C172 Psb/Pse Electrical Circuit Board - Epson Stylus Color 1520 Service Manual

EPSON Stylus COLOR 1520
2.3 Circuit Operating Principles
This printer consists of the following circuit boards:
T
C211 MAIN board
T
C178 PSB/PSE board
T
C211 Panel board
Printhead driver circuits (nozzle selection circuit) are directly attached to the black and color printheads.
Figure 2-17 shows a block diagram of the electrical circuits.
C172 PSB/PSE

2.3.1 C172 PSB/PSE Electrical Circuit Board

The input voltages for the PSB/PSE board are shown in Table 2-7. Since the electrical circuit of this printer is
a secondary circuit, it uses a delay timer to make the printer execute the capping operation even after the
printer is turned off. The printer uses this function to prevent ink clogging or smudging caused by an exposed
printhead.
The electrical circuitry of this board uses the RCC (Ringing Choke Converter) switching regulator. AC
voltage is first input to the filter circuit for higher harmonics absorption and is then input to the rectification
and smoothing circuits, where it is converted into DC voltage. The DC voltage is then input to the switching
circuit. An FET on the primary side performs this switching operation then generates +42 voltage that is
stabilized on the secondary side and then converted into a stable +5 VDC by the regulator IC.
The CPU on the C211 main board monitors the on/off power signals from the control panel. When the power
goes off, the CPU sends a Power Off signal (PSC) to the electrical circuit. The electrical board has a delay
circuit (ZD86, C82 and Q84) to delay power-off. The electrolytic capacitor, which controls the delay period,
continues to output +5 V and +42 V by keeping the main circuit switch on the primary side active until all
electric charge is discharged. (The delay period is normally a minimum of 20 seconds, depending on the
capacitor size.)
2-16
C211 PNL
+5 VDC
C211 MAIN
+42 VDC
Figure 2-17. Electrical Circuit Block Diagram
Table 2-7. DC Voltage Distribution
VDC
Y
+42 V CR motor/PF motor
Y
Printhead common voltage
Y
+5 V C211 Main control board (logic)
Y
Sensors (HP sensor, PE sensor, ink cartridge
sensor, DE sensor, cover open sensor)
Y
Control panel, Nozzle head selection
M-4I60 Mechanism Unit
CR/PF Motor
CR Unit
Color Printhead Black Printhead
Driver Circuit Driver Circuit
Application