Operator Panel Display Is Dim And Unchanging; Operator Panel Usb Cable Service Check - Lexmark C540n Service Manual

5025-2xx, 4xx

Operator panel display is dim and unchanging

Step Questions / actions
1 Turn the printer off, and remove the rear
shield. See "Top cover assembly removal"
on page 4-13.
Turn the printer on, and verify the following
values at JOPP1 on the controller board:
Pin
Are all these values approximately correct?
Check for continuity in the operator panel
2
cable connector.
Note: Remove the three screws holding the
operator panel, and place it facedown on top of
the printer. The cable connector pins will be
exposed and easier to contact.
Do all the conductors indicate continuity?

Operator panel USB cable service check

Step
1 Check the operator panel USB cable for
continuity.
Is there continuity?
2-38
Service Manual
JOPP1
Value
1 0 V dc
2 +5 V dc
3 0 V dc
4 Ground
5 +5 V dc
6 +3.3 V dc
7 Ground
Questions / actions
Yes
Go to step 2.
Replace the operator panel.
See "Operator panel logo
plate" on page 4-9.
Yes
Replace the controller
board. See "Controller
board removal" on
page 4-20.
No
Replace the controller
board. See "Controller
board removal" on
page 4-20.
Replace the front cover
assembly. See "Front
cover assembly removal"
on page 4-2.
No
Replace the USB port
connector."USB port
connector removal" on
page 4-76