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KX-MB2110RUW/KX-MB2130RUW/KX-MB2170RUW/KX-MB2117RUB/KX-MB2137RUB/KX-MB2177RUB
1.3.
Technical Descriptions
1.3.1.
Heat Lamp Control Circuit
Changed from the Original Service Manual section 6.16.
The temperature of the fixing part of the Fuser Unit is converted to a Voltage by THERMISTOR and input to IC300_pinC21.
The heat lamp is turned on/off by the HTRCTL signal (IC300_pinAE22) through the photo triac (PHT1) and the triac (CR1).
Two thermostats are provided on the AC line as the safety protection devices.
Overheat protection circuit is provided so as to prevent the Fuser unit from overheating when CPU cannot control Fuser by any
problem.
IC504 compares Thermistor voltage (THRMSTR0) and predetermined voltage, which is determined by 3.3V, R581 and R584.
If Therm0 voltage becomes lower than this predetermined voltage (this voltage corresponds to about 240°C), output of
IC504_pin7 becomes "H", then Q530 turns ON.
The heat lamp is turned on/off by the HTRCTL signal (IC300_pinAE22) through the photo triac (PHT1) and the triac (CR1).
Two thermostats are provided on the AC line as the safety protection devices.
Overheat protection circuit is provided so as to prevent the Fuser unit from overheating when CPU cannot control Fuser by any
problem.
IC504 compares Thermistor voltage (THRMSTR0) and predetermined voltage, which is determined by 3.3V, R581 and R584.
If Therm0 voltage becomes lower than this predetermined voltage (this voltage corresponds to about 240°C), output of
IC504_pin7 becomes "H", then Q530 turns ON.
Once Q530 turns on, IC507_pin7 keeps "H" even after the THRMSTR0 voltage becomes bigger than the voltage of IC504_pin5.
And when IC507_pin7 keeps "H", both Q500 and Q527 turn off.
As the result, once Fuser temperature exceeds 240°C (this temperature is abnormal condition), no current is supplied to Fuser lamp.
And when IC507_pin7 keeps "H", both Q500 and Q527 turn off.
As the result, once Fuser temperature exceeds 240°C (this temperature is abnormal condition), no current is supplied to Fuser lamp.
1. Heater control sequence at printing mode
a. After receiving printing data, heater turns on.
b. When heater temperature reaches to the Primary Stable Temperature (170
b. When heater temperature reaches to the Primary Stable Temperature (170
qC).
c. When heater temperature reaches to the Secondary Stable Temperature (170
qC/195qC), paper feed starts.
THERMISTOR
CN504
Main Board
10
R534
AE22
CN70
Q527
IC300
2
1
Overheat protection circuit
FUSER RELAY
IC504
C21
CN52
3.3V
6
R580
3.3V
R575
5
7
3.3V
Q500
R576
R503
Q530
R584
R579
THRM0
2
R509
3.3V
4
C507
R578
R581
C571
C572
R577
CN503
C538
DG
R536
R537
Q528
R538
R583
+24V
4
2
Low Voltage Power Board
(PSU P.C.B.)
TRIAC
CR1
PHOTO TRIAC
PHT1
CN3
HTRCTL
CN2
1
2
1
2
AC (L)
AC (N)
AC IN
AC (L)
AC (N)
THERMOSTAT2
THERMOSTAT1
HEAT LAMP
2
R582
HTRCTL
THRMSTR0
R505
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