Electrical Circuit Operating Principles; C378Psb/Pse Board; Electrical Circuit - Epson Stylus PHOTO 890 Service Manual

EPSON Stylus Photo 890/1280/1290

2.2 Electrical Circuit Operating Principles

The electric circuit of the Stylus Photo 890/1290 consists of the following:
o
Control circuit board: C393MAIN/C393MAIN-B/C393MAIN-C
o
Power supply board: C378PSB/PSE
o
Panel board: C393PNL
Refer to Figure 2-11 for the major connection of the boards and their roles.
C393PNL Panel Board
C393PNL Panel Board
C393MAIN / C393MAIN-B/ C393MAIN / C393MAIN-B/
C393MAIN-C Control Board
C393MAIN-C Control Board
3.3V Regulator
3.3V Regulator
+42VDC
Power OFF
+5VDC
C378PSB/PSE Power C378PSB/PSE Power
Supply Board Supply Board
Figure 2-11. Electric Circuit of Stylus COLOR 890/1290
OPERATING PRINCIPLES
Printer Mechanism Printer Mechanism
CR Motor
PF Motor
ASF/Pump Motor
Head Driver Circuit
Sensors
Electrical Circuit Operating Principles

2.2.1 C378PSB/PSE Board

The power supply board for the Stylus Photo 890 and Stylus Photo 1290 is C378PSB/
PSE. It uses a RCC switching regulator system, and supplies +42VDC and +5VDC to
the printer mechanism and control board.

2.2.1.1 Electrical Circuit

The table below shows the voltages produced in this circuit and their applications.
Table 2-12. Application of the DC Voltages
Table 2-13.
Voltage
• CR Motor
+42VDC ± 2VDC • ASF/Pump Motor
• PF Motor
• Head driving power supply
• Logic sensor circuit
+5VDC ± 0.25VDC • Panel LED
• Nozzle selection circuit (on the printhead)
• I/F control circuit
NOTE: The 5VDC is only applied to the parts and locations shown in the table above.
The C393MAIN uses 3.3V drive chips for most of the logic-line chips (CPU,
ASIC, ROM, DRAM). For this reason, those chips are not driven by the +5VDC
produced by the but power supply board but the 3.3VDC that is reduced by the
3.3VDC regulator on the C378PSB/PSE.
Revision C
Application
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