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Apple Personal LaserWriter 320 General Maintenance

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Personal LaserWriter 320 (All About Apple museum, CC BY-SA 3.0)

Care, handling and adjustment procedures for the Apple Personal LaserWriter 320, from chapter 4 of Apple's July 1995 Service Guide: LaserWriter Printers, Volume III. That chapter covers the 320 and the LaserWriter 4/600 PS together; both use the Canon P90 engine.[1] Much of the engine is the same as the Apple Personal LaserWriter 300's: the controller assembly, laser/scanner assembly and fuser assemblies carry the same Apple part numbers in both printers' parts lists.[2] Fault-finding is on Apple Personal LaserWriter 320 Troubleshooting Guide.

Safety

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Warning: the printer has mains wiring, a fuser that becomes very hot, a high-voltage supply and an invisible laser.

Apple's rules:[1]

  • Switch off and unplug the printer before servicing it. Remove rings and watches.
  • With the cover off and power on, do not touch the high-voltage contact assembly or the power supply.
  • Never remove the cover of the laser/scanner assembly, whether the printer is on or not, and keep screwdrivers and other shiny objects out of the beam path. The reflected beam is invisible and can permanently damage your eyes.
  • Switch off for at least five minutes before working on the fuser.
  • Do not wear an earthing strap while working on plugged-in equipment or making live adjustments.

If the fan will not start, Apple's first step is to unplug the printer and wait 4 minutes before plugging it in again, "because of the possibility of a capacitor error".[3]

Toner is non-toxic. Remove it from skin and clothing with a dry tissue, then cold water; hot water makes it set into fabric. It attacks vinyl.[1]

Toner cartridge and light

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The drum inside the toner cartridge is exposed whenever the printer cover is off. Room light for more than five minutes can damage it and cause blank spots or black stripes on the page. Apple's rules:[1]

  • Do not leave the rear access door open with a cartridge fitted.
  • Cover the cartridge whenever it is out of the printer, and keep opened cartridge packs out of direct sunlight.
  • Lay a sheet of paper over the cartridge when printing with the cover off.
  • When printing with the cover off, press down on the cartridge so that it touches the HVT connector assembly; without that pressure the pages come out blank.

A cartridge that has been exposed to ordinary room light may recover if it is left somewhere dark, such as a drawer, for several hours. Do not put it in direct sunlight.[1]

Paper

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The universal cassette takes 100 sheets of 17-20 lb single-sheet photocopy bond. Feed letterhead, coloured stock, transparencies, envelopes, labels and paper up to 28 lb one sheet at a time through the manual slot. The face-down tray holds 25 sheets; transparencies, labels and postcard stock leave through the face-up slot only and must be taken out by hand.[1] The paper delivery selector chooses the output: down for face-up, up for face-down, which is the default.[1]

Apple's rules for avoiding jams: do not reload printed pages into the cassette (use manual feed for the second side), wait for the on-screen prompt before inserting each manually fed sheet, and keep the cassette loaded with recommended paper.[1]

Memory

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The 320 has 2 MB and one slot for a RAM expansion card. A 2 MB card (661-0688) brings it to the 4 MB it needs to print edge to edge on legal paper; a 6 MB card (661-0689) brings it to the 8 MB it needs for PhotoGrade.[1][2]

Mirror adjustment

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The reflecting mirror is set at the factory. Readjust it after replacing the mirror or the laser/scanner assembly:[1]

  1. Line up the adjustment scale on the mirror assembly with the mark on the printer chassis.
  2. Load letter paper and print a service test page (see Apple Personal LaserWriter 320 Troubleshooting Guide#Service test page).
  3. With a straight edge, draw a line across the tops of the vertical lines on the test page. Set a triangle against the first vertical line and trace its top edge.
  4. Measure the error between the two lines.
  5. If the error is more than 1.5 mm, move the scale in 1 mm steps. Moving the mirror towards the laser/scanner raises the left side of the image; moving it away raises the right side.
  6. Print another test page and repeat until the error is 1.5 mm or less.

Registration adjustment

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Adjust registration whenever the controller assembly is replaced. The target is 2 mm from the leading edge of the paper to the printed pattern, set with VR301 on the controller assembly.[1]

  1. Turn VR301 to "0" with a jeweller's screwdriver.
  2. Switch on and let the printer warm up.
  3. Print three service test pages.
  4. Measure the distance from the top of each page to the edge of the test pattern and average the three.
  5. Set VR301 from the table below. When the average is over 2.0 mm the setting is negative (anticlockwise); under 2.0 mm it is positive (clockwise).
  6. Print three more pages and repeat if the average is not 2.0 mm.
VR301 settings, Personal LaserWriter 320 (Apple's Figure 57)[1]
Average over 2.0 mm by (mm) VR301 Average under 2.0 mm by (mm) VR301
0.30 −1 0.30 +1
0.61 −2 0.61 +2
0.90 −3 0.90 +3
1.22 −4 1.22 +4
1.50 −5 1.50 +5
1.83 −6 1.83 +6
2.10 −7 2.10 +7
2.44 −8 2.44 +8
2.74 −9 2.74 +9
3.04 −10 3.04 +10

Apple's worked example in the 1995 service guide is an average of 2.6 mm: 0.6 mm too long, so VR301 goes to −2. The table agrees with it.[1]

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References

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  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 Apple Computer, Inc., Apple Service Guide: LaserWriter Printers, Volume III (072-0142, July 1995), hosted as File:Apple Service Guide LaserWriter Printers Volume III July 1995.pdf; described at Apple Service Guide Laserwriter Printers Volume Iii July 1995. Safety, pp. 2-6 (PDF pp. 12-16): high voltages and unplugging, the safety rules, toner, laser and fuser safety, ESD rules and not being grounded while working live. Chapter 4 (PDF page = printed page + 7): Canon P90 engine and specifications, Table 79 (p. 169); paper paths and the paper delivery selector (p. 171); RAM cards in the parts list (p. 166); mirror adjustment (pp. 178-179); registration adjustment and Figure 57 (p. 180); troubleshooting tips on drum exposure, avoiding paper jams and printing with the cover removed (p. 182); Tables 102 and 103 (p. 200).
  2. ↑ 2.0 2.1 Apple Service Guide: LaserWriter Printers, Volume III, Parts List, pp. 165-166 (PDF pp. 172-173), and Apple Service Guide: LaserWriter Printers, Volume 2 (072-0632, September 1993), Personal LaserWriter 300 Parts List, pp. 141-142 (PDF pp. 146-147), hosted as File:Apple Service Guide LaserWriter Printers Volume II Sept 1993.pdf. Source for: controller assemblies 661-0029 (120 V) and 661-0028 (240 V), laser/scanner assembly 661-0027, fuser assemblies 661-0025 (110 V) and 661-0026 (220 V), fixing film assemblies 922-0450 (110 V) and 922-0451 (220 V), paper pickup roller, arm registration assembly 922-0470, mirror assembly 922-0468, and the 320's RAM cards 661-0688 (2 MB) and 661-0689 (6 MB).
  3. ↑ Apple Service Guide: LaserWriter Printers, Volume III, Table 81, No Power to Fan, p. 185 (PDF p. 192).


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