Lexmark C750 Service Manual page 128

5060-00x
Step Actions and questions
3 Press the TMC pin in the cyan cartridge contact
assembly make sure it actuates the TMC switch on the
developer HVPS. When the TMC pin is pressed you
hear a click when the switch actuates. Check for
mechanical interference between the contact block and
the developer HVPS.
Note: You may need to turn the printer off to hear the
click.
Does the cyan TMC switch on the developer HVPS
board actuate properly when the TMC pin is pressed?
4 Check the developer HVPS board to make sure it is not
cracked or broken.
Is the developer HVPS board cracked or broken?
5 Check the mounting of the developer HVPS. Make sure
the screws that mount the power supply are properly
tightened and the board is positioned and mounted
correctly.
Is the developer HVPS mounted correctly?
6 Make sure the developer HVPS cable is correctly
installed on the developer board assembly.
Is the cable correctly installed?
7 Make sure the developer HVPS cable is correctly
installed at J20 on the engine board.
Is the cable properly installed?
8 Check the voltage at connector J20-9 on the engine
board while pressing the cyan TMC pin in the cartridge
contact assembly.
Does the voltage change when the pin is pressed?
9 Check the voltage at connector J20-9 when the cyan
TMC switch is pressed.
Does the voltage measure approximately +3.3 V dc?
10 Check the developer HVPS to engine board cable for
damage, broken connections, or wire and shorts
between adjacent pins.
Are there any signs of damage to the cable?
11 Disconnect the developer HVPS cable from connector
J20 on the engine board. Measure the voltage on
connector J20-9 on the engine board.
Does the voltage measure approximately 0 V dc?
2-94
Service Manual
Yes No
Replace the Go to step 4
cartridge.
Replace the Go to step 5
developer HVPS
board assembly.
Go to step 6 If the board is
incorrectly
installed, install it
correctly. Make
sure all the
mounting screws
are tightened.
Recheck the
printer to see if a
940 error is still
displayed.
Go to step 7 Correctly connect
the cable.
Go to step 8 Correctly connect
the cable.
Replace the engine Go to step 9
board assembly.
Go to step 10 Go to step 11
Replace the cable. Replace the
developer HVPS
board assembly.
Replace the engine Replace the
board assembly. developer HVPS
and developer
HVPS to engine
board cable.