Fusing Temperature Control; Overheat Protection - Ricoh A193 Service Manual

IMAGE FUSING

7.6 FUSING TEMPERATURE CONTROL

°
( C )
200
180
165
150
100
50
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, service code, 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.
(A193)
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