Lexmark 2390 003 - B/W Dot-matrix Printer Service Manual page 59

FRU
1 Head Gap Sensor
23XX-001
2 Head Gap Sensor
23XX-002
23XX-003
Action
Check the function of the head gap sensor by
moving the forms thickness lever from 6 to 7
and back while printing the Demo Page
Alt + Demo. Print speed is reset at the
beginning of each line; listen for the printer to
slow down in position 7.
Disconnect the head gap sensor from
connector CN3 on the sub logic board. Check
the resistance of the sensor while moving the
forms thickness lever. Resistance should be 0
ohms at forms thickness position 7 and infinite
at positions 1 through 6.
Check the function of the head gap sensor by
turning the power on with the Alt + Macro
buttons pressed.
• With the forms thickness lever at 1, Macro
LED 1 will light.
• With the forms thickness lever at 2 and 3,
Macro LED 2 will light.
• With the forms thickness lever at 4
through 7, Macro LED 3 will light.
Disconnect the head gap sensor asm from
connector CN3 on the sub logic board. Check
the resistance of the sensor while moving the
forms thickness lever. Resistance should be 0
ohms at position 1 and infinite at positions 2
through 7.
Disconnect the head gap sensor asm from
connector CN4 on the sub logic board. Check
the resistance of the sensor while moving the
forms thickness lever. Resistance should be 0
ohms at positions 1 through 3 and infinite at
positions 4 through 7.
Diagnostic Information 2-35