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

EPSON Stylus &2/25 1520

2.3.2.1 Reset Circuits

The C211 MAIN board contains two reset circuits: logic line (+5 ) and power (+42 ) line. Reset IC
M51955BFP (IC4) monitors the +42
the power line for the motors when the voltage level drops below 33.2 V. Reset IC RST592D (IC1)
monitors the +5 V line and sends low pulse when the voltage level drops below 42 V. During the printer
power on, it outputs LOW until stabilized +5 V is produced to ensure the CPU's proper operation.

2.3.2.2 Sensor Circuits

This printer has 9 sensors to monitor the printer condition.
‰HP Sensor (Home position sensor)
The HP sensor for this printer 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 interrupted system is highly reliable because it has no contact with any mechanism.
‰PE_R sensor (Rear Paper End sensor)
The PE_R sensor, attached to the rear side of the paper path, detects the paper presence condition
for continuous paper or cut sheet set in the rear side of the paper path. A mechanical switch used for
this sensor opens when paper is fed and closes without any paper detected.
‰PE_F sensor (Front Paper End sensor)
This PE_F sensor, located in the paper guide unit, detects cut sheet presence condition in ASF. This
sensor uses a mechanical switch which opens when paper is detected and closes with no paper
detected.
‰REL sensor (Release sensor)
REL sensor is built into the rear part of the left frame in the printer mechanism. It determines whether
the release lever is set to the cut sheet side (friction mode) or continuous paper side (tractor mode). A
mechanical switch used for this sensor opens and closes when the lever is set for the friction mode
and for the tractor mode, respectively.
‰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.
‰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
line. It outputs /NMI signal to the CPU and the gate array to cut off
Figure 2-20. Reset Circuit Block Diagram
Rev. A