Heat Lamp Control Circuit - Panasonic KX-MB2061CXB Service Manual

6.18. Heat Lamp Control Circuit

The temperature of the fixing part of the Fuser Unit is converted to a voltage by THERMISTOR and input to IC300-D19pin. The
heat lamp is turned on/off by the HTRCTL signal (IC300-AD19pin) through the photo triac (PC2) and the triac (SCR51). And two
thermostats are set on the AC line as the safety devices.
Overheat protection circuit is provided in order to prevent the Fuser unit from overheating when CPU cannot control Fuser by
some problem.
IC504 compares Thermistor voltage and fixed voltage, which is determined by R581 and R584.
If Thermistor voltage becomes lower than this fixed voltage (this voltage corresponds to about 240 degree C), output of IC504
become "H", then Q528 turns ON, and Q500 is turned Off.
As the result, no current is supplied to Fuser lamp.
1. Control at Printing
a. After the printing signal is received, turn ON the heater.
b. After that, turn ON the motor at the Primary Stable Temperature (170°C).
c. After that, control at the Secondary Stable temperature (195°C), and feed papers.
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KX-MB2061CXB/KX-MB2061CX2/KX-MB2062CXB