Epson Stylus Color 1520 Service Manual page 64

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CCO sensor (Color ink cartridge sensor)
CCO sensor, attached to the color ink cartridge holder in the CR unit, detects if the color ink cartridge is
installed. A mechanical switch used for this sensor indicates Low with a cartridge installed and goes High
without it. When the sensor detects no cartridge condition, it resets the ink consumption counter.
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Cover open sensor
Cover open sensor, located at the right end of the printer mechanism unit, monitors the open/close status
for the printer cover. A mechanical switch for this sensor opens when the cover is closed and closes
when the cover is opened. When a cover open condition is detected, the printer sopts printing at the end
of the line and returns the CR slowly to the CR lock position. When printing is commanded, the CR is left
unlocked.
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Thermistor
Thermistor is attached onto the color head to monitor the temperatures around the head. It is operated to
avoid change in ink viscosity, which affects printing result. The signal output from the sensor is directly
transmitted to the analog port of the CPU.
Figure 2-21 shows sensor circuit block diagram.
Thermistor
Data Bus
CPU
THS C90A02CB
(IC7)
Address Bus
Figure 2-21. Sensor Circuit Block Diagram
SWA3
GA
PE_R Sensor
E05B34
(IC5)
SWA2
PE_F Sensor
SWA1 REL Sensor
SWA0 Cover Open
Sensor
SWA0
HP Sensor
GA
E05B33
(IC6)
SWA1
DE Sensor
SWC0
BCO Sensor
SWC1 CCO Sensor
Operating Principles
2-21