic when the connector is
disconnected is made the same as when light is emitted to the
sensor (when punching).
Signals are inputted through the noise filter of RA11.2 and C55
in the inner finisher circuit to the CPU (IC10-87pin).
The logic of a signal inputted to the CPU is fixed to H at the
home position, and L when punching.
R1 is the current limit resistor of the light emitting diode, and
R97 (in the inner finisher circuit) is the load resistor of the sen-
sor.
3)
Rear position sensor (FPRPD)
The rear position sensor (FPRPD) employs the photo inter-
rupter in which the light emitting diode and the photo transistor
are integrated.
The rear position is detected by interruption of lights with the
light-shielding plate.
Signals are inputted through the noise filter of RA11.3 and C56
in the inner finisher circuit to the CPU (IC10-16pin). The logic
of a signal inputted to the CPU is H when light is shielded and
L when light is emitted to the sensor.
R4 is the current limit resistor of the light emitting diode, and
R98 (in the inner finisher circuit) is the load resistor of the sen-
sor.
The rear position sensor (FPRPD) employs the photo inter-
rupter in which the light emitting diode and the photo transistor
are integrated.
The rear position is detected by interruption of lights with the
light-shielding plate.
Signals are inputted through the noise filter of RA11.3 and C56
in the inner finisher circuit to the CPU (IC10-16pin). The logic
of a signal inputted to the CPU is H when light is shielded and
L when light is emitted to the sensor.
R4 is the current limit resistor of the light emitting diode, and
R98 (in the inner finisher circuit) is the load resistor of the sen-
sor.
4)
Horizontal shift HP sensor (FPSHPD)
The horizontal shift HP sensor (FPSHPD) employs the photo
interrupter in which the light emitting diode and the photo tran-
sistor are integrated.
The home position is detected by interruption of lights with the
light-shielding plate.
Signals are inputted through the noise filter of RA11.4 and C57
in the inner finisher circuit to the CPU (IC10-17pin). The logic
of a signal inputted to the CPU is H when light is shielded and
L when light is emitted to the sensor.
R58 is the current limit resistor of the light emitting diode, and
R99 (in the inner finisher circuit) is the load resistor of the sen-
sor.
The horizontal shift HP sensor (FPSHPD) employs the photo
interrupter in which the light emitting diode and the photo tran-
sistor are integrated.
The home position is detected by interruption of lights with the
light-shielding plate.
Signals are inputted through the noise filter of RA11.4 and C57
in the inner finisher circuit to the CPU (IC10-17pin). The logic
of a signal inputted to the CPU is H when light is shielded and
L when light is emitted to the sensor.
R58 is the current limit resistor of the light emitting diode, and
R99 (in the inner finisher circuit) is the load resistor of the sen-
sor.
Main unit
Front cover switch (FDSW)
Full sensor (FPDD)
Punch position sensor (FPHPD)
Rear position sensor (FPRPD)
Horizontal shift HP sensor (FPSHPD)
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