Electrical Circuit Operation Principles; C172 Psb/Pse Electrical Circuit Board - Epson Stylus COLOR 1520 Service Manual

EPSON Stylus &2/25 1520

2.3 Electrical Circuit Operation Principles

This printer consists of the following circuit board:
„C211 MAIN board
„C178 PSB/PSE board
„C211 Panel board
Head driver circuits (nozzle selection circuit) are directly attached to the black and color heads. Figure 2-
17 shows the block diagram of the electrical circuit.

2.3.1 C172 PSB/PSE Electrical Circuit Board

The input voltages for the PSB/PSE board are as shown in Table 2-7. Since the electrical circuit of this
printer is in a secondary circuit, it accommodates the delay timer to make the printer execute the capping
operation even though the printer is turned off during the operation. With this function, the printer can
prevent the ink clogging or smudging caused by the exposed printhead.
The electrical circuit 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 circuit, converting into DC voltage. This DC voltage is then input to the switching circuit.
Along with this switching operation by FET on the primary side, +42 voltage is generated and stabilized on
the secondary side. The produced +42 voltage is then converted into the stable +5 VDC by the regulator
IC. The CPU on the C211 MAIN board monitors the on/off signal of the power switch on the control panel.
When the power goes off, the CPU sends the Power Off signal (PSC) to the electrical circuit. The
electrical board has a delay circuit (ZD86, C82 and Q84) to delay the power off. The electrolytic capacitor,
which control 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 minimum 20
seconds, which depends on the capacitor size.)
2-16
Figure 2-17. Electrical Circuit Block Diagram
Table 2-7. DC Voltage Distribution
VDC
‰ CR motor/PF motorMotors
+42 V
‰ Printhead common voltage
‰ C211 MAIN control board (logic)
+5 V
‰ Sensors (HP sensor, PE sensor, ink cartridge
sensor, DE sensor, cover open sensor)
‰ Control panel, Head nozzle selection
Application
Rev. A