Apple LaserWriter

The Apple LaserWriter is Apple's first laser printer: a Canon LBP-CX engine, 300 dpi, 8 pages per minute, driven by an I/O board carrying Adobe PostScript.

Apple LaserWriter
Apple LaserWriter
Manufacturer	Apple Computer, Inc.
Type	Laser printer
Interface	AppleTalk (DB-9), RS-232 (DB-25)
Compatible	Macintosh; MS-DOS computers via RS-232
Dimensions	11.5 in. H x 18.5 in. W x 16.2 in. D (28.2 in. with trays)
Weight	77 lb
Model	M0180
Power	100-115 V AC 60 Hz (domestic); 220-240 V AC 50 Hz (international)

Before you touch one, read the Safety section. These machines contain an invisible laser, a fuser hot enough to burn, and a high-voltage supply, and Apple's own rules for working on them are specific.

Specifications

Apple's own table:

Print engine specifications

Marking engine	Canon LBP-CX laser xerographic
LaserWriter I/O board	12 MHz 68000 microprocessor; 1.5 MB RAM; 512K ROM (LaserWriter) and 1 MB ROM (LaserWriter Plus); AppleTalk and RS-232-C interfaces
Print resolution	300 dots per inch
Speed	8 pages per minute
Paper feed	Automatic from paper input cassette; manual single-sheet feed
Print materials	Best results with 16–20 lb single-sheet photocopy bond. Can use most letterhead and coloured stock from 8 to 34 lb. Can also use standard medium-weight overhead transparency material. Envelopes and labels supported via manual feed
Paper capacities	Supports Letter, Legal, A4 and B5. Input cassette holds 100 sheets; output tray holds 20 sheets
Printable surface	Letter 8.0 × 10.92 in.; Legal 6.75 × 13.0 in.; A4 7.41 × 10.86 in.; B5 7.69 × 10.16 in.
Physical dimensions	Height 11.5 in.; width 18.5 in.; depth 16.2 in. body only, 28.2 in. with trays; weight 77 lb
Operating environment	50 to 90.5 °F (10 to 34 °C); humidity 20 to 80 per cent
Power requirements	100 to 115 V AC, 60 Hz (domestic); 220 to 240 V AC, 50 Hz (international)

Two figures there are commonly overstated elsewhere. The input cassette holds 100 sheets and the output tray 20, not 250 apiece. And the depth is 16.2 in. only without trays; with them it is 28.2 in., which matters if you are measuring a shelf.

Apple's own table gives the processor as 12 MHz. The often-quoted "11.16 MHz operating speed" could not be traced to an Apple document and is not stated here, nor are wattage, current draw or BTU figures, which do not appear in this guide.

Safety

Apple's warnings, verbatim in substance:

• High voltage. The LaserWriter printers operate at high voltages. Always switch off and unplug the AC power cord before servicing. Certain parts are electrified when the printer is under power. Never work on a LaserWriter under power except when making live adjustments.
• Laser. Never disconnect the optical fibre cable or open the laser access hatch when the printer is switched on. The optical fibre carries the infrared laser beam, which you cannot see but which can permanently damage your eyes. When servicing or adjusting the optical system, do not place screwdrivers or other shiny objects in the path of the beam — the reflected beam is just as dangerous. Warning labels are attached inside the covers where there is a danger of exposure.
• Fuser. The fuser assembly rollers become very hot in operation. Switch the printer off for at least five minutes before servicing the fuser assembly to let the rollers cool.
• Do not touch, with the covers off and the printer powered: the high-voltage power supply, or the DC power supply.
• Do not be grounded when working on plugged-in equipment or performing live adjustments. Remove all jewellery before starting — removing these conductors reduces the possibility of electric shock.
• ESD. LaserWriter I/O boards contain CMOS components, among the most sensitive chips in use. CMOS chips, ROMs and SIMMs are very susceptible to electrostatic discharge and skin-acid damage. Handle them only by the edges. Do not touch anybody who is working on integrated circuits; do not wear polyester clothing or bring plastic, vinyl or polystyrene into the work area.
• Weight. LaserWriter printers weigh from 32 to 60 pounds; this one is 77 lb. Be careful lifting.
• Toner is a non-toxic substance of plastic, iron and a little pigment. Remove as much as possible from skin and clothing with a dry tissue, then wash with cold water — hot water gels it and fuses it permanently into fabric. Toner attacks vinyl, so keep it off vinyl surfaces.
• Never use an ammonia-based cleaner on a LaserWriter; it discolours the plastic.

Status Lights

There are four, not three, and one of them is not on the front panel:

LaserWriter status lights

Light	Where	Colour	Behaviour
Ready/Wait	Front display panel	Green	Flashes during warm-up; stays on continuously when ready to print
Paper-Out	Front display panel	Yellow	On and steady when out of paper or the cassette is not installed. Flashes when the printer is preparing to print a page. In manual feed mode, stays on steadily if there is no paper on the manual feed tray
Paper Jam	Front display panel	Red	Comes on when paper jams inside the printer and stays on until the jam is cleared
Test	Rear I/O connector plate	—	Comes on steady or flashing if an error condition exists with the I/O board. If the I/O board is working, the Test light flashes once and then turns off when the printer is switched on

There is no "Service" LED. The Paper-Out light is yellow, not amber, and the fourth light is on the back. The Test light's single flash at power-on is a genuine go/no-go check on the I/O board and costs nothing to observe.

Test Prints

Two different prints, testing two different halves of the machine. Knowing which is which halves the diagnostic problem immediately.

Service test print — tests the print engine

Place a jumper between pins J205-1 and J205-2 on the DC controller PCB. This confirms the operation of the print engine, and is what you use to isolate print-engine failures from I/O board failures.

User test print — tests the I/O board

Produced each time the printer is switched on, unless the protocol switch is set to "Special" or the function has been turned off with PostScript software. It confirms the I/O board works and reports:

• The revision number of the installed PostScript ROMs
• The selected operating mode — PostScript or Diablo 630 emulation
• The number of pages the I/O board has produced

So: a fault that appears on a service test print is in the engine; a fault that appears only on a user test print or when printing from the Macintosh is in the I/O board or beyond it.

Ports and Switches

The rear panel carries a 9-pin socket, a 25-pin socket and a 4-position mode switch marked AppleTalk, Special, 9600 and 1200.

AppleTalk connector — DB-9 male

Pin	Signal	Description
3	SG	Signal ground
4	TXD+	Transmit data +
5	TXD−	Transmit data −
8	RXD+	Receive data +
9	RXD−	Receive data −

The mode switch set to "AppleTalk" selects this port.

RS-232 connector — DB-25 male

Pin	Signal	Description
2	TD	Transmit data
3	RD	Receive data
4	RTS	Request to send
7	SG	Signal ground
20	DTR	Data terminal ready

The mode switch set to "1200" or "9600" selects this port. Those are the two serial rates the switch offers; a figure of 19,200 baud does not appear in Apple's own tables and is not stated here.

The AppleTalk cable is Apple's LocalTalk Connector Kit, DB-9, part number 590-0254 or 630-8272, model M2065.

Troubleshooting

Pre-power-on checklist

Apple's list of things to confirm before chasing a fault:

• Line voltage is OK — 115 V AC ±10%
• Printer is installed on a solid, level surface
• Room temperature is between 50–90 °F (10–32.5 °C) and humidity between 20% and 80%
• Printer is not in an excessively hot or humid area, near open flames, or in a dusty location
• Printer is not exposed to ammonia gas (produced by diazo copiers or cleaning solutions)
• Printer is not in direct sunlight, and is in a well-ventilated area
• Cables and connectors are OK
• Toner cartridge is installed and OK — replace if the indicator is red
• Fuser roller cleaner felt is in place and not dirty
• Print density adjustment dial is set correctly
• Protocol selector switch on the back is set to AppleTalk
• Paper cassette is properly loaded — not more than 10 mm high
• Paper is 16–21 lb standard photocopier paper
• Transfer corona wire is clean and unbroken
• Separation belt is OK — check for nicks or a broken belt

The ammonia item is not a curiosity. Diazo copiers and some cleaning products produce it, and it will degrade the machine.

The diagnostic sequence

Apple's order is fixed: pre-power-on checklist → LaserWriter Functional Check → LaserWriter Print Engine Check → the numbered troubleshooting tables. The functional check starts by switching the printer off, waiting one minute, switching it on and waiting three minutes for a user test print; if that is good, it then sends a file from a Macintosh over AppleTalk.

The tables the flowcharts hand off to include: A no power; B delivery rollers do not rotate; D heater bulb does not operate; E cannot feed paper manually; F jams detected when there are no jams; G paper jams are not detected; H Paper-Out LED lights when there is paper; J preconditioning lamps do not light; K laser/scanner malfunction; L erroneous low-toner indicator; M print quality problems; N paper transport problems.

Adjustments

Laser power adjustment

Requires a laser power checker and a digital multimeter.

1. Remove the top cover, the I/O board and the card cage.
2. With the power switched off, open the laser access hatch and insert the laser power checker with the detector facing the laser diode. Make sure it is fully inserted so that no laser light can escape from the access hatch.
3. Connect the checker's black lead to the meter's "Common" socket and the red lead to "Volts". Set the meter to volts, 200 mV range.
4. Disconnect J209 from the DC controller board and jumper J209-5 to J209-6.
5. Turn VR202 on the DC controller board fully counter-clockwise, to its lowest setting.
6. Switch on and wait until the green Ready/Wait light stops flashing.
7. Briefly jumper J209-6 to J209-7. Remove the jumper and record the reading. Repeat twice more.
8. Average the three readings and compare with the figure on the laser label — the voltage printed next to "300", ±1 millivolt.

If the output is low, remove the J209-6/J209-7 jumper, turn VR202 slightly clockwise and repeat. If high, turn it slightly counter-clockwise and repeat.

Image skew adjustment

Check first: produce a user test print and measure from the top left and right corners of the test pattern to the top edge of the paper. The difference should be no more than 1 millimetre.

To adjust:

1. Remove the top cover and the I/O board. Switch on and wait for the green Ready/Wait light to stop flashing.
2. Generate a service test print by briefly jumpering J205-1 to J205-2.
3. Loosen the four large mounting screws on the scanner unit and the two sealed screws closest to the laser unit.
4. Rotate the scanner unit around Screw A. Clockwise makes the horizontal line incline counter-clockwise; counter-clockwise makes it incline clockwise.
5. Reprint and remeasure until the difference is 1 mm or less.
6. If you run out of travel: tighten the two sealed screws nearest the laser unit, loosen the two on the other side, and rotate around Screw B instead.

Preventive Maintenance

Reading the page count

The user test print gives the number of pages printed since the installation of the I/O board — accurate only if the board has never been repaired or upgraded. If it has, Apple gives a hardware method:

1. Remove the top cover, the LaserWriter I/O board and the DC controller board.
2. Locate the preconditioning exposure assembly, just below the DC controller board.
3. The page counter is in the middle of it and looks like a small thermometer.
4. Each mark on the counter represents approximately 10,000 pages.

Apple's schedule

Preventive maintenance schedule

Number of pages	Procedure
Zero to 50,000	Standard Maintenance
50,000 to 100,000	Standard Maintenance, and replace the ozone filter
100,000 to 150,000	100,000-Page Service, and replace the separation belt

Standard Maintenance checkpoints: open and close the toner cartridge's light-blocking shutters to check they are not jammed or broken; clean the cartridge's primary corona wire with the wire brush supplied with the printer; clean the protective shield with a damp cloth; do not clean the photosensitive drum unless absolutely necessary and, if you must, use a soft cloth saturated with toner powder; replace the fuser roller cleaner felt if dirty; clean the separation claws, delivery guide, separation guide and paper guide with isopropyl alcohol; clean the transfer corona assembly and separation belt with a cotton swab; clean the feeder rollers, separation rollers, transfer guides and feeder guide with isopropyl alcohol; replace the ozone filter every 50,000 pages.

100,000-Page Service: clean the fan with a small brush; clean the registration shutter rollers with isopropyl alcohol; and replace the preconditioning exposure assembly, the grounding spring, the paper pickup rollers, the paper feed rollers and the lower paper feed guide, the fuser assembly, the ozone filter and the separation belt.

The fuser is a 100,000-page item, not a 200,000-page item, and the ozone filter is a real consumable that is frequently never changed at all.

Before starting

Power off and unplug; allow the fuser assembly rollers to cool; prepare for ESD; and spread a drop cloth to protect the floor from grease and spilled toner.

Parts

Selected entries from Apple's parts list:

Part	Number
DC Controller PCB	661-0267
DC Power Supply/Motor Drive PCB, 110 V	661-0273
DC Power Supply/Motor Drive PCB, 220 V	661-0274
High-Voltage Power Supply	661-0266
Laser Unit	661-0277
Scanner Unit, 300 DPI	661-0278
LaserWriter I/O PCB	661-0436
Fuser Assembly, 115 V	661-0450
Fuser Assembly, 220 V	699-0318
Power Interlock Assembly, 110 V	699-0324
Power Interlock Assembly, 220 V	699-0325
AC Driver PCB, 110 V	661-0268
AC Driver PCB, 220 V	661-0269
Paper Separator Belt	970-1005
Ozone Filter	970-1001
Transfer Corona Assembly	970-1021
Fan, 110 V 60 Hz	720-0502
Fan, 220 V 50 Hz	970-1074
Main Drive Motor	970-1009
Preconditioner Exposure PCB	970-1020
Registration Shutter Assembly	699-0323
Separation/Feed Roller Assembly	970-1019
Display Panel Assembly	970-1109
LaserWriter Configuration Block	750-0102

Note that the DC power supply, AC driver PCB, fuser assembly and fan are all different parts for 110 V and 220 V machines. Fitting the wrong one is a real and expensive mistake.

Other documentation on this wiki

• Envelope Feeder Service Source — Apple's service manual for the LaserWriter envelope feeder. Two incompatible feeders exist: the Pro 600/630 feeder fits only that printer, the 16/600 PS feeder fits both. The manual gives three independent ways to tell them apart (two-piece versus one-piece roller shafts, controller board RG5-0576 versus RG1-3437, serial prefix JXC versus LBK) and the 1.5 mm separation-guide gap that must be reset after a strip-down.
• Service Training Introduction To Laser Printer Service Version 1.0.1 1996 — Apple's own technician course. Teaches the diagnostic method rather than a model: establish the deviation from normal operation, act, verify. Its 1996 prerequisites are Apple's own statement of the minimum competence for this work — measure voltage and resistance with a digital multimeter, and read wiring and schematic diagrams. The 1992 edition still carries the Final Test.
• The Laser Writer Family 1992 — not an Apple document. Michael Fraase's Rapid Reference Guide to The LaserWriter Family (Business One Irwin, 1992), a user-level guide to the Personal LaserWriter LS and NT and the LaserWriter IIf and IIg, distributed "as is, without warranty". No schematic, no parts list, no FRU numbers.

See Also

• Apple LaserWriter Plus
• Apple LaserWriter II NT
• Apple LaserWriter II SC
• Apple Personal LaserWriter 300