Electrical Circuits; C228 Psb Board - Epson Stylus Pro 5000 Service Manual

Stylus Pro 5000
Table 2-4. Sub Roller Driver Gear Train
Pump/ASF Sub Roller
motor direction
CW (right) Doesn't turn
rotation
CCW (left) Turns left; feeds
rotation paper

2.2 ELECTRICAL CIRCUITS

This section explains the circuitry of the Stylus Pro 5000.

C228 PSB BOARD

The Stylus Pro 5000 uses the C228 PSB board to generate the voltages
needed to operate the printer. Table 2-5 shows the voltages generated by
the C228 PSB board.
Table 2-5. Output Voltages of C228 Power Supply Board
Output Voltage
+42 V
Pump/ASF motor
PF motor



CR motor
Paper Load Solenoid



Printheads (common printhead voltage)
Fan


+5 V
C228 Main Board
Control Panel LEDs


+28 V
Comparator (generates printhead logic
voltage)
- 2 V Dot size control voltage
Figure 2-27 is a circuit block diagram of the C228 PSB board.
Cam Gear PF Support
Roller
Turns right Lowered
Turns left Raised
Supplies power to the:
Full Wave
Smoothing
Rectification
Circuit
Circuit
Switching Circuit
F1
CN1
L N
Figure 2-27. C228 PSB Board Circuit Block Diagram
Each power output line (labeled *1 through *4 in Figure 2-27) has a
protection circuit, as explained below.
*1) +5 VDC Over Voltage Protection Circuit
IC51 (L4960), outputs both +42 V and +5 V. If the primary switching
circuit suffers a short, the secondary output voltage level will gradually
increase, possibly damaging the main board or the C228 Driver Board.
Therefore, the +5 V output line is always monitored by Zener diode ZD94.
Output is stopped completely if the voltage level exceeds +9 V.
*2) +42 VDC Line Stabilization Circuits
Two stabilization circuits protect the +42 V line. The constant voltage
control circuit monitors the output level of the +42 V line using 7 Zener
diodes (ZD51 through ZD86). If output falls below +38 V or above +48 V,
the main switching FET(Q1) is shut off, stopping electromagnetic
induction on the primary side.
Chapter 2 Operating Principles
*2
+42 V
*1
+ 5 V
Drop Circuit
GND
- 2 V
*3
Drop Circuit +28 V
PSC
*4
CN 2
Delay Circuit
2-17