2004 HP Color LaserJet 2550 Series Printer Service Manual

HP's 2004 Color LaserJet 2550 Series Service Manual covers repair and maintenance for the 2550L, 2550Ln, and 2550n configurations, including differences in paper trays and network connectivity. This is Edition 1, May 2004, document reference Q3702-90923.

Supplied as one 311-page PDF in English, including the preliminary pages and covers.

• Print-engine diagnosis: Control panel light messages, event-log faults, engine tests, high-voltage connection checks, and repetitive image-defect diagnosis.

• Fuser and paper-feed repair: Fuser and fuser-motor replacement, pickup-roller and separation-pad service, paper-path checks, and fuser wrap-jam troubleshooting.

• Carousel and imaging system: Print-cartridge carousel removal, carousel-gear alignment, rotary-drive assembly replacement, and laser/scanner removal and reinstallation.

• Calibration and service functions: Printer calibration, cleaning-page procedures, cold resets, NVRAM initialization, and PJL restoration of printer data.

• Wiring and parts identification: Main wiring diagrams, connector-location drawings, printed circuit assembly diagrams, exploded assembly views, and alphabetical and numerical parts lists.

This manual is suited to trained printer service technicians familiar with ESD precautions and internal component replacement; its service-mode functions are specifically reserved for trained service personnel.

Printer Configurations and Parts Selection

The 2550Ln and 2550n have an HP Jetdirect internal print server; the 2550L accepts an optional external server. Tray 2 is standard on the 2550n and optional on the other configurations. Optional tray 3 requires tray 2.

The parts section distinguishes the 2550L formatter from the network-equipped formatter used in the Ln/n models. Physical, electrical, and environmental specification tables accompany the component data, with separate electrical specifications for 110-volt and 220-volt models and voltage-specific fuser and low-voltage PCA listings.

Print-Engine Diagnosis and Electrical References

The theory chapter maps the basic sequence of operation and image-formation stages, including laser/scanner signal paths and pickup and feed mechanics. Printed circuit assembly diagrams identify components such as the transfer-belt home-position detection PCA.

The engine test bypasses the formatter to help isolate print-engine faults, while the manual explains the formatter connection required for that test. The repetitive image-defect table links recurring mark spacing to likely drum, roller, transfer-belt, or fuser causes.

References include the Cross-section of the printer, engine control system block diagram, WAIT-period and full-color general timing charts, Dc controller connections, and the two-part Main wiring diagram. Assembly-location drawings connect the internal layout with the parts lists.

Component Replacement and Carousel Alignment

Removal and replacement coverage is limited to field-replaceable units. Beyond the imaging components, procedures cover formatter assemblies, the dc controller, ECU pan, high-voltage transformer PCA, transfer roller, and registration-roller assembly.

Reinstallation notes address carousel-gear alignment, pressure-shaft-holder positioning, ECU grounding springs, and cable routing. The rotary-drive section covers the developer motor, brake solenoid, and encoder motor as an assembly.

The manual warns that rotating the carousel manually while power is connected can damage the printer. It also identifies a cable-damage risk from attempting to disconnect the paper-top sensor cable at the sensor itself.

Internal repair requires electrical isolation and attention to high-voltage circuits, hot fuser surfaces, and ESD-sensitive assemblies.

Calibration, Resets, and Imaging-Drum Life

Calibration procedures cover the printer control panel and HP LaserJet Toolbox. Supplies-life information distinguishes black-only, color, and mixed printing and explains how calibration cycles and short print jobs affect imaging-drum life.

Service-mode coverage distinguishes cold resets, NVRAM initialization, super NVRAM initialization, and network-card resets. The NVRAM section identifies the settings and counters affected by initialization.

PJL data-restoration procedures address printer identity and page counts after formatter replacement or initialization. The documented PJL method requires a direct parallel connection; USB and network connections are not supported for this procedure.

PDF Navigation and Diagram Readability

The total includes 294 numbered manual pages, 12 preliminary pages, and five unnumbered cover, title, and blank pages. Embedded bookmarks cover all seven chapters and the index; body text and parts lists are searchable, but image-based diagram labels are not. Small labels in the main wiring diagrams and DC controller view require zooming.