Dell 1600n - Multifunction Laser Printer B/W Service Manual page 168

Circuit Diagram
11.7.3 Fuser Ac Power Control
Fuser(HEAT LAMP) gets heat from AC power. The AV power controls the switch with the Triac, a semiconductor
switch. The 'ON/OFF control' is operated when the gate of the Triac is turned on/off by Phototriac (insulting part).
In other words, the AC control part is passive circuit, so it turns the heater on/off with taking signal from engine
control part.
When the 'HEATER ON' signal is turned on at engine, the LED of PC1 (Photo Triac) takes the voltage and
flashes. From the flashing light, the Triac part (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 heat lamp, and heat is occurred.
On the other hand, when the signal is off, the PC1 is off, the voltage is cut off at the gate of Triac, the Triac
becomes off, and then the heat lamp is turned off.
• Triac (THY1) feature :12A, 600V SWITCHING
• Phototriac Coupler (PC3)
> Turn On If Current : 15mA % 50mA(Design: 16mA)
> High Repetive Peak Off State Voltage : Min 600V
Service Manual
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