Lexmark C78x Service Manual page 103

Step Actions and questions
2 Check the TMC pin (B) in the cyan cartridge contact
assembly to make sure it moves freely.
Does the pin move freely?
3 Go to the Base Sensor Test. See
TEST" on page 3-24, and check the cyan TMC
sensor. When you 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 in, 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 cracked or broken?
5
Check the mounting of the developer HVPS. Make
sure the screws that mount the power supply are
properly tightened down 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 J6 on the system board.
Is the cable properly installed?
Check the voltage at connector J6-11 on the system
8
board while pressing the cyan TMC pin in the cartridge
contact assembly.
Does the voltage change when the pin is pressed?
B
"BASE SENSOR
Yes No
Go to step 3 Replace the
cartridge contact
assembly. See
"Cartridge
contact
assembly
removal" on
page
Replace the Go to step 4
cartridge.
Go to step 6 Go to step 5
Replace the If the board is
developer HVPS incorrectly
board. See installed, install it
"Developer correctly. Make
HVPS board sure all the
removal" on mounting screws
page 4-39. are tightened
down. 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 Go to step 9
system board.
See "System
board removal"
on page 4-90.
Diagnostic information
5061
4-35.
2-59