Xerox 3300MFP Service Manual - Page 74

Theory of Operation Fuser AC Power Control AC power to the Fuser is controlled with a Triac, a semiconductor switch. The ON/OFF control is operated when the gate of the Triac is turned on/off by Phototriac (insulating part). When the 'HEATER ON' signal is turned on at engine, the LED of PC501 (Photo Triac) flashes. From the flashing light, the Triac (light receiving part) takes the voltage, and the voltage is supplied to the gate of Triac and flows into the Triac. As a result, the AC current flows in the lamp to create heat. When the signal is off, the PC501 is off, the voltage is cut off at the gate of Triac. The Triac is turned off, interrupting power to the lamp. ■ Triac (Q501) feature: 24 A-LV model/16 A-HV model, 600 V SWTCHING ■ Phototriac Coupler (PC501) ■ Turn On If Current: 15 mA ~ 50 mA (Design: 16 mA) ■ High Repetive Peak Off State Voltage: Min 600 V 2-32 Phaser 3300MFP Service Manual