Lexmark C540 Service Manual - Page 73

5025-2xx, 4xx Operator panel displays all diamonds, no beeps Step Questions / actions Yes No 1 Turn the printer off, and remove the rear shield. See "Rear shield removal" on page 4-11. Disconnect the cable at JOPP1 on the controller board. Verify the following values: JOPP1 Pin 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 Are all these values approximately correct? 2 Check for continuity in the operator panel 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? Go to step 2. Replace the operator panel. See "Operator panel removal" on page 4-9. Replace the controller board. See "Controller board removal" on page 4-19. Replace the front cover assembly. See "Front cover assembly removal" on page 4-2. Diagnostic information 2-39