Lexmark 4039-1XX, Service Manual

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Diagnostic Information
25
For redrive-mounted sensor: make sure the plastic bails and guide
are in good condition and that they guide the sensor flag out of and
into the sensor as paper passes into the bin. On the sensor, the
voltage from pin 2 to pin 3 (pin 1 is the bottom pin) should change
from 0 to +5VDC as the sensor is blocked and unblocked. Pin 1
should always m5VDC.
Replace the sensor, the sensor card (on machines with latch-
mounted sensor), or the sensor cable as necessary.
Operator Panel Problem
Possible causes: failed LCD or operator panel card, cable or
connector problem, or system board problem.
Replace the operator panel if POR stops with 1½ rows of pels
displayed.
Run the diagnostic tests for the LCD and for the buttons. If only
some buttons or pels work, replace the operator panel.
If the operator panel is blank: check for +5VDC at pin 1 of the in-line
connector under the top cover, and replace the operator panel if the
voltage is good. Check for +5VDC at (10P/10R/12R/12C/12L) J7-1
(16L) J5-1 on the system board and replace the cable if the voltage
is good.
If the voltage at the system board is incorrect, check that the LVPS is
providing the correct voltages and replace the LVPS if its output
voltages are wrong.
On models 10R/12R/12C/12L, a DC-DC convertor changes
+34VDC at J9-1 into +5VDC, +12VDC, and -12VDC. Check for
+5VDC at J8-1 and for +34VDC at J9-1 and at J11-4. Replace the
DC-DC convertor, the system board, or the LVPS depending on
where the voltage is incorrect.