Ricoh AC205 Service Manual - Page 170

Fusing Unit Ac Power Control, Triac Thy1: 12a, 600v Switching

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SMPS AND HVPS 6.4.3 FUSING UNIT AC POWER CONTROL The fusing lamp is heated via AC power and is controlled by a triac (THY1). "On/Off control" is achieved when the gate of the triac is turned on/off by a phototriac (PC1). The phototriac also acts as an insulting component. The fusing heat lamp is turned on/off when it receives a signal from the Engine Control section. The phototriac LED flashes when the "HEATER ON" signal is activated by the engine. The flashing light causes the triac to switch, and supplies a voltage to the gate of triac. As a result, AC current is then supplied to the fusing lamp, and heat is produced. On the other hand, when the signal is off, the phototriac is off. At this time, the voltage is cut at the gate of triac. In this situation, the triac is off and no heat is supplied to the fusing lamp. • Triac (THY1): 12A, 600V SWITCHING • Phototriac Coupler (PC3): 15mA ~ 50mA(Design: 16mA) B273 6-16 SM

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SMPS AND HVPS
B273
6-16
SM
6.4.3 FUSING UNIT AC POWER CONTROL
The fusing lamp is heated via AC power and is controlled by a triac (THY1).
“On/Off control” is achieved when the gate of the triac is turned on/off by a
phototriac (PC1). The phototriac also acts as an insulting component.
The fusing heat lamp is turned on/off when it receives a signal from the Engine
Control section. The phototriac LED flashes when the “HEATER ON” signal is
activated by the engine. The flashing light causes the triac to switch, and supplies a
voltage to the gate of triac. As a result, AC current is then supplied to the fusing
lamp, and heat is produced.
On the other hand, when the signal is off, the phototriac is off. At this time, the
voltage is cut at the gate of triac. In this situation, the triac is off and no heat is
supplied to the fusing lamp.
•
Triac (THY1): 12A, 600V SWITCHING
•
Phototriac Coupler (PC3): 15mA ~ 50mA(Design: 16mA)