7.6 FUSING TEMPERATURE CONTROL
(° C ) 200 180 165 150
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50
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A193D525.wmf
When the main switch turns on, the CPU checks the ac frequency for 500 ms. Then the CPU turns on the fusing lamp. When the thermistor detects the stand-by temperature (165 °C), the machine can start to print. When the thermistor detects the operating fusing temperature (180 °C), the CPU maintains this temperature using phase control. Phase control is the only type of fusing control in this machine.
7.7 OVERHEAT PROTECTION
If the hot roller temperature becomes greater than 230°C, the CPU cuts off the power to the fusing lamp. At this time, SC543 will be generated. Even if the thermistor overheat protection fails, there is a thermofuse in series with the common ground line of the fusing lamp. If the temperature of the thermofuse reaches 169°C, the thermofuse opens, removing power from the fusing lamp. At this time, the copier stops operating.
