Ricoh FT8680 Service Manual page 31

31 July 1995
1.3.2 Drum Conditioning
When the fusing temperature reaches 160°C, the machine starts the drum
conditioning process. In this mode, all the coronas and lamps around the
drum are activated and drum sensitivity is stabilized, as in continuous copy
runs.
1.3.3 Vsg Adjustment
During drum conditioning, the ID sensor checks the bare drum's reflectivity
and calibrates the output of the ID sensor to +4 V.
1.3.4 Lamp Intensity Sensor Calibration
Main PCB
The exposure lamp intensity is monitored by the main PCB through the fiber
optics cable. A photodiode on the main PCB converts the light intensity to a
dc voltage. The main PCB sends a PWM signal with a 100% duty cycle to the
FL stabilizer and checks the monitored voltage, adjusting it to +3 V. This +3 V
is used as the light intensity standard.
PWM
FL
Stabilizer
2-7
PROCESS CONTROL
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