Fuser-control circuit The fuser-control circuit monitors and controls the temperature in the fuser. The product uses on- demand fusing. The fuser-control circuit consists of the following major components: ● Fuser main heater (H1): heats the center of the fuser sleeve ● Fuser sub heater (H2): heats the ends of the fuser sleeve ● Thermistors; detects the fuser temperature (contact type) ◦ Sleeve thermistor (TH1): Detects the temperature at the center of the fuser sleeve ◦ Main thermistor (TH2): Detects the temperature at the center of the fuser heater ◦ Sub thermistor 1 (TH3): Detects the temperature at the end of the fuser heater nearest the front of the product ◦ Sub thermistor 2 (TH4):
Detects the temperature at the end of the fuser heater nearest the rear of the product ● Thermal fuse (FU1): prevents abnormal temperature rise in the fuser heater (non-contact type) Figure 1-6 Fuser-control circuit TH3 Pressure roller TH1 Front of engine TH2 FU1 H1 Low-voltage power supply H2 Fuser heater control circuit TH4 FUSER HEATER CONTROL signal DC controller FUSER TEMPERATURE signal Fuser heater safety circuit Fuser sleeve 14 Chapter 1 Theory of operation ENWW