Lexmark C930, C935 Color Laser Printer 2007 Service Manual (P/N 12G9765)

• Original Lexmark 568-page PDF, edition May 23, 2007, P/N 12G9765, for C930 (5057-030) and C935 (5057-230) network models.
• Distinguishes the base and configured machines, with dedicated theory, diagnostics, repair procedures, connector views, wiring, and parts coverage for the 1TM, 3TM, and 2000-sheet tandem tray module (TTM).
• Traces media through the MPF, trays, registration, second transfer, fuser, duplex, bridge, and output paths, then explains printhead scanning and the complete xerographic cycle.
• Covers 200-series jams; controller, drive, printhead, transfer-belt, fuser, fan, RFID, ATC, tray-sensing, and communications faults; consumable/interlock messages; and image-quality troubleshooting.
• Provides service-menu access, individual motor and sensor tests, feed and print tests, event-log functions, failure clears, developer-unit reset, ATC sensor setup, and RegCon color-registration routines.
• Details removal and replacement of major mechanical, xerographic, drive, electrical, duplex, controller, and modular-tray FRUs.
• Includes finisher interface diagnostics and adjustments, connector-location views, two full wiring diagrams, and a 53-assembly illustrated FRU parts catalog. Internal finisher teardown and repair require the separate Finisher Service Manual.

Platform Theory & Configuration Coverage

All service information applies to both C930 and C935 models unless the manual states otherwise. Basic and fully configured machine drawings identify the integrated trays, MPF, duplex, bridge unit, and optional finisher. The engine theory then breaks out media feed, registration, transfer, printhead, fuser, exit, drive, and controller functions instead of treating the printer as a single block.

Separate TTM, 3TM, and 1TM chapters map their transport paths and identify the feed/lift motors, TTM tray-4 transport drive, size switches, media-level and media-out sensors, feed-out sensors, interlocks, and controller cards. This configuration split is important when a tray-specific feed, sensing, or 980-series communications fault must be matched to the correct module before repair parts are selected.

The xerographic section follows the image through charge-roll HVPS operation, laser exposure, development, transfer to the belt, second transfer to the sheet, drum cleaning, discharge, and fusing. Printhead coverage explains the polygon-mirror drive, start-of-scan signals, four-color laser paths, and shutter system. Fuser theory ties the main and sub heater lamps to the thermostat, front and rear thermistors, warm-up control, and fuser-exit sensing.

Diagnostics, Repair Procedures & Adjustments

The error-code table routes core printer and tray-module faults into service checks for named sensors, motors, clutches, controller cards, power supplies, connectors, and harnesses. Image-quality paths cover faint or blank output, solid black, white lines and stripes, spots, afterimage, background fog, skew, media damage, unfused toner, color misregistration, deletions, and banding. Finisher jam and service codes are decoded, but internal finisher repair is deliberately referred to its own publication.

The Diagnostics Menu can exercise the printhead polygon motor, PC and developer drives, transfer-belt steering and drive, registration clutch, second-transfer retract mechanism, fuser fan, toner-add motors, duplex drive, tray feed/lift motors, tray-module drives, and finisher mechanisms. It also supports source-specific print tests, hardware checks, duplex and tray feed tests, base-sensor status, staple and hole-punch tests, and event-log display, print, and clear functions.

Engine adjustments include ATC value entry and setup cycles after developer-unit replacement, plus RegCon measurement, control-sensor, belt-edge learn, fine/rough skew, in/out, and center setup. Related factory repair coverage reaches the image-density sensor, transfer belt and cleaner, second-transfer and registration mechanisms, printhead and shutter drive, developer units and carriers, toner-add and waste-toner systems, fuser, duplex inverter/controller, RIP card and hard drive, engine cards, HVPS/LVPS cards, fans, motors, sensors, switches, and all three tray modules. The service-tool list calls out the parallel wrap plug P/N 1319128 and twinax/coax serial debug cables P/N 1381963/1381964, along with a multimeter, spring hook, and approved toner vacuum.

The manual also flags several repair traps. Touching the transfer-belt surface during removal can damage it. Cable ties removed for access must be restored so harnesses cannot be pinched, obstruct the media path, or restrict movement. New developer units require their ATC data to be entered, and the image-density sensor must be correctly positioned for RegCon or print-quality and calibration problems can follow.

Maintenance, Schematics & Parts Identification

Preventive maintenance is organized by every service call and the 100K and 600K intervals. The schedules cover feed, pick, and separation rolls; registration and tray sensors; printhead slit glass; developer components; second-transfer roll; transfer belt and cleaner; fuser; duplex rolls; bridge-unit rolls; and finisher checkpoints. Maintenance-kit identification, approved lubricant specifications, cleaning areas, and the factory maintenance-counter reset procedure are included.

Key graphics include SFP media-path roll and sensor maps, four-color printhead laser-path views, the xerographic-process diagram, controller/HVPS connector locations, the full 5057 printer wiring diagram, and the 5057/7510 tray-module wiring diagram. The parts catalog supplies 53 exploded assembly illustrations with FRU tables for the base engine and 1TM/3TM/TTM hardware, followed by a part-number index.

Service work requires power isolation before disconnecting boards or cables, ESD control for electronic FRUs, adequate fuser cool-down, and suitable lifting support for the 383-lb printer and optional finisher assemblies.