Tektronix Phaser 380 Service Manual page 117

The drum is driven by a closed-loop servo motor which, through a double
reduction belt drive, rotates the drum at 112.8 rpm for imaging and a constant
low speed for image transfer to paper.
Home sensor
Encoder
disk
Home
flag
Encoder
Paper
path
Servo motor
Warning: Closed-loop
Figure 5-9 The drum/transfix assembly
Warning
Keep your fingers away from the drum drive system; it uses a
closed-loop drive system. This closed-loop servo drive system is
dangerous since the motor torque increases if it senses the drum
slowing down. Fingers caught in the drum belts and gears can be
severely injured.
Temperature
sensor (~49°C)
Drum
servo drive
Theory of Operation
Transfix roller
Drum
heater
Fan
Belt drive
9661-79
Service Manual
5
5-15