Epson 810, 820, 830 2.2.1.2 C482 PSH board

EPSON Stylus PHOTO 810/820/830 Revision B

2.2.1.2 C482 PSH board

	+42VDC		+5VDC Signal from						PSC Signal from
									Main board
			Main baord			ZD53
					+5VDC Line
					Over Voltage
					Limitation
						ZD52,87
				+42VDC Line
				Over Voltage			ZD90
				Limitation
								+42VDC Line
								Drop Limitation
		R91,R92,R93,Q91,ZD51
			+42VDC Line
			Constant
			Control
			C51
			Smoothing						PC1
			Circuit
D51										Photo Coupler

	TRANS(T1)
	C11		Q1			Q2,Q3,Q31
	Smoothing		Main Switching				Abnormally Feed
	Circuit		Circuit				back circuit
	Over Current	Filter Circuit			Full Wave
	Protection				Rectifier circuit
F1,TH1		R1,L1,C1		DB1

AC Input

1.Regardless of the state of the power switch (On or OFF), the voltage is always applied to the primary side of the power supply board from the moment or at the state that AC-plug is plugged in. At this time, F1 plays a role of preventing AC250V from coming into the F1.

L1 also prevents high harmonic wave noise generated in the RC circuit filter which consists of C1 from going out, and eliminates the noise from outside here.

2. The AC is full-wave rectified by the diode bridge DB1, and converted to 2 x AC in voltage by the smoothing electrolytic capacitor C11.

3.The pressured up direct current turns Q1 on through the starting resistor R18, R28, R17 & R19 and starts the primary side of the circuit.

4.When the primary side is On, the energy (current) led by the electromagnetic induction through the trans (T1) does not flow to the secondary side since the diode (D51) on the secondary side is installed in the opposite direction.

5.When the energy which is charged in the trans is reaching the saturated state, the voltage which makes Q1 on becomes weak gradually. At the point that this voltage drops at the certain voltage, C13 absorbs the current in the opposite direction and Q1 is quickly shut off by the resulting sharp drop.

6.When the primary side is turned off, the energy charged in the T1 is opened according to the diode (D51) direction which is installed on the secondary side. Basically, 42 V DC is output by these circuit operations and the number of T1 spiral coil.

*Unlike the Stylus Photo 810/820, IC51 which generates +5VDC is not on the C482 PSH board for the Stylus Photo 820/830. +5VDC is generated on the C483/C484 Main-B board.

The C482 PSH board has the various control circuits to stop voltage output if a malfunction occurs on the power supply board or the main board or while the printer mechanism is on duty. Following explains each control and protection circuit.

†+42V line constant voltage control circuit :

The output voltage level of the +42V line is monitored by R91, R92, R93, Q91 and ZD51. When +42V line reaches about +42.8V, PC1 starts the operation via Q91. Consequently, FET Q1 switching operation is controlled by this circuit to stabilize the +42V line.

Operating Principles Electrical Circuit Operating Principles 45