Reset Circuits; Sensor Circuits - Epson Stylus Color 1520 Service Manual

EPSON Stylus COLOR 1520

2.3.2.1 Reset Circuits

The C211 main board contains two reset circuits: the logic line (+5 V) and the power (+42 V) line. Reset IC
M51955BFP (IC4) monitors the +42 V line. When the voltage level drops below 33.2 V, It outputs an /NMI
signal to the CPU and the gate array to cut off the power to the motors. When the voltage level drops below
42 V, Reset IC RST592D (IC1) monitors the +5 V line and sends a LOW pulse. During printer power-on, it
outputs LOW until a stabilized +5 V is produced to ensure the CPU's proper operation.
M51955BFP
+5V
(IC4)

2.3.2.2 Sensor Circuits

This printer has 9 sensors to monitor its condition.
Y
HP Sensor (Home position sensor)
The HP sensor uses the photo interrupter system. When the CR unit is at the home position, the signal
goes LOW. A HIGH signal level indicates that the CR unit is off the home position. The photo interrupt
system is highly reliable because it has no contact with any other mechanism.
Y
PE_R sensor (Rear Paper End sensor)
The PE_R sensor, attached to the rear side of the paper path, detects paper for continuous feeding or cut
sheets set in the rear side of the paper path. A mechanical switch used for this sensor opens when paper
is fed and closes when no paper is detected.
Y
PE_F sensor (Front Paper End sensor)
The PE_F sensor, located in the paper guide unit, detects cut sheets in the ASF. This sensor uses a
mechanical switch, which opens when paper is detected, and closes when no paper is detected.
Y
REL sensor (Release sensor)
The REL sensor is built into the rear part of the left frame of the printer mechanism. It determines
whether the release lever is set to the cut sheet side (friction mode), or the continuous paper side (tractor
mode). A mechanical switch opens when the lever is set for friction mode and closes when the lever is
set for tractor mode.
Y
DE sensor (Disengage sensor)
DE sensor built into the middle frame detects the CR position. A mechanical switch used for this sensor
opens when the CR is at the pump side and it closes when the CR is at the paper feeding side.
Y
BCO sensor (Black ink cartridge sensor)
BCO sensor, attached to the black ink cartridge holder in the CR unit, detects the black ink cartridge
installation condition. A mechanical switch used for this sensor indicates Low when the cartridge is
installed and goes High when the cartridge is not installed. When the sensor detects no cartridge
condition, it resets the ink consumption counter.
2-20
OUT2
CPU
C90A02CB
NMI
OUT1
(IC7)
Figure 2-20. Reset Circuit Block Diagram
+42V
RST592D
(IC1) XRESET
VOUT
RES
GA
E05B34
(IC5)
RESET
GA
E05B33
(IC6)