Apple LaserWriter 12/640 PS General Maintenance

A LaserWriter 12/640 PS (Mikerajchel, Wikimedia Commons, public domain)

Routine care for the Apple LaserWriter 12/640 PS, from Apple's user's manual and Service Source. Apple describes the printer as needing little more than a new toner cartridge every 6,000 pages or so and a few cleaning tasks, with a recommended service interval of 120,000 pages to check and service wear on the rollers and fuser. Fault-finding, including Apple's REA repairs, is on Apple LaserWriter 12/640 PS Troubleshooting Guide.

Safety

• The fixing rollers run at about 400 °F (204 °C). Let them cool before maintenance or troubleshooting.
• The printer has a three-pin earthed plug; do not defeat the earth. Unplug it before cleaning, and pull the plug, not the cord.
• The laser shutters, one in the laser/scanner and one over the mirror assembly, are opened by closing the top cover.
• Never use ammonia-based cleaners on or near the printer. Apple says they react with the toner and with the plastic case.
• Apple's user's manual says not to lubricate the printer, not to take it apart and not to put anything on top of it.

Toner cartridge change

Apple's toner cartridge for this printer is M4683G/A, rated at about 6,000 pages at 5% coverage. Apple warns that other cartridges may not fit and may damage the printer.

1. Lift the latch and open the top cover.
2. Pull the old cartridge up and out.
3. Slide the cleaner square in the printer back and forth to remove toner residue. The user's manual calls it the yellow plastic square; the Service Source describes it as a peach-coloured slider built into the mirror assembly that cleans the mirror.
4. Take the new cartridge out of its packaging and rock it gently to spread the toner.
5. Pull the sealing tape tab straight out, firmly but not too fast and not at an angle, or the toner seals inside can be damaged.
6. Line up the arrow on the left of the cartridge with the arrow on the left of the printer and slide the cartridge down until it is fully seated. Close the cover.

Apple's print-quality tables use the same mirror cleaner as the first step for light prints and vertical white bands.

Clean the outside with a soft damp cloth, with mild soap if needed, and keep liquid out of the power inlet.

Paper

Use 16-28 lb (60-90 g/m²) laser bond in the cassette. Stock up to 50 lb (190 g/m²) has to be fed through the multipurpose tray and delivered to the face-up tray, for one-sided printing only. Paper must survive 200 °C for 0.1 seconds without scorching, melting or giving off fumes. Fan the stack before loading, do not overfill the cassette, and print stiff stock from the multipurpose tray, which has a straighter path. Keep the paper under the bracket at the front of the cassette: paper riding over it is reported as a jam.

If letter paper is used in the cassette, set the cassette's paper-length guide to the letter position; as shipped it is set for A4, and PostScript's AutoSelect then looks in the multipurpose tray instead.

Where to put it

A flat, stable, ventilated place out of direct sunlight and away from heat, cold and humidity, with the vents clear and room to open the top cover and the cassette. Apple's operating range is 10-32 °C and 15-80% relative humidity. Store toner cartridges at 0-35 °C and 15-85% RH, and the printer at 0-40 °C and 35-85% RH, all non-condensing.

Preventive repairs under Apple's REA programme

Apple's Repair Extension Authorization programme for the 12/640 PS combined four preventive jobs: removing capacitor C102 from the DC controller board, burnishing the lower exit actuator, checking the cassette pinch roller clearance (about 1 mm, tested with a business card) and resetting the multipurpose tray pressure plate. Printers that have had the work carry a white dot on the chassis left of the cassette opening. The procedures are on the troubleshooting page.

Memory

RAM is added in 72-pin SIMMs of 70 ns or faster in two slots, C/D on the left and A/B on the right; the printer ships with 4 MB in A/B. Duplex printing and PhotoGrade each need at least 12 MB, and both together 20 MB (24 MB on legal paper). If the printer reports a service error after a memory upgrade, check that the SIMMs are fully seated in a supported layout.

Capacitors

Apple's documents give no component-level parts list or capacitor values for this printer, so there is no recapping guide. The one capacitor Apple's documents single out is C102 on the DC controller, which the REA programme removes without a replacement.

Related pages

• Apple LaserWriter 12/640 PS Troubleshooting Guide
• Apple LaserWriter 12/640 PS
• Apple LaserWriter 12/640 PS Documentation