Epson DFX-8500 Service Manual page 78

8. Platen Gap home position sensor


Detection form:


Logical states:
9. Ribbon jam sensor


Detection form:


Function:
10. Cover open sensor


Detection form:


Logical:
11. Printhead temperature sensor (thermistor)
This thermistor is on the printhead.
12. Head fan temperature sensor (thermistor)
This thermistor is on the printhead fan.
13. Paper width sensor


Detection form:


Output form:


Logical states:
14. Carriage motor isolation resistance sensor (monitored by port AN2 of the CPU)
To provide information about the carriage motor life, the analog port (AN2) of the CPU checks the
isolation resistance every time the printer is turned on. If the isolation resistance is equal or less than
2.2 kΩ, a carriage error is detected and the printer beeps.
15. PSB/PSE Board power off sensor (signal interface)
When the +37 VDC line voltage drops, the PSB/PSE board sends a HIGH POFF signal to the main
board.
16. Top Cover Sensor (Hall effect sensor)
When the cover is open, the printer emits a 3 beep code and the +35 V line voltage drops.
Micro mechanical switch
Home: LOW (closed)
Out of home: HIGH (open)
Photo interrupter
The main board monitors signal changes during ribbon feed.
Micro mechanical switch
Cover closed: LOW
Cover open: HIGH
Photo reflector
Emitter follower
No paper present: Standard voltage level.
Paper present: The voltage level is double the standard voltage level.
OPERATING PRINCIPLES
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