Service manual

EPSON Stylus Photo 870/1270 Revision B
OPERATING PRINCIPLES Electrical Circuit Operating Principles 43
2.2 Electrical Circuit Operating Principles
The electric circuit of the Stylus Photo 870/1270 consists of the following:
"
Control circuit board: C304MAIN
"
Power supply board: C298PSB/PSE
"
Panel board: C304PNL
Refer to Figure 2-10 for the major connection of the boards and their
roles.
Figure 2-10. Electric Circuit of Stylus COLOR 860/1100
2.2.1 C298PSB/PSE Board
The power supply board for the Stylus Photo 870 and Stylus Photo 1270 is
C298PSB/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 2-7. Application of the DC Voltages
NOTE:
The 5VDC is only applied to the parts and locations shown in the
table above. The C304MAIN 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
C298PSB/PSE.
C298PSB/PSE Power
Supply Board
C298PSB/PSE Power
Supply Board
Power OFF
+5VDC
+42VDC
C304PNL Panel Board
C304PNL Panel Board
3.3V Regulator
3.3V Regulator
C304MAIN Control Board
C304MAIN Control Board
CR Motor
PF Motor
ASF/Pump Motor
Head Driver Circuit
Sensors
Printer Mechanism
Printer Mechanism
Voltage Application
+42VDC ± 2VDC
Rated output current: 0.5 A
Maximum current: 1.4 A
• CR Motor
• ASF/Pump Motor
•PF Motor
• Head driving power supply
+5VDC ± 0.25VDC
Rated output current: 0.5 A
Maximum current: 0.6 A
• Logic sensor circuit
• Panel LED
• Nozzle selection circuit (on the printhead)
• I/F control circuit
• Slave CPU for DC motor control