1998–2001 HP DesignJet 1050C / 1055CM Printer Factory Service Manual (P/N C6071-90000)

HP's first-edition service manual covers testing, calibration and repair of the original HP DesignJet 1050C (C6074A) and HP DesignJet 1055CM (C6075A) large-format printers. Routine printer operation is covered in the separate User and Quick Reference Guides.

• Electronic diagnostics: Electronics Module, DRAM, Trailing Cable, Carriage Assembly, EIO card and hard-disk tests, with continuable, non-continuable and initialization error-code troubleshooting.

• Ink delivery and supplies: HP No. 80 supplies, Ink Supply Station (ISS), Tubes System and Air Pressurization System (APS), including priming, Tubes Purge and leak isolation.

• Service calibrations: Media-advance accuracy, Line Sensor, Service Station, Roller Mark Position, Color-to-Color, Pen Alignment, Carriage Height and EEROM calibration backup.

• Removal and installation: Electronics Module, carriage and belt, encoder strip, trailing cable, cutter, platen, drive roller and paper-entry components.

• Print-quality troubleshooting: Nozzle Print Test, Color Alignment Print Test and Overall Print Quality Test in BEST mode, with diagnosis of banding and line defects.

• Parts and maintenance: HP parts tables, exploded assembly views, Carriage Height Tool identification, Carriage Interconnect Wiper guidance and preventive maintenance.

The procedures in this manual are intended for HP-certified service personnel.

Electronic Diagnostics and Printer Configuration

The Electronic Systems test groups board, memory, cable and carriage checks, with failure displays and component-isolation guidance. This helps narrow a fault to the affected assembly before replacement. Separate tests address the Ink Pressure System, Scan Axis, Paper Axis and Drop Detector.

The Service Configuration Print records firmware, installed configuration, printhead and cartridge data, operating temperature and humidity, and completed calibrations. Its maintenance information includes power-on and carriage-cycle counts and the last system error; the JetDirect section records network configuration. These records help distinguish hardware faults from consumable, environmental or configuration problems.

Model configurations: The Functional Overview lists the 1050C with a network interface, 16 MB of memory and no hard disk. The 1055CM has a network interface, 32 MB, a 2.1 GB hard disk and a PostScript-ready configuration.

The Printer Model Type utility addresses model identification when the Tubes System and Electronics Module have both been replaced at the same time. Service-test instructions also explain the power cycle required before returning to normal printing.

Ink Delivery and Print-Quality Diagnosis

The functional overview explains how Ink Level Sensing (ILS) monitors cartridge contents and how the Leak Detect System (LDS) monitors the tube-leak collector. Printhead Cleaner descriptions cover the cap, wiper, spittoon and snout wiper.

Test-pattern interpretation: Nozzle patterns distinguish missing, partially firing and misdirected nozzles. Twelve color-alignment patterns show registration errors, while a seven-color BEST-mode pattern addresses banding in dense fills.

Further troubleshooting covers media-advance banding, stepped or missing lines, smearing, scratching, cockling and printhead crashes. Color inconsistency and glossy-media bleed are addressed alongside the relevant media and configuration conditions. Front-panel recovery, alignment and calibration functions are linked to the defects they address.

Assembly Repair, Calibration and Parts Reference

Illustrated removal and installation procedures also cover the Service Station, Drop Detector, vacuum fan, paper- and scan-axis motors, ISS/APS, Tubes System, ink leak detector and pinch-wheel assembly. The chapter follows disassembly order, supporting individual assembly replacement through a full mechanical strip-down.

Post-repair calibration: A matrix maps work on the carriage, Electronics Module, paper axis, platen, Service Station, drive roller and Tubes System to the calibrations that follow. It includes calibrations required after disassembly for access, helping technicians account for work beyond the assembly being replaced.

Calibrations Backup covers EEROM data after Electronics Module or Tubes System replacement. The obsolete Pen-to-Paper Spacing entry is explicitly marked as a calibration that must not be performed.

Carriage Height adjustment uses the Carriage Height Tool (P/N C6071-60166) and includes precautions for moving the carriage by its belt. The Carriage Interconnect Wiper is covered for printhead and carriage electrical-contact cleaning.

Installation cautions: Incorrect Trailing Cable installation can burn the Electronics Module's internal fuse; the manual illustrates seating position and a continuity check. Interrupting an EEROM test or clear operation can also damage the Electronics Module, and the recovery information addresses calibration backup and stored settings.

Parts tables and exploded views cover the Electronics Module, ISS and APS Assembly, and Carriage Assembly. Scan-Axis Assemblies, Paper Path Assemblies and Tubes Guide Assemblies provide further references for identifying components. Preventive maintenance addresses overdrive cleaning, slider-rod lubrication, carriage-bushing noise, belt storage and usage-based maintenance.

Electrical Coverage and Service Precautions

Electrical coverage centers on functional PSU/PCA descriptions, cable connections, assembly diagnostics and test data. This is an assembly-service reference rather than a complete point-to-point wiring-schematic manual.

Disconnect the printer from AC power before opening it and follow the manual's grounding and ESD precautions. Service-test mode bypasses normal initialization and disables cover-sensor protection, requiring particular care around moving assemblies.

A Preview of Internal PSU Output Ratings

These examples are a small selection from the manual's electrical specifications.

For the microprocessor, memory and digital logic, the PSU table lists a +3.3 V output with a maximum output current of 12.0 A. The +24 V output for analog power systems and the carriage supply is listed at 13.5 A maximum.

These are individual internal PSU output ratings, presented alongside functional descriptions and connector information.

PDF Text Search and Reproduced Report Detail

Search and report readability: Regular manual text is searchable, while text inside reproduced configuration-print images is not. There are no embedded PDF bookmarks. Some small labels in the sample Service Configuration Print remain blurred when enlarged.

One printable 320-page PDF in English. The total already includes two covers, six nearly blank section pages, one page of edition information and one supplementary information page.