116 Theory of operation ENWW
Figure 5-8 Developing motor control circuit
The DC controller judges the developing motor faulty under the following conditions and sends an
error message to the formatter:
● Developing motor start abnormality: The interval of the /DRMITBFG signals does not
become regular in 1000 ms from the start of the developing motor.
● Developing motor rotation abnormality: The interval of the /YMCDEVFG signal stays
irregular for 100 ms or more after it has become regular.
Fan control
The fan control controls the drive of the fan.
The fan, a DC brushless motor with a built-in Hall effect device, exhausts air to prevent the
temperature from rising around the fuser unit. The fan operates under the control of the FAN
DRIVE signal (/FAND) the DC controller.
Figure 5-9 Fan control circuit
The DC controller monitors the FAN ROTATION DETECTION signal (/FANS) to control the RPM
of the fan. The /FANS signal outputs (turn “L”) when the fan rotates at the speed of the specified
RPM: when the DC controller judges the fan normal. The DC controller judges the fan faulty and
sends the error message to the formatter when the /FANS signal has not been input (turns “H”) for
10 seconds or more.
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