EPSON Stylus Color 600
Rev. A
2-2
0
The C206 PSB/PSE board has various control circuits to stop output if m alfunction on the power supply
board, on the main board or on the duty of printer m echanism happen. Following explains each control and
protection circuits.
1) +42V Line Constant Voltage Control Circuit:
The output level of the +42V l ine is monitored by a detection circuit consisting of seven Zener diodes.
This circuit prevents vol t age from dropping for constant output v oltage.
2)+5V Line Over voltage Protection Circuit:
This protection circuit is in the same l ine as +42V overvoltage protecti on circuit is located. The output
voltage level of t he + 5V line is monitored by a Zener diode. Thi s ci rcuit shuts down the circuit operation
forcefully when the voltage l evel exceeds +9V.
3) +42VDC Line Over voltage Circuit
This ciruit is in the same line as +5V l i ne over voltage protection ci rcuit is located. The output lev el is
monitored by two Zener diodes. If the v oltage level exceeds +48VDC, this ci r c ui t stops circuit
operation forcefully.
4) +5V Line Constant Voltage/Constant Current Control Circuit:
The output current is monitored by a +5VDC generati on switching control IC(IC51), which also
monitors the output voltage. Thi s information is input to the inter nal comparator and stabilizes+5V
line. Also, operation of the secondary side switch i s ex plained below.
1) When the power is turned on, Q1 repeats ON/OFF automatically along with the increase and
decrease of energy on the trans coil at the primary si de. While the power is being on, PSC
signal is input to the power supply board from the C200 m ai n board.
2) This signal turns Q84 on and it becomes possible to discharge energy between 8-9 of T1.
At this time, even if t he power is turned off, the electrolytic capac i tor keeps Q84 on for a while.
By this electrolytic capacitor, output i s hold at least 30 seconds even after the power is turned off.
This time helps the printer to compl et e the P-Off operation.
F1
L1,R1-R2 C1-C4
DB1 C11
Q1
T1
C84,Q84
Q2,Q3,
T
R
A
N
S
+5V generation
C51
PC1
+42VDC
+5VDC
Q31,PC1
AC100V
D51
+42V overvoltage
protection circuit
+5V overvoltage
protection circuit
Delay circuit
Power OFF
ZD52,87 ZD53
ZD81-86,
ZD51
PSO Signal
Filter Circuit
Prevention of
current flow
Rectifier circuit
Main switching
circuit
Smoothing
circuit
Feedback
circuit
Photo coupler
circuit
Smoothing
+42V constant
voltage control
(IC51)
circuit
circuit
Full Wave
Figure 2-18. C206 PSB/PSE Board Block Diagram