Operator Panel Displays All Diamonds, No Beeps - Lexmark C540n Service Manual

5025-2xx, 4xx

Operator panel displays all diamonds, no beeps

Step Questions / actions
1 Turn the printer off, and remove the rear
shield. See "Top cover assembly removal"
on page 4-13.
Disconnect the cable at JOPP1 on the
controller board. Verify the following values:
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?
2-36
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
Yes
Go to step 2.
Replace the operator panel.
See "Operator panel logo
plate" on page 4-9.
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.