Read Sharp AR-M165-207 (serv.man17) Service Manual online
AR-M207 M165 M162 ELECTRICAL SECTION 13-5
[High temperature protect circuit in case of CPU hung up]
For IC23 3pin (reference voltage), +3.3V is divided by the resistor.
The thermistor terminal voltage is inputted to IC23 2pin.
The thermistor terminal voltage is inputted to IC23 2pin.
When, the voltage at 2pin becomes lower than the voltage at 3pin (when
the heat roller temperature is about 220 - 230°C), IC23 1pin becomes
HIGH, and the HL signal is lowered to the GND potential through IC22,
HIGH, and the HL signal is lowered to the GND potential through IC22,
stopping generation of the heater lamp ON signal. (IC23 1pin is normal
LOW.)
[When the heat roller surface temperature is lower than the set level]
1) Since the thermistor terminal voltage is higher than the set level, the
HL signal from the CPU becomes HIGH.
2) The HL signal is turned to be the HLOUT signal through IC22 protect
circuit, and inputted to the photo triac coupler on the power PWB.
3) When the internal triac turns on, a pulse is applied to the gate of the
external triac. Consequently a current flow from the power source
through the heater lamp to the triac, lighting the heater lamp.
[When the heat roller surface temperature is higher than the set level]
1) Since the thermistor terminal voltage becomes lower than the set
value, the HL signal from the CPU becomes LOW.
2) The HL turns LOW, the photo triac coupler on the power PWB turns
OFF, the external triac turns OFF, and the heater lamp turns OFF.
[In case of the thermistor open]
The voltage at IC23 6pin over the voltage at 5pin to drive the output
THOPEN at 7pin to LOW. This is passed to the CPU and the trouble
THOPEN at 7pin to LOW. This is passed to the CPU and the trouble
code "H2" is displayed.
(6) Driver circuit (Solenoid)
a. Outline
Since the load signal from the CPU or the ASIC cannot drive the load
directly, it is passed through the driver IC to drive the load.
b. Operation
The driver circuit forms a Darlington circuit with transistors. Therefore a
large drive current is obtained from a small current (ASIC output current).
When the driver input voltage (base resistance input) is HIGH (+3.3V),
When the driver input voltage (base resistance input) is HIGH (+3.3V),
the transistor turns ON to flow a current in the arrow direction, operating
the load. When the driver is ON, the driver output terminal voltage is 0V.
(7) Toner supply motor drive circuit
The IC34 is the motor control IC, which generates the pseudo AC
waveform with the pulse signals (TM, TM-) outputted from ASIC, driving
the toner supply motor.
the toner supply motor.
(8) Main motor drive circuit
The main motor is driven by the MMD signal from ASIC. While the main
motor is rotating, the MMD signal is driven to HIGH and passed through
IC26 to the control circuit in the main motor to rotate the main motor.
When the main motor speed reaches the specified rpm, the MMLD
When the main motor speed reaches the specified rpm, the MMLD
signal is turned LOW and passed through IC115 to the CPU.
LOAD
+24V
ASIC/CPU
OUT PUT
LOAD
(TM_)
(TM)
TMA_O
TMB_O
5VEN
24V
C155
0.1u
R132
47KJ
R133
47KJ
IC34
TA7291AS
2
9
1
5
3
7
8
6
4
VDD
IN1
IN2
VSS
OUT2
OUT1
VCC2
VCC1
N.C
+
C154
10u/35V
10u/35V
CP3
0603FA1.5A
MMLD
ASIC
Main Motor
Control
Circuit
( Main Motor)
IC26
TD62503F
I1
1
O1
16
I2
2
O2
15
I3
3
I4
4
O3
14
I5
5
O4
13
I6
6
O5
12
I7
7
COM
8
O6
11
O7
10
NC
9
MMD
MMD
/MMD
CPU
[13]ELECTRICALSECTION.fm 5 ページ ２００４年１１月１２日 金曜日 午後２時２１分
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