C408 Pse Board - Epson Stylus Photo895 Service Manual

EPSON Stylus PHOTO 895/785EPX/915/825

2.2.1 C408 PSE board

The power supply boards of Stylus PHOTO 895/785EXP/915/825 use a RCC (Ringing
Chalk Converter) circuit, which generates +42VDC for drive line and +5VDC,
+3.3VDC for logic line to drive the printer. The application of the output voltage is
described below.
Table 2-7. Application of the DC Voltages
Voltage
• Motors (CR Motor, PF Motor, ASF motor)
+42VDC • Printhead common voltage
• Printhead nozzle selector 42V drive voltage
• C408/C498 MAIN control circuit logic
+5VDC
• Sensor
+3.3VDC • C408/C498 MAIN control circuit logic
AC voltage input from AC inlet first goes through filter circuit that removes high
frequency components and is then converted to DC voltage via the rectifier circuit and
the smoothing circuit. DC voltage is then lead to the switching circuit and FET Q1
preforms the switching operation. By the switching operation of the primary circuit,
+42VDC is generated and stabilized at the secondary circuit. This +42VDC generated
by the secondary circuit is converted to +5VDC, +3.3VDC by the chopping regulator
IC of the secondary circuit.
Operating Principles
Application
Electrical Circuit Operating Principles
ZC-RCC converter
• Over current protective
function
• Over voltage protective
function
• Secondary side SW
function with delay circuit
• Power saving mode applied
Smoothing
Circuit
D51 C51, C52
TRANS (T1)
Over Current
Filter Circuit
Protection
F1, TH1 L1, C1
AC Input
Figure 2-18. C408 PSE Board Block Diagram
The C408 PSE board has the various control circuits to stop voltage output if a
malfunction occurs on the power supply board or the main board while the printer
mechanism is on duty. Following explains each control and protection circuit.
Revision B
+42VDC
5V Chopper
+5VDC
Circuit
3.3V Chopper
+3.3VDC
Circuit
PSC signal from
Main board
saving
signal
Main Switch
Circuit
Q1
Full Wave
Smoothing
Rectifier
Circuit
Circuit
DB1 C11
45