Lexmark C734/C736 & CS736dn Service Manual, 2009 (P/N 12G9820)

The Lexmark C734/C736 service manual (P/N 12G9820, June 8, 2009 edition) covers the C734n, C734dn, C734dnw, C736n, C736dn, and CS736dn color laser printers in the 5026 family.

Search, Bookmarks, and Page Count

Finding codes and parts: Search the PDF by error code, connector ID, or part number. Bookmarks lead to the diagnostic checks, repair procedures, connector listings, and parts catalog. Some exploded-view callouts are image labels. Zooming in makes the smallest connector labels easier to read.

The single printable PDF contains 436 pages, including the original cover, the edition page, and four pages with only running headers and footers.

Print Faults, Component Replacement, and Tray Service

These are selected service topics. The manual also covers serial-port wrap tests and disk encryption settings for printers with a hard drive.

• Fault isolation: Power-on self-test (POST), 1xx and 9xx service codes, 2xx paper jams, 3x–8x messages, and yes/no checks for power, paper-path, and networking faults.

• Print quality: Symptom tables for background, blank pages, banding, residual images, poor fusing, and missing image at the edge.

• Service menus: Tray and duplex print tests, registration and color-plane alignment, motor and sensor tests, and Mirror Motor and Servo Laser tests.

• Component repair: Step-by-step procedures for printhead removal, installation, and adjustment, plus removal and installation guidance for the fuser, Color On Demand assembly, EP drive, and transfer module.

• Paper handling: Fault checks for option-tray motors and removal procedures for high-capacity input tray (HCIT) components. The parts catalog covers the 550-sheet and Specialty Media Drawers.

• Electrical and parts references: System board connector locations, pin and signal tables, and exploded views linked to field-replaceable unit (FRU) part numbers.

Lexmark wrote the manual for printer service personnel who need to isolate faults and service replaceable assemblies.

Diagnostics and Post-Repair Checks

Service checks trace motor, sensor, cable, fuse, and board faults to likely FRUs. Static and dynamic sensor tests cover the input, exit, bubble, toner, narrow-media, bin-full, front-door, waste-toner, belt-waste, temperature, and toner-patch sensors. The networking check covers wired and wireless connections and points to the separate Network Setup Guide for further troubleshooting.

The Diagnostics and Configuration menus include panel, button, DRAM, and device tests, plus event logs, page counts, EP setup adjustments, and color-calibration resets. Quick Test pages show margin and skew during print and duplex registration. The printhead procedure covers mechanical skew and registration for black, then electrical alignment of cyan, magenta, and yellow to black.

Replacement Parts and Service Precautions

Repair instructions cover cover access, cable routing, and removal of the photoconductors, HVPS and LVPS, system board, paper-pick and multipurpose feeder/duplex mechanisms, hard drive, wireless card, and antenna. The parts catalog separates fuser part numbers by voltage and system boards by machine type. Fuser installation notes cover the counter reset and motor calibration.

The fuser autoconnect and continuity illustrations show where checks are made. The System Board Diagram and pin tables provide connector-level electrical references. Exploded views for assemblies such as Covers, Front, and Top link to FRU numbers and a separate part-number index. The screw-and-retainer table identifies fasteners by part number, location, and quantity.

For a 950.xx EPROM mismatch, replacing more than one of the system board, operator-panel card, or top-access-cover assembly at the same time can leave the printer inoperable. The manual also flags a reversed HVPS cable or an unseated camshaft follower as possible causes of a photoconductor-missing message.

Service work exposes hot fuser surfaces, hazardous voltage, and printhead laser hazards. Follow the manual's isolation, cooling, ESD, photoconductor handling, and lifting precautions.

Drawer Compatibility and Maintenance

The C734 line supports up to three input options and the C736 line up to four, with one HCIT at the bottom of the stack. Some configurations require a caster base. The C73x and X73x MFP families share media options. These distinctions help diagnose Too Many Trays Attached or Incompatible Tray messages and identify the right drawer parts.

The Error Jam Locations map links jam codes to positions in the paper path. HCIT procedures cover the controller board, elevator motor and sensor, pick rolls, photointerrupter, drawer slides, covers, and top plate.

The specifications cover installation clearances, memory and expansion, data streams, operating environment, power, acoustics, and media input and output. Preventive maintenance covers safety inspection, lubrication, exterior and printhead-lens cleaning, and moving precautions. Listed service tools include a multimeter, feeler gauges, a spring hook, parallel wrap plug P/N 1319128, Twinax/serial debug cable P/N 1381963, and coax/serial debug cable P/N 1381964.

Sample Checks for Banding and Power Faults

The horizontal-banding check uses repeating bands spaced 27 or 36 mm apart to distinguish a print-cartridge fault from a photoconductor fault.

For a printer that shows no signs of power, the service chart specifies +5 V DC between system board connector JLVPS2 pin 1 and ground as part of isolating the board, cable, and low-voltage power supply.