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{{Infobox computer peripheral
{{Infobox computer peripheral
| name        = Apple LaserWriter II NT
| name        = Apple LaserWriter II NT
| image        = [[File:Apple_LaserWriter_II.jpg|250px]]
| image        = [[File:Apple LaserWriter II (All About Apple museum).jpg|260px|frameless]]
| caption      = Apple LaserWriter II
| caption      = Apple LaserWriter II (the NT, SC and NTX share this case)
| manufacturer = Apple Computer, Inc.
| manufacturer = Apple Computer, Inc.
| type        = Laser printer
| type        = Laser printer
| interface    = LocalTalk / RS-422 (mini DIN-8); RS-232 (DB-25); Apple Desktop Bus connector present
| interface    = LocalTalk / RS-422 (mini DIN-8); RS-232 (DB-25); Apple Desktop Bus connector present
| compatible  = Macintosh; other computers via RS-232
| compatible  = Macintosh; other computers over RS-232
| dimensions  = 8.6 in. H x 20 in. W x 18.5 in. D
| dimensions  = 8.6 in high × 20 in wide × 18.5 in deep
| weight      = 45 lb (20.25 kg)
| weight      = 45 lb (20.25 kg)
| power        = 90-126 V AC, 50-60 Hz
| power        = 90-126 V AC, 50-60 Hz
| part_number  = 661-0438 (NT controller-I/O board)
}}
}}
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<templatestyles src="Template:StyledTable/styles.css" />
The '''Apple LaserWriter II NT''' is the PostScript member of the LaserWriter II range. It shares the '''Canon LBP-SX''' engine, the case, the power supply and the entire mechanical parts list with the [[Apple LaserWriter II SC|II SC]] and the NTX; what makes it an NT is its controller-I/O board — a '''68000 at 11.16 MHz''' with '''1.0 MB of ROM''' and '''2.0 MB of RAM''', speaking '''PostScript''' and '''Diablo 630''' over LocalTalk, RS-232 and RS-422.<ref name="asg">''Apple Service Guide for LaserWriter Printers, Volume I'', Apple Computer, Inc., January 1992 (072-0631-B) — hosted on this wiki as [[Apple LaserWriter Printers Volume I]] ([[:File:Apple LaserWriter Printers Volume I.pdf|PDF]]). Covers the LaserWriter, LaserWriter Plus, LaserWriter II SC/NT/NTX/IIf/IIg and Personal LaserWriter SC/NT/LS. Introductory safety section: the high-voltage, optical-fibre, fuser-cooling, ESD, not-being-grounded and lifting warnings; the LaserWriter Safety Rules; the toner-safety paragraph; the laser-safety paragraph and the three laser warning labels. Tab 3, LaserWriter II: parts list including the NT controller-I/O board and its ROM set (pages 4–5); controller-I/O board specifications (page 10); print engine specifications (page 11); status LEDs (page 12); test pages (page 13); the pre-power-on checklist, the troubleshooting flowcharts and tables including the NT low-toner note (pages 14–54); the laser power output check (page 55); and preventive maintenance including the page count, the parts replacement schedule and the user and standard maintenance tables (pages 59–60). Tab 6, Ports and Cables: the peripheral cable table, external connector diagrams, the RS-422 and RS-232 pin-outs and the LaserWriter II NT switch configuration table.</ref>
The '''Apple LaserWriter II NT''' is the PostScript member of the LaserWriter II range. It shares the Canon LBP-SX engine, the case, the power supply and the mechanical parts with the [[Apple LaserWriter II SC|II SC]] and the NTX. Its controller-I/O board has a 68000 at 11.16 MHz, 1.0 MB of ROM and 2.0 MB of RAM, and runs PostScript and Diablo 630 emulation over LocalTalk, RS-232 and RS-422.<ref name="asg">''Apple Service Guide for LaserWriter Printers, Volume I'', Apple Computer, Inc., January 1992 (072-0631-B), hosted on this wiki as [[Apple LaserWriter Printers Volume I]] ([[:File:Apple LaserWriter Printers Volume I.pdf|PDF]]). Covers the LaserWriter, LaserWriter Plus, LaserWriter II SC/NT/NTX/IIf/IIg and Personal LaserWriter SC/NT/LS. Introductory safety section: the high-voltage, optical-fibre, fuser-cooling, ESD, not-being-grounded and lifting warnings; the LaserWriter Safety Rules; the toner-safety paragraph; the laser-safety paragraph and the three laser warning labels. Tab 3, LaserWriter II: parts list including the NT controller-I/O board and its ROM set (pages 4-5); controller-I/O board specifications (page 10); print engine specifications (page 11); status LEDs (page 12); test pages (page 13); the pre-power-on checklist, the troubleshooting flowcharts and tables including the NT low-toner note (pages 14-54); the laser power output check (page 55); and preventive maintenance including the page count, the parts replacement schedule and the user and standard maintenance tables (pages 59-60). Tab 6, Ports and Cables: the peripheral cable table, external connector diagrams, the RS-422 and RS-232 pin-outs and the LaserWriter II NT switch configuration table.</ref> Read the [[#Safety|Safety]] section before taking the covers off: the printer contains an invisible laser, a fuser that needs five minutes to cool, and a high-voltage supply for the coronas.
 
'''Before you take the covers off, read the [[#Safety|Safety]] section.''' There is an '''invisible''' laser inside, a fuser that needs five minutes to cool, and a high-voltage supply for the coronas.
 
== Controller-I/O Board ==
 
Apple's table for the whole range, which is the clearest single comparison available:<ref name="asg" />


== Controller-I/O board ==
{| class="wikitable styled-table" style="width:95%;"
{| class="wikitable styled-table" style="width:95%;"
|+'''Controller-I/O board specifications'''<ref name="asg" />
|+'''Controller-I/O board specifications, LaserWriter II range'''
! !! SC !! '''NT''' !! NTX !! IIf !! IIg
! !! SC !! NT !! NTX !! IIf !! IIg
|-
|-
| '''CPU''' || 68000 (7.45 MHz) || '''68000 (11.16 MHz)''' || 68020 (16.67 MHz) || 68030 '''(20.0 MHz)''' || 68030 (25.0 MHz)
| CPU || 68000 (7.45 MHz) || 68000 (11.16 MHz) || 68020 (16.67 MHz) || 68030 (20.0 MHz) || 68030 (25.0 MHz)
|-
|-
| '''ROM''' || 16 KB || '''1.0 MB''' || 1.0 MB || 2.0 MB || 2.0 MB
| ROM || 16 KB || 1.0 MB || 1.0 MB || 2.0 MB || 2.0 MB
|-
|-
| '''RAM''' || 1.0 MB || '''2.0 MB''' || 2.0 MB, expandable to 12 MB || 2.0 MB, expandable to 32 MB || 5.0 MB, expandable to 32 MB
| RAM || 1.0 MB || 2.0 MB || 2.0 MB, expandable to 12 MB || 2.0 MB, expandable to 32 MB || 5.0 MB, expandable to 32 MB
|-
|-
| '''I/O''' || SCSI || '''LocalTalk, RS-232, RS-422''' || LocalTalk, RS-232, RS-422, SCSI || LocalTalk, RS-232, RS-422, SCSI || LocalTalk, RS-232, RS-422, SCSI, Ethernet
| I/O || SCSI || LocalTalk, RS-232, RS-422 || LocalTalk, RS-232, RS-422, SCSI || LocalTalk, RS-232, RS-422, SCSI || LocalTalk, RS-232, RS-422, SCSI, Ethernet
|-
|-
| '''Imaging languages''' || QuickDraw || '''PostScript, Diablo 630''' || PostScript, Diablo 630, HP LaserJet || PostScript Level 1 & 2, HP LaserJet IIP || PostScript Level 1 & 2, HP LaserJet IIP
| Imaging languages || QuickDraw || PostScript, Diablo 630 || PostScript, Diablo 630, HP LaserJet || PostScript Level 1 and 2, HP LaserJet IIP || PostScript Level 1 and 2, HP LaserJet IIP
|-
|-
| '''Built-in fonts''' || Times, Helvetica, Courier, Symbol || '''Times, Courier, Symbol, Palatino, Helvetica, Helvetica Narrow, ITC Bookman, ITC Avant Garde, ITC Zapf Chancery, New Century Schoolbook, ITC Zapf Dingbats''' || as NT || as NT || as NT
| Built-in fonts || Times, Helvetica, Courier, Symbol || Times, Courier, Symbol, Palatino, Helvetica, Helvetica Narrow, ITC Bookman, ITC Avant Garde, ITC Zapf Chancery, New Century Schoolbook, ITC Zapf Dingbats || As NT || As NT || As NT
|}
|}
<ref name="asg" />


Three things in that table are commonly misreported. '''The NT runs at 11.16 MHz''', not 11.5. '''The IIf runs at 20.0 MHz''', not 25.0 — the IIg is the 25 MHz machine. And Apple's guide '''gives eleven font families, not a font count'''; the familiar "35 fonts" figure is a count of individual styles that Apple's service documentation does not state, so it is not given here.
Apple's guide gives memory upgrade procedures for the NTX and the IIf/IIg, and none for the NT, whose 2.0 MB is fixed.<ref name="asg" />
 
'''The NT's 2.0 MB is not expandable.''' Apple documents memory upgrades for the NTX and for the IIf/IIg only; there is no NT memory upgrade in the guide.<ref name="asg" />


=== Board layout ===
=== Board layout ===
 
Apple's service course diagram of the NT controller-I/O board shows an MC68000, a 6532, an 8530 SCC, 1 MB of ROM, 2 MB of RAM and SRAMs, with the Apple Desktop Bus connector, a two-position switch, the RS-232 port and the LocalTalk/RS-422 port along the back panel. The board connects to the print engine through a 32-pin right-angle connector that engages as the board slides into its guide rails.<ref name="train">''Apple Service Training: LaserWriter II Service Course, Participant Manual, Version 1.1'', Apple Computer, Inc., October 1992, hosted on this wiki as [[Apple Laserwriter Ii Service Training Participant Manual Version 1.1 Oct 1992|LaserWriter II Service Course: Participant Manual]] ([[:File:Apple LaserWriter II Service Training Participant Manual Version 1.1 Oct 1992.pdf|PDF]]). Module 1, "LaserWriter II Parts and Functions": the SC, NT and NTX I/O board block diagrams and back panels (figures 1-3 to 1-5) and the 32-pin right-angle engine connector; the four-subsystem breakdown (power distribution, control, image formation, pickup/feed); the power distribution diagram (figure 1-7); the DC controller PCB's role; the interlock switch at the top of the DC power supply; the status panel description; the distribution PCA (figure 1-12) with drum-sensitivity switches SW301 and SW302, pickup solenoid SL301, registration clutch solenoid SL302, paper-out sensor PS301 and manual feed sensor PS302; and paper delivery sensor PS331 on the fuser PCA.</ref>
Apple's service course diagram of the NT controller-I/O board shows an '''MC68000''', a '''6532 VIA''', an '''8530 SCC''', '''1 MB of ROM''', '''2 MB of RAM''' and a bank of SRAMs, with the Apple Desktop Bus connector, a '''two-position switch''', the RS-232 port and the LocalTalk/RS-422 port along the back panel. The board mates with the print engine through a '''32-pin right-angle connector''' that engages as the board slides into the guide rails in the base of the engine.<ref name="train">''Apple Service Training: LaserWriter II Service Course, Participant Manual, Version 1.1'', Apple Computer, Inc., October 1992 — hosted on this wiki as [[Apple Laserwriter Ii Service Training Participant Manual Version 1.1 Oct 1992|LaserWriter II Service Course: Participant Manual]] ([[:File:Apple LaserWriter II Service Training Participant Manual Version 1.1 Oct 1992.pdf|PDF]]). Module 1, "LaserWriter II Parts and Functions": the SC, NT and NTX I/O board block diagrams and back panels (figures 1-3 to 1-5) and the 32-pin right-angle engine connector; the four-subsystem breakdown (power distribution, control, image formation, pickup/feed); the power distribution diagram (figure 1-7); the DC controller PCB's role; the interlock switch at the top of the DC power supply; the status panel description; the distribution PCA (figure 1-12) with drum-sensitivity switches SW301 and SW302, pickup solenoid SL301, registration clutch solenoid SL302, paper-out sensor PS301 and manual feed sensor PS302; and paper delivery sensor PS331 on the fuser PCA.</ref>


=== Board and ROM part numbers ===
=== Board and ROM part numbers ===
{| class="wikitable styled-table" style="width:70%;"
{| class="wikitable styled-table" style="width:70%;"
|+'''NT controller-I/O board'''<ref name="asg" />
|+'''NT controller-I/O board'''
! Part !! Number
! Part !! Number
|-
|-
| Controller-I/O Board, LW II NT || '''661-0438'''
| Controller-I/O board, LW II NT || 661-0438
|-
|-
| IC, ROM, L0 || 342-0545
| IC, ROM, L0 || 342-0545
Line 69: Line 62:
| IC, ROM, H3 || 342-0552
| IC, ROM, H3 || 342-0552
|}
|}
<ref name="asg" />


'''Eight ROMs in high/low pairs, L0/H0 through L3/H3.''' A board with a different ROM complement is not an NT board: the NTX takes eight differently numbered ROMs (342-0560 to 342-0567, or 342-0711 to 342-0718 on the rev 3 board), and the IIf and IIg take four (076-0860 to 076-0863).<ref name="asg" />
The NT board carries eight ROMs in high and low pairs, L0/H0 to L3/H3. The NTX takes eight differently numbered ROMs (342-0560 to 342-0567, or 342-0711 to 342-0718 on the rev. 3 board), and the IIf and IIg take four (076-0860 to 076-0863).<ref name="asg" />
 
== Ports and Switches ==
 
The NT's rear panel carries, left to right, an '''Apple Desktop Bus connector''', a '''switch bank''', the '''RS-232''' port and the '''LocalTalk/RS-422''' port.<ref name="asg" />


The ADB connector is present on the SC, NT and NTX and was '''removed on the IIf and IIg''', which use a pushbutton switch instead.<ref name="asg" /> Apple's guide documents its presence but describes no function for it, so none is claimed here.
== Ports and switches ==
The rear panel carries, left to right, an Apple Desktop Bus connector, the switches, the RS-232 port and the LocalTalk/RS-422 port. The SC, NT and NTX have the ADB connector; the IIf and IIg do not, and use a pushbutton switch instead. Apple's guide shows the connector but describes no function for it.<ref name="asg" />


{| class="wikitable styled-table" style="width:70%;"
{| class="wikitable styled-table" style="width:70%;"
|+'''RS-422 / LocalTalk — mini DIN-8 male''' (shared with the NTX, IIf, IIg and Personal LaserWriter NT)<ref name="asg" />
|+'''RS-422 / LocalTalk, mini DIN-8 (as on the NTX, IIf, IIg and Personal LaserWriter NT)'''
! Pin !! Signal !! Description
! Pin !! Signal !! Description
|-
|-
Line 86: Line 77:
| 2 || HSKi || Handshake in
| 2 || HSKi || Handshake in
|-
|-
| 3 || TxD− || Transmit data −
| 3 || TxD&minus; || Transmit data &minus;
|-
|-
| 4 || SG || Signal ground
| 4 || SG || Signal ground
|-
|-
| 5 || RxD− || Receive data −
| 5 || RxD&minus; || Receive data &minus;
|-
|-
| 6 || TxD+ || Transmit data +
| 6 || TxD+ || Transmit data +
Line 98: Line 89:
| 8 || RxD+ || Receive data +
| 8 || RxD+ || Receive data +
|}
|}
<ref name="asg" />


{| class="wikitable styled-table" style="width:70%;"
{| class="wikitable styled-table" style="width:70%;"
|+'''RS-232 — DB-25 male'''<ref name="asg" />
|+'''RS-232, DB-25'''
! Pin !! Signal !! Description
! Pin !! Signal !! Description
|-
|-
Line 123: Line 115:
| 22 || RI || Ring indicator
| 22 || RI || Ring indicator
|}
|}
<ref name="asg" />


=== Switch configurations ===
=== Switch configurations ===
 
The NT has two switches:<ref name="asg" />
'''The NT has two switches, not a bank of eight.''' Apple's table is short enough to memorise, and a printer that will not talk to anything is very often simply set to the wrong one:<ref name="asg" />


{| class="wikitable styled-table" style="width:70%;"
{| class="wikitable styled-table" style="width:70%;"
|+'''LaserWriter II NT switch configurations'''<ref name="asg" />
|+'''LaserWriter II NT switch configurations'''
! Communication and command mode !! 1 !! 2
! Communication and command mode !! 1 !! 2
|-
|-
Line 136: Line 128:
| Diablo 630 emulation || Down || Up
| Diablo 630 emulation || Down || Up
|-
|-
| 9600 baud RS-232 & RS-422 || Up || Down
| 9600 baud RS-232 and RS-422 || Up || Down
|-
|-
| 1200 baud RS-232 & RS-422 || Down || Down
| 1200 baud RS-232 and RS-422 || Down || Down
|}
|}
<ref name="asg" />


'''Those are the only two serial rates the NT offers.''' The NTX adds a six-switch bank with separate command-mode and handshaking groups, including a PostScript interactive mode and an HP LaserJet mode; '''the NT has neither'''.<ref name="asg" />
The NTX has a six-switch bank with separate command-mode and handshaking groups, including a PostScript interactive mode and an HP LaserJet mode.<ref name="asg" />
 
Apple's cable for the NT is the '''LocalTalk Connector Kit, DIN-8''', service part 590-0338 or 630-8275, Apple model '''M2068''' — the same kit used by the NTX, IIf, IIg and Personal LaserWriter NT.<ref name="asg" />


== Print Engine ==
Apple's cable for the NT is the LocalTalk Connector Kit, DIN-8, service part 590-0338 or 630-8275, model M2068, the same kit as for the NTX, IIf, IIg and Personal LaserWriter NT.<ref name="asg" />


== Print engine ==
{| class="wikitable styled-table" style="width:90%;"
{| class="wikitable styled-table" style="width:90%;"
|+'''LaserWriter II print engine specifications'''<ref name="asg" />
|+'''LaserWriter II print engine specifications'''
| '''Marking engine''' || Canon LBP-SX laser xerographic
| Marking engine || Canon LBP-SX laser xerographic
|-
|-
| '''Print resolution''' || 300 dots per inch
| Print resolution || 300 dots per inch
|-
|-
| '''Speed''' || 8 pages per minute
| Speed || 8 pages per minute
|-
|-
| '''Print materials''' || Letter, legal, A4 and B5 sizes use '''16–20 lb''' single-sheet photocopy bond, '''8–34 lb''' letterhead and coloured stock, or transparency overhead film. Envelopes, labels and paper up to '''36 lb''' via manual feed; envelopes also via an optional envelope tray
| Print materials || Letter, legal, A4 and B5 in 16-20 lb single-sheet photocopy bond, 8-34 lb letterhead and coloured stock, or overhead transparency film. Envelopes, labels and paper up to 36 lb by manual feed; envelopes also from an optional envelope tray
|-
|-
| '''Print capacities''' || '''Paper cassettes hold 200 sheets of 20-lb paper. Envelope cassette holds 15 envelopes'''
| Print capacities || Paper cassettes hold 200 sheets of 20 lb paper; the envelope cassette holds 15 envelopes
|-
|-
| '''Printable surface''' || Letter 8.0 × 10.5 in.; Legal 8.0 × 13.0 in.; A4 7.41 × 10.86 in.; B5 7.69 × 10.16 in.
| Printable surface || Letter 8.0 &times; 10.5 in; Legal 8.0 &times; 13.0 in; A4 7.41 &times; 10.86 in; B5 7.69 &times; 10.16 in
|-
|-
| '''Physical dimensions''' || Height '''8.6 in. (21.8 cm)'''; width '''20 in. (50.8 cm)'''; depth '''18.5 in. (47 cm)'''; weight '''45 lb (20.25 kg)'''
| Physical dimensions || Height 8.6 in (21.8 cm); width 20 in (50.8 cm); depth 18.5 in (47 cm); weight 45 lb (20.25 kg)
|-
|-
| '''Operating environment''' || 50 to 90 °F (10 to 32.5 °C); humidity 20% to 80%
| Operating environment || 50 to 90&nbsp;&deg;F (10 to 32.5&nbsp;&deg;C); humidity 20% to 80%
|-
|-
| '''Power requirements''' || '''90 to 126 volts AC; 50 to 60 Hz'''
| Power requirements || 90 to 126 V AC; 50 to 60 Hz
|}
|}
 
<ref name="asg" />
'''The cassette holds 200 sheets, not 250.''' Apple's guide gives '''no''' wattage, current draw, BTU figure, acoustic noise level, rated engine life, monthly duty cycle or first-page-out time for the LaserWriter II, and none is stated here.


=== The four subsystems ===
=== The four subsystems ===
 
Apple's service course divides the engine into four subsystems:<ref name="train" />
Apple's service course splits the engine into four, and the split is the fastest way to localise a fault:<ref name="train" />
* Power distribution: the AC inlet and power switch, the AC driver board and fuser heater, the DC power supply/motor driver PCA, the high-voltage power supply for the primary corona, transfer corona and developing bias, and the distribution PCA.
 
* Control: the DC controller PCB, which receives the print command from the controller-I/O board, controls the rest of the engine and reports status on the front-panel LEDs. The course tells technicians always to check the DC controller, because a module that seems faulty may not have received its command or its supply.
* '''Power distribution''' — the AC inlet and power switch, the AC driver board and fuser heater, the DC power supply/motor driver PCA, the high-voltage power supply feeding the primary corona, transfer corona and developing bias, and the distribution PCA.
* Image formation: the laser diode, scanning motor and optical fibre, the photosensitive drum, the coronas, the static-charge eliminator, the toner sensor and the fuser.
* '''Control''' — the '''DC controller PCB''', which receives the print command from the controller-I/O board, drives everything else and reports engine status on the front-panel LEDs. Apple's advice is explicit: always check the DC controller as part of troubleshooting, because a module that looks faulty may simply never have received its command or its supply.
* Pickup and feed: the cassette, the pickup and registration rollers, their solenoids and the paper sensors.
* '''Image formation''' — laser diode, scanning motor and optical fibre, photosensitive drum, coronas, static-charge eliminator, toner sensor and fuser.
* '''Pickup/feed''' — cassette, pickup and registration rollers, their solenoids and the paper sensors.


=== Sensors, switches and solenoids ===
=== Sensors, switches and solenoids ===
Real designators, for probing rather than guessing:<ref name="train" />
{| class="wikitable styled-table" style="width:85%;"
{| class="wikitable styled-table" style="width:85%;"
! Designator !! Where !! What it does
|+'''Pickup/feed and control devices (service course)'''
! Designator !! Location !! Function
|-
|-
| '''PS301''' || Distribution PCA || Paper-out sensor — senses paper in the cassette
| PS301 || Distribution PCA || Paper-out sensor; senses paper in the cassette
|-
|-
| '''PS302''' || Distribution PCA || Manual feed sensor — '''shares its arm with PS301'''
| PS302 || Distribution PCA || Manual feed sensor; uses the same arm as PS301
|-
|-
| '''PS331''' || Fuser PCA / fuser assembly PCA || Paper delivery sensor. Paper that fails to reach and clear it in time '''is''' the jam
| PS331 || Fuser PCA or fuser assembly PCA || Paper delivery sensor. If paper fails to reach and clear it in time, a jam is reported
|-
|-
| '''SL301''' || Distribution PCA || Pickup roller solenoid — engages the clutch that turns the pickup roller
| SL301 || Distribution PCA || Pickup roller solenoid; engages the clutch that turns the pickup roller
|-
|-
| '''SL302''' || Distribution PCA || Registration roller clutch solenoid — feeds paper towards the drum
| SL302 || Distribution PCA || Registration roller clutch solenoid
|-
|-
| '''SW301, SW302''' || Distribution PCA || Drum-sensitivity switches, read from the cams on the toner cartridge so the DC controller can match laser intensity to the drum
| SW301, SW302 || Distribution PCA || Drum-sensitivity switches, set by the toner cartridge
|-
|-
| Interlock switch || Top of the DC power supply || Cuts power when the upper unit opens; the interlock lever presses it when the unit closes
| Interlock switch || Top of the DC power supply || Cuts power when the upper unit opens
|}
|}
<ref name="train" />


Two of those explain faults that are otherwise baffling. '''PS301 and PS302 share one arm''', so a bent or sticking arm can produce a paper-out indication and a manual-feed fault at once. And a jam reported with no paper in the machine is normally '''PS331''' or its timing, not the paper path.
Because PS301 and PS302 share one arm, a bent or sticking arm can affect both the paper-out and the manual-feed indications.<ref name="train" />


== Safety ==
== Safety ==
 
The LaserWriter family safety rules apply:<ref name="asg" />
The LaserWriter family safety rules apply in full:<ref name="asg" />
* Switch off and disconnect the power cord before servicing. Parts are live under power; never work on the printer under power except when making live adjustments. With the covers off and the power on, do not touch the high-voltage power supply, the DC power supply or the power supply block.
 
* Do not disconnect the optical fibre cable with the printer on. It carries the infrared laser beam, which cannot be seen and can permanently damage the eyes. Keep screwdrivers and other shiny objects out of the beam path; the reflection is equally dangerous. The warning labels inside the covers read "DANGER - INVISIBLE LASER RADIATION WHEN OPEN. AVOID DIRECT EXPOSURE TO BEAM."
* '''High voltage.''' Switch off and disconnect the AC power cord before servicing. Certain parts are electrified under power. Never work on the printer under power '''except when making live adjustments'''.
* The fuser rollers become very hot. Switch off for at least five minutes before servicing them.
* '''Laser.''' '''Do not disconnect the optical fibre cable when the printer is powered on.''' The fibre carries the infrared laser beam, '''which you cannot see but which can permanently damage your eyes'''. When servicing the optical system, do not put screwdrivers or other shiny objects in the beam path — the reflected beam is equally dangerous. Apple's own warning labels inside the covers read "DANGER — INVISIBLE LASER RADIATION WHEN OPEN. AVOID DIRECT EXPOSURE TO BEAM."
* Do not be grounded when working on plugged-in equipment or making live adjustments, and remove all jewellery first.
* '''Fuser.''' The fuser rollers become very hot. '''Switch off for at least five minutes''' before servicing them.
* The controller-I/O board contains CMOS parts; handle chips, ROMs and SIMMs by their edges.
* '''Do not touch''', with covers off and power on: the high-voltage power supply, the DC power supply, or '''the power supply block''', which is the LaserWriter II-specific item on Apple's list.
* The printer weighs 45 lb.
* '''Do not be grounded''' when working on plugged-in equipment or making live adjustments, and '''remove all jewellery before you start'''.
* Toner is non-toxic (plastic, iron and a little pigment). Remove it with a dry tissue and wash with cold water; hot water makes it gel and fuse into fabric. Toner attacks vinyl.
* '''ESD.''' The controller-I/O board contains CMOS parts, and CMOS chips, ROMs and SIMMs are very susceptible to electrostatic discharge and skin acid. '''Handle them by the edges only.'''
* Never use an ammonia-based cleaner on the LaserWriter II; it discolours the plastic.
* '''Weight.''' 45 lb. Apple warns about lifting LaserWriters for good reason.
* '''Toner''' is non-toxic — plastic, iron and a little pigment. Remove as much as possible with a dry tissue, then wash with '''cold''' water; hot water gels it and fuses it permanently into fabric. '''Toner attacks vinyl.'''
* '''Never use an ammonia-based cleaner on the LaserWriter II''' — it discolours the plastic.


== Status LEDs ==
== Status LEDs ==
 
The LaserWriter II has four status LEDs, all on the front panel.<ref name="asg" /><ref name="train" />
'''There are four, all on the front panel, and none of them is a "Service" light.'''<ref name="asg" /><ref name="train" />


{| class="wikitable styled-table" style="width:92%;"
{| class="wikitable styled-table" style="width:92%;"
|+'''LaserWriter II status LEDs'''<ref name="asg" />
|+'''LaserWriter II status LEDs'''
! LED !! Colour !! Behaviour
! LED !! Colour !! Behaviour
|-
|-
| '''Ready''' || Green || Flashes during warm-up and while the printer is operating. Steady when warmed up and ready. '''Off''' when the printer is not ready, an error condition exists, or the top cover is open
| Ready || Green || Flashes during warm-up and while printing; steady when ready; off when the printer is not ready, an error exists or the top cover is open
|-
|-
| '''Low-Toner''' || '''Orange''' || On and steady when the toner cartridge needs replacement. '''Flashes when the cartridge is installed incorrectly'''
| Low-Toner || Orange || Steady when the toner cartridge needs replacing; flashes when the cartridge is installed incorrectly
|-
|-
| '''Paper-Out''' || '''Red''' || On and steady when out of paper or the paper tray is missing. '''Flashes when the printer is ready to accept manually fed paper'''
| Paper-Out || Red || Steady when out of paper or the paper tray is missing; flashes when the printer is ready for a manually fed sheet
|-
|-
| '''Paper Jam''' || Red || Comes on when paper jams and stays on until the jam is cleared
| Paper Jam || Red || On when paper jams, until the jam is cleared
|}
|}
<ref name="asg" />


'''The error indication is a combination, not a light of its own:'''<ref name="asg" />
When the Paper-Out and Paper Jam lights flash together, the controller-I/O board or the print engine has an error condition.<ref name="asg" />
 
> When both the red '''Paper-Out''' and '''Paper Jam''' lights flash, the controller-I/O board or the print engine has an error condition.


=== Things that are not faults ===
=== Things that are not faults ===
* After a new toner cartridge is fitted, the NT's Low-Toner LED stays on until the printer produces a printout or is switched off and on again.<ref name="asg" />
* A flashing Low-Toner LED means the cartridge is seated wrongly.<ref name="asg" />
* A flashing Paper-Out LED means the printer is waiting for a hand-fed sheet.<ref name="asg" />


* '''A new toner cartridge that leaves the Low-Toner LED on.''' Apple documents this for the NT specifically: after a new cartridge goes in, the Low-Toner LED '''stays lit until the printer produces a printout, or until you switch it off and on again'''.<ref name="asg" />
== Test pages ==
* '''A flashing Low-Toner LED''' means the cartridge is seated wrongly, not that it is empty.
The engine self-test page checks the print engine alone. Press the engine self-test switch on the side of the printer, behind the access cover; no computer or network is involved.<ref name="asg" />
* '''A flashing Paper-Out LED''' means the printer is waiting for you to hand-feed a sheet.
* '''The Ready LED going off''' is how the printer reports trouble — there is no separate service lamp to look for.
 
== Test Pages ==
 
Two pages, testing the two halves of the machine. Knowing which is which halves the diagnostic problem immediately.<ref name="asg" />
 
=== Engine self-test page — tests the print engine ===
'''Press the engine self-test switch, located on the side of the printer behind the access cover.'''<ref name="asg" /> This runs the '''print engine alone''' — no computer, no network, no driver — and is how you isolate engine failures from controller-I/O board failures.


=== Startup test page — tests the controller-I/O board ===
The NT prints a startup test page every time it is switched on, unless this has been turned off with PostScript software or with the LaserWriter Utility on the LaserWriter II Installation disk. It confirms that the controller-I/O board works and shows the page count.<ref name="asg" />
The NT generates a startup test page '''every time it is switched on''', unless the user has switched the function off with PostScript software or with the LaserWriter Utility on the LaserWriter II Installation disk.<ref name="asg" /> It confirms the controller-I/O board and carries the page count.


'''So: a fault on the engine self-test page is in the engine. A machine that prints a clean engine self-test but no startup test page has a controller-I/O board fault. A machine that passes both but will not print from the Macintosh has a cable, switch-setting, driver or host problem''' — and on an NT, check the two-position switch before anything else.
A fault on the engine self-test page is in the engine. A printer that gives a clean self-test page but no startup page points to the controller-I/O board; one that passes both but will not print from a computer points to the cable, the switch settings, the driver or the host.<ref name="asg" />


== Troubleshooting ==
== Troubleshooting ==
=== Pre-power-on checklist ===
=== Pre-power-on checklist ===
Apple's list, to be worked through before the flowcharts:<ref name="asg" />
Apple's list, to work through before the flowcharts:<ref name="asg" />
 
* Line voltage 115 V AC &plusmn;10%
* Line voltage is OK — '''115 volts AC ±10%'''
* Printer on a solid, level surface
* Printer is on a solid, level surface
* Room temperature 50-90&nbsp;&deg;F (10-32.5&nbsp;&deg;C), humidity 20% to 80%
* Room temperature '''50–90 °F (10–32.5 °C)''', humidity 20%–80%
* Not in a hot, humid or dusty place or near open flames
* Not in a hot, humid or dusty area, nor near open flames
* Printer not exposed to ammonia gas
* '''Printer is not exposed to ammonia gas'''
* Out of direct sunlight and well ventilated
* Not in direct sunlight; well ventilated
* Cables and connectors OK
* Cables and connectors are OK
* Toner cartridge installed and containing toner
* Toner cartridge installed and has toner
* Fuser roller cleaner felt in place and not dirty
* '''Fuser roller cleaner felt is in place and not dirty'''
* Print density dial set correctly
* Print density adjustment dial set correctly
* Paper cassette properly loaded and paper within specification
* Paper cassette properly loaded and paper within specification
* '''Transfer corona wire clean and unbroken'''
* Transfer corona wire clean and unbroken
* '''I/O PCA DIP switches are set correctly'''
* I/O PCA DIP switches set correctly
 
The ammonia item is not a curiosity — diazo copiers and some cleaning products produce it, and it will degrade the machine.


=== Troubleshooting order ===
=== Troubleshooting order ===
Apple's sequence is fixed: check the pre-power-on list; be familiar with the safety section before any live electrical check; '''for an SC or NT/NTX begin with Troubleshooting Flowchart 1''' and proceed function by function until every main function is verified; '''if you replace a module and the problem remains, reinstall the original before proceeding'''; and perform preventive maintenance before returning the printer.<ref name="asg" />
Apple's sequence is: work through the pre-power-on list; read the safety section before any live electrical check; for an SC or NT/NTX, start with Troubleshooting Flowchart 1 and continue function by function until every main function is verified; if a replacement module does not cure the fault, refit the original before going on; and carry out preventive maintenance before returning the printer.<ref name="asg" /> The status-LED diagnostic with the rotary switch and the LaserWriter II Test Connector applies only to the IIf and IIg.<ref name="asg" />
 
'''The IIf/IIg status-LED diagnostic does not apply to the NT.''' That procedure — rear rotary switch to 4, LaserWriter II Test Connector on the DB-25 port, read the LEDs against a table — exists only on the IIf and IIg.<ref name="asg" />


=== Laser power output check ===
=== Laser power output check ===
Apple's procedure, which needs a laser power checker and a digital multimeter. '''The check figure is 17.6 mV ± 1.6 mV.'''<ref name="asg" />
This needs a laser power checker and a digital multimeter. The correct reading is 17.6 mV &plusmn;1.6 mV.<ref name="asg" />
 
# Put the printer on a grounded workbench pad and remove the controller-I/O board and the cover set.
# Put the printer on a grounded workbench pad and remove the controller-I/O board and the cover set.
# '''With the power off''', open the laser access hatch on the laser/scanner assembly.
# With the power off, open the laser access hatch on the laser/scanner assembly.
# Insert the laser power checker into the hatch with the detector facing the laser diode.
# Insert the laser power checker with the detector facing the laser diode.
# Black lead to the meter's "Common" socket, red lead to "Volts"; set the meter to volts, '''200 mV range'''.
# Connect the black lead to the meter's common socket and the red lead to volts; set the meter to the 200 mV range.
# Defeat the top cover interlock switch with a '''nonmetallic''' tool, switch on and wait one minute for warm-up.
# Defeat the top cover interlock switch with a nonmetallic tool, switch on and wait one minute for warm-up.
# Depress drum-sensitivity switches '''SW301 and SW302''' below the top cover interlock switch, and press the service test print button.
# Depress drum-sensitivity switches SW301 and SW302, below the top cover interlock switch, and press the service test print button.
# Read the meter. '''17.6 mV ± 1.6 mV.'''
# Read the meter: 17.6 mV &plusmn;1.6 mV.
 
If the power cannot be measured at all, Apple's order is to replace the '''laser/scanner assembly''' and repeat, and if it still cannot be measured, the '''DC controller PCA'''.<ref name="asg" /> Note that this procedure defeats the cover interlock deliberately: the laser is running with the covers off, and the safety rules above apply at their strictest.


== Preventive Maintenance ==
If no power can be measured, Apple's order is to replace the laser/scanner assembly and repeat, then the DC controller PCA.<ref name="asg" /> The procedure runs the laser with the covers off and the interlock defeated.


=== Before starting ===
== Preventive maintenance ==
Power off and unplug; '''let the fuser assembly rollers cool'''; prepare the work area for ESD; spread a drop cloth against grease and spilled toner.<ref name="asg" />
Before starting, switch off and unplug, let the fuser rollers cool, take ESD precautions and lay a drop cloth against grease and toner.<ref name="asg" />


=== Page count ===
=== Page count ===
Switch on and wait for the startup test page. The number at the bottom is the pages printed '''since the controller-I/O board was installed''' — accurate only if that board has never been repaired or upgraded. If it has, Apple's instruction is to check the '''Repair Log Label on the bottom of the printer''' and ask the customer.<ref name="asg" />
The number at the bottom of the startup test page is the pages printed since the controller-I/O board was installed. If the board has been replaced or upgraded, Apple's instruction is to check the Repair Log Label on the bottom of the printer and ask the customer.<ref name="asg" />


=== Apple's parts replacement schedule ===
=== Apple's parts replacement schedule ===
'''Every 50,000 prints:''' replace the '''ozone filter''' and check the fan.<ref name="asg" />
Every 50,000 prints, replace the ozone filter and check the fan. Every 100,000 prints, replace the fuser assembly, the transfer guide assembly, the preconditioning exposure assembly, the paper feed roller assembly and the transfer corona assembly.<ref name="asg" />
 
'''Every 100,000 prints,''' replace:<ref name="asg" />
* Fuser assembly
* Transfer guide assembly
* Preconditioning exposure assembly
* Paper feed roller assembly
* Transfer corona assembly
 
'''That is the whole schedule.''' Apple's guide has no monthly, annual-by-page-count or 200,000/300,000-print item for this machine, and the ozone filter — a genuine consumable that is very often never changed — is the one most worth acting on.


=== Cleaning ===
=== Cleaning ===
{| class="wikitable styled-table" style="width:80%;"
{| class="wikitable styled-table" style="width:80%;"
|+'''Service points and what to use'''<ref name="asg" />
|+'''Service points and cleaning materials'''
! Service point !! Tool or solvent
! Service point !! Tool or solvent
|-
|-
Line 341: Line 299:
| Registration rollers || Cloth dampened with water
| Registration rollers || Cloth dampened with water
|}
|}
<ref name="asg" />


Apple splits these into items the customer cleans as needed (the first five) and a dealer list to be done '''every 12 months or at each service call''' (all ten).<ref name="asg" /> Note which points take water and which take alcohol — they are not interchangeable.
The customer cleans the first five items as needed; the dealer cleans all ten every 12 months or at each service call.<ref name="asg" />


== Parts ==
== Parts ==
Selected entries, common to the LaserWriter II range except where the NT is named:<ref name="asg" />
Selected entries, common to the LaserWriter II range except where the NT is named:<ref name="asg" />


Line 351: Line 309:
! Part !! Number
! Part !! Number
|-
|-
| '''Controller-I/O Board, LW II NT''' || '''661-0438'''
| Controller-I/O board, LW II NT || 661-0438
|-
|-
| DC Controller PCA || 661-0426
| DC controller PCA || 661-0426
|-
|-
| DC Power Supply, 110/115 V || 661-0424
| DC power supply, 110/115 V || 661-0424
|-
|-
| DC Power Supply, 220/240 V || 661-0442
| DC power supply, 220/240 V || 661-0442
|-
|-
| Fuse, 125 V 6.3 A || 941-0005
| Fuse, 125 V 6.3 A || 941-0005
Line 363: Line 321:
| Fuse, medium time lag 3.15 A, 250 V || 740-0061
| Fuse, medium time lag 3.15 A, 250 V || 740-0061
|-
|-
| High-Voltage Power Supply || 661-0425
| High-voltage power supply || 661-0425
|-
|-
| Laser/Scanner Assembly || 661-0423
| Laser/scanner assembly || 661-0423
|-
|-
| '''Fuser Assembly, 110/115 V''' || 661-0440
| Fuser assembly, 110/115 V || 661-0440
|-
|-
| '''Fuser Assembly, 220/240 V''' || 661-0444
| Fuser assembly, 220/240 V || 661-0444
|-
|-
| Fuser Heater, 100 V, '''620 W''' || 938-0003
| Fuser heater, 100 V, 620 W || 938-0003
|-
|-
| Fuser Heater, 220 V, '''570 W''' || 938-0004
| Fuser heater, 220 V, 570 W || 938-0004
|-
|-
| Fuser Roller Cleaner || 970-0049
| Fuser roller cleaner || 970-0049
|-
|-
| '''Ozone Filter''' || 961-0003
| Ozone filter || 961-0003
|-
|-
| Ozone Filter (for case with door) || 961-0007
| Ozone filter (for case with door) || 961-0007
|-
|-
| Power Supply Block, 110/115 V || 661-0427
| Power supply block, 110/115 V || 661-0427
|-
|-
| Power Supply Block, 220/240 V || 661-0443
| Power supply block, 220/240 V || 661-0443
|-
|-
| Distribution PCA || 971-0028
| Distribution PCA || 971-0028
|-
|-
| Transfer Corona Assembly || 971-0026
| Transfer corona assembly || 971-0026
|-
|-
| Transfer Guide Assembly || 971-0019
| Transfer guide assembly || 971-0019
|-
|-
| Paper Feed Roller Assembly || 971-0017
| Paper feed roller assembly || 971-0017
|-
|-
| Feeder Assembly || 971-0018
| Feeder assembly || 971-0018
|-
|-
| Delivery Assembly || 971-0023
| Delivery assembly || 971-0023
|-
|-
| Main Motor Assembly || 971-0014
| Main motor assembly || 971-0014
|-
|-
| Fan, Lower || 959-0021
| Fan, lower || 959-0021
|-
|-
| Fan, Upper || 959-0022
| Fan, upper || 959-0022
|-
|-
| Status Panel || 971-0005
| Status panel || 971-0005
|-
|-
| Cleaning Brush || 970-0047
| Cleaning brush || 970-0047
|-
|-
| Mirror Assembly || 971-0007
| Mirror assembly || 971-0007
|}
|}


The DC power supply, fuser assembly, fuser heater and power supply block are '''different parts for 110 V and 220 V machines'''.<ref name="asg" /> The fuser heaters differ in wattage as well as voltage — 620 W at 100 V, 570 W at 220 V.
The DC power supply, fuser assembly, fuser heater and power supply block are different parts for 110 V and 220 V machines, and the two fuser heaters are rated 620 W at 100 V and 570 W at 220 V.<ref name="asg" />


== Service Manuals ==
== Service manuals ==
<pdf>File:Apple LaserWriter Printers Volume I.pdf</pdf>
<pdf>File:Apple LaserWriter Printers Volume I.pdf</pdf>


<pdf>File:Apple LaserWriter II Service Training Participant Manual Version 1.1 Oct 1992.pdf</pdf>
<pdf>File:Apple LaserWriter II Service Training Participant Manual Version 1.1 Oct 1992.pdf</pdf>


== See Also ==
== Related pages ==
* [[Apple LaserWriter II SC]]
* [[Apple LaserWriter II SC]]
* [[Apple LaserWriter]]
* [[Apple LaserWriter]]
Line 425: Line 383:


== References ==
== References ==
<references />
<references />


Latest revision as of 14:44, 30 September 2026

Apple LaserWriter II NT
Apple LaserWriter II (the NT, SC and NTX share this case)
Manufacturer Apple Computer, Inc.
Type Laser printer
Interface LocalTalk / RS-422 (mini DIN-8); RS-232 (DB-25); Apple Desktop Bus connector present
Compatible Macintosh; other computers over RS-232
Dimensions 8.6 in high × 20 in wide × 18.5 in deep
Weight 45 lb (20.25 kg)
Power 90-126 V AC, 50-60 Hz
Part number 661-0438 (NT controller-I/O board)

The Apple LaserWriter II NT is the PostScript member of the LaserWriter II range. It shares the Canon LBP-SX engine, the case, the power supply and the mechanical parts with the II SC and the NTX. Its controller-I/O board has a 68000 at 11.16 MHz, 1.0 MB of ROM and 2.0 MB of RAM, and runs PostScript and Diablo 630 emulation over LocalTalk, RS-232 and RS-422.[1] Read the Safety section before taking the covers off: the printer contains an invisible laser, a fuser that needs five minutes to cool, and a high-voltage supply for the coronas.

Controller-I/O board

[edit | edit source]
Controller-I/O board specifications, LaserWriter II range
SC NT NTX IIf IIg
CPU 68000 (7.45 MHz) 68000 (11.16 MHz) 68020 (16.67 MHz) 68030 (20.0 MHz) 68030 (25.0 MHz)
ROM 16 KB 1.0 MB 1.0 MB 2.0 MB 2.0 MB
RAM 1.0 MB 2.0 MB 2.0 MB, expandable to 12 MB 2.0 MB, expandable to 32 MB 5.0 MB, expandable to 32 MB
I/O SCSI LocalTalk, RS-232, RS-422 LocalTalk, RS-232, RS-422, SCSI LocalTalk, RS-232, RS-422, SCSI LocalTalk, RS-232, RS-422, SCSI, Ethernet
Imaging languages QuickDraw PostScript, Diablo 630 PostScript, Diablo 630, HP LaserJet PostScript Level 1 and 2, HP LaserJet IIP PostScript Level 1 and 2, HP LaserJet IIP
Built-in fonts Times, Helvetica, Courier, Symbol Times, Courier, Symbol, Palatino, Helvetica, Helvetica Narrow, ITC Bookman, ITC Avant Garde, ITC Zapf Chancery, New Century Schoolbook, ITC Zapf Dingbats As NT As NT As NT

[1]

Apple's guide gives memory upgrade procedures for the NTX and the IIf/IIg, and none for the NT, whose 2.0 MB is fixed.[1]

Board layout

[edit | edit source]

Apple's service course diagram of the NT controller-I/O board shows an MC68000, a 6532, an 8530 SCC, 1 MB of ROM, 2 MB of RAM and SRAMs, with the Apple Desktop Bus connector, a two-position switch, the RS-232 port and the LocalTalk/RS-422 port along the back panel. The board connects to the print engine through a 32-pin right-angle connector that engages as the board slides into its guide rails.[2]

Board and ROM part numbers

[edit | edit source]
NT controller-I/O board
Part Number
Controller-I/O board, LW II NT 661-0438
IC, ROM, L0 342-0545
IC, ROM, H0 342-0546
IC, ROM, L1 342-0547
IC, ROM, H1 342-0548
IC, ROM, L2 342-0549
IC, ROM, H2 342-0550
IC, ROM, L3 342-0551
IC, ROM, H3 342-0552

[1]

The NT board carries eight ROMs in high and low pairs, L0/H0 to L3/H3. The NTX takes eight differently numbered ROMs (342-0560 to 342-0567, or 342-0711 to 342-0718 on the rev. 3 board), and the IIf and IIg take four (076-0860 to 076-0863).[1]

Ports and switches

[edit | edit source]

The rear panel carries, left to right, an Apple Desktop Bus connector, the switches, the RS-232 port and the LocalTalk/RS-422 port. The SC, NT and NTX have the ADB connector; the IIf and IIg do not, and use a pushbutton switch instead. Apple's guide shows the connector but describes no function for it.[1]

RS-422 / LocalTalk, mini DIN-8 (as on the NTX, IIf, IIg and Personal LaserWriter NT)
Pin Signal Description
1 HSKo Handshake out
2 HSKi Handshake in
3 TxD− Transmit data −
4 SG Signal ground
5 RxD− Receive data −
6 TxD+ Transmit data +
7 GPi General-purpose input
8 RxD+ Receive data +

[1]

RS-232, DB-25
Pin Signal Description
1 SGND Signal ground
2 TxD Transmitted data
3 RxD Received data
4 RTS Request to send
5 CTS Clear to send
6 DSR Data set ready
7 SG Signal ground
8 DCD Data carrier detect
20 DTR Data terminal ready
22 RI Ring indicator

[1]

Switch configurations

[edit | edit source]

The NT has two switches:[1]

LaserWriter II NT switch configurations
Communication and command mode 1 2
LocalTalk Up Up
Diablo 630 emulation Down Up
9600 baud RS-232 and RS-422 Up Down
1200 baud RS-232 and RS-422 Down Down

[1]

The NTX has a six-switch bank with separate command-mode and handshaking groups, including a PostScript interactive mode and an HP LaserJet mode.[1]

Apple's cable for the NT is the LocalTalk Connector Kit, DIN-8, service part 590-0338 or 630-8275, model M2068, the same kit as for the NTX, IIf, IIg and Personal LaserWriter NT.[1]

[edit | edit source]
LaserWriter II print engine specifications
Marking engine Canon LBP-SX laser xerographic
Print resolution 300 dots per inch
Speed 8 pages per minute
Print materials Letter, legal, A4 and B5 in 16-20 lb single-sheet photocopy bond, 8-34 lb letterhead and coloured stock, or overhead transparency film. Envelopes, labels and paper up to 36 lb by manual feed; envelopes also from an optional envelope tray
Print capacities Paper cassettes hold 200 sheets of 20 lb paper; the envelope cassette holds 15 envelopes
Printable surface Letter 8.0 × 10.5 in; Legal 8.0 × 13.0 in; A4 7.41 × 10.86 in; B5 7.69 × 10.16 in
Physical dimensions Height 8.6 in (21.8 cm); width 20 in (50.8 cm); depth 18.5 in (47 cm); weight 45 lb (20.25 kg)
Operating environment 50 to 90 °F (10 to 32.5 °C); humidity 20% to 80%
Power requirements 90 to 126 V AC; 50 to 60 Hz

[1]

The four subsystems

[edit | edit source]

Apple's service course divides the engine into four subsystems:[2]

  • Power distribution: the AC inlet and power switch, the AC driver board and fuser heater, the DC power supply/motor driver PCA, the high-voltage power supply for the primary corona, transfer corona and developing bias, and the distribution PCA.
  • Control: the DC controller PCB, which receives the print command from the controller-I/O board, controls the rest of the engine and reports status on the front-panel LEDs. The course tells technicians always to check the DC controller, because a module that seems faulty may not have received its command or its supply.
  • Image formation: the laser diode, scanning motor and optical fibre, the photosensitive drum, the coronas, the static-charge eliminator, the toner sensor and the fuser.
  • Pickup and feed: the cassette, the pickup and registration rollers, their solenoids and the paper sensors.

Sensors, switches and solenoids

[edit | edit source]
Pickup/feed and control devices (service course)
Designator Location Function
PS301 Distribution PCA Paper-out sensor; senses paper in the cassette
PS302 Distribution PCA Manual feed sensor; uses the same arm as PS301
PS331 Fuser PCA or fuser assembly PCA Paper delivery sensor. If paper fails to reach and clear it in time, a jam is reported
SL301 Distribution PCA Pickup roller solenoid; engages the clutch that turns the pickup roller
SL302 Distribution PCA Registration roller clutch solenoid
SW301, SW302 Distribution PCA Drum-sensitivity switches, set by the toner cartridge
Interlock switch Top of the DC power supply Cuts power when the upper unit opens

[2]

Because PS301 and PS302 share one arm, a bent or sticking arm can affect both the paper-out and the manual-feed indications.[2]

Safety

[edit | edit source]

The LaserWriter family safety rules apply:[1]

  • Switch off and disconnect the power cord before servicing. Parts are live under power; never work on the printer under power except when making live adjustments. With the covers off and the power on, do not touch the high-voltage power supply, the DC power supply or the power supply block.
  • Do not disconnect the optical fibre cable with the printer on. It carries the infrared laser beam, which cannot be seen and can permanently damage the eyes. Keep screwdrivers and other shiny objects out of the beam path; the reflection is equally dangerous. The warning labels inside the covers read "DANGER - INVISIBLE LASER RADIATION WHEN OPEN. AVOID DIRECT EXPOSURE TO BEAM."
  • The fuser rollers become very hot. Switch off for at least five minutes before servicing them.
  • Do not be grounded when working on plugged-in equipment or making live adjustments, and remove all jewellery first.
  • The controller-I/O board contains CMOS parts; handle chips, ROMs and SIMMs by their edges.
  • The printer weighs 45 lb.
  • Toner is non-toxic (plastic, iron and a little pigment). Remove it with a dry tissue and wash with cold water; hot water makes it gel and fuse into fabric. Toner attacks vinyl.
  • Never use an ammonia-based cleaner on the LaserWriter II; it discolours the plastic.

Status LEDs

[edit | edit source]

The LaserWriter II has four status LEDs, all on the front panel.[1][2]

LaserWriter II status LEDs
LED Colour Behaviour
Ready Green Flashes during warm-up and while printing; steady when ready; off when the printer is not ready, an error exists or the top cover is open
Low-Toner Orange Steady when the toner cartridge needs replacing; flashes when the cartridge is installed incorrectly
Paper-Out Red Steady when out of paper or the paper tray is missing; flashes when the printer is ready for a manually fed sheet
Paper Jam Red On when paper jams, until the jam is cleared

[1]

When the Paper-Out and Paper Jam lights flash together, the controller-I/O board or the print engine has an error condition.[1]

Things that are not faults

[edit | edit source]
  • After a new toner cartridge is fitted, the NT's Low-Toner LED stays on until the printer produces a printout or is switched off and on again.[1]
  • A flashing Low-Toner LED means the cartridge is seated wrongly.[1]
  • A flashing Paper-Out LED means the printer is waiting for a hand-fed sheet.[1]

Test pages

[edit | edit source]

The engine self-test page checks the print engine alone. Press the engine self-test switch on the side of the printer, behind the access cover; no computer or network is involved.[1]

The NT prints a startup test page every time it is switched on, unless this has been turned off with PostScript software or with the LaserWriter Utility on the LaserWriter II Installation disk. It confirms that the controller-I/O board works and shows the page count.[1]

A fault on the engine self-test page is in the engine. A printer that gives a clean self-test page but no startup page points to the controller-I/O board; one that passes both but will not print from a computer points to the cable, the switch settings, the driver or the host.[1]

Troubleshooting

[edit | edit source]

Pre-power-on checklist

[edit | edit source]

Apple's list, to work through before the flowcharts:[1]

  • Line voltage 115 V AC ±10%
  • Printer on a solid, level surface
  • Room temperature 50-90 °F (10-32.5 °C), humidity 20% to 80%
  • Not in a hot, humid or dusty place or near open flames
  • Printer not exposed to ammonia gas
  • Out of direct sunlight and well ventilated
  • Cables and connectors OK
  • Toner cartridge installed and containing toner
  • Fuser roller cleaner felt in place and not dirty
  • Print density dial set correctly
  • Paper cassette properly loaded and paper within specification
  • Transfer corona wire clean and unbroken
  • I/O PCA DIP switches set correctly

Troubleshooting order

[edit | edit source]

Apple's sequence is: work through the pre-power-on list; read the safety section before any live electrical check; for an SC or NT/NTX, start with Troubleshooting Flowchart 1 and continue function by function until every main function is verified; if a replacement module does not cure the fault, refit the original before going on; and carry out preventive maintenance before returning the printer.[1] The status-LED diagnostic with the rotary switch and the LaserWriter II Test Connector applies only to the IIf and IIg.[1]

Laser power output check

[edit | edit source]

This needs a laser power checker and a digital multimeter. The correct reading is 17.6 mV ±1.6 mV.[1]

  1. Put the printer on a grounded workbench pad and remove the controller-I/O board and the cover set.
  2. With the power off, open the laser access hatch on the laser/scanner assembly.
  3. Insert the laser power checker with the detector facing the laser diode.
  4. Connect the black lead to the meter's common socket and the red lead to volts; set the meter to the 200 mV range.
  5. Defeat the top cover interlock switch with a nonmetallic tool, switch on and wait one minute for warm-up.
  6. Depress drum-sensitivity switches SW301 and SW302, below the top cover interlock switch, and press the service test print button.
  7. Read the meter: 17.6 mV ±1.6 mV.

If no power can be measured, Apple's order is to replace the laser/scanner assembly and repeat, then the DC controller PCA.[1] The procedure runs the laser with the covers off and the interlock defeated.

Preventive maintenance

[edit | edit source]

Before starting, switch off and unplug, let the fuser rollers cool, take ESD precautions and lay a drop cloth against grease and toner.[1]

Page count

[edit | edit source]

The number at the bottom of the startup test page is the pages printed since the controller-I/O board was installed. If the board has been replaced or upgraded, Apple's instruction is to check the Repair Log Label on the bottom of the printer and ask the customer.[1]

Apple's parts replacement schedule

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Every 50,000 prints, replace the ozone filter and check the fan. Every 100,000 prints, replace the fuser assembly, the transfer guide assembly, the preconditioning exposure assembly, the paper feed roller assembly and the transfer corona assembly.[1]

Cleaning

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Service points and cleaning materials
Service point Tool or solvent
Primary corona wire Cleaning brush supplied with the printer
Transfer corona wire Cotton swab (with isopropyl alcohol, for user cleaning)
Transfer guide Cloth dampened with water
Fuser rollers Fuser cleaning pad
Exterior case Cloth dampened with water
Separation claws Cloth dampened with alcohol
Paper guide Cloth dampened with alcohol
Lower delivery guide Cloth dampened with alcohol
Feeder guide Cloth dampened with water
Registration rollers Cloth dampened with water

[1]

The customer cleans the first five items as needed; the dealer cleans all ten every 12 months or at each service call.[1]

Parts

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Selected entries, common to the LaserWriter II range except where the NT is named:[1]

Part Number
Controller-I/O board, LW II NT 661-0438
DC controller PCA 661-0426
DC power supply, 110/115 V 661-0424
DC power supply, 220/240 V 661-0442
Fuse, 125 V 6.3 A 941-0005
Fuse, medium time lag 3.15 A, 250 V 740-0061
High-voltage power supply 661-0425
Laser/scanner assembly 661-0423
Fuser assembly, 110/115 V 661-0440
Fuser assembly, 220/240 V 661-0444
Fuser heater, 100 V, 620 W 938-0003
Fuser heater, 220 V, 570 W 938-0004
Fuser roller cleaner 970-0049
Ozone filter 961-0003
Ozone filter (for case with door) 961-0007
Power supply block, 110/115 V 661-0427
Power supply block, 220/240 V 661-0443
Distribution PCA 971-0028
Transfer corona assembly 971-0026
Transfer guide assembly 971-0019
Paper feed roller assembly 971-0017
Feeder assembly 971-0018
Delivery assembly 971-0023
Main motor assembly 971-0014
Fan, lower 959-0021
Fan, upper 959-0022
Status panel 971-0005
Cleaning brush 970-0047
Mirror assembly 971-0007

The DC power supply, fuser assembly, fuser heater and power supply block are different parts for 110 V and 220 V machines, and the two fuser heaters are rated 620 W at 100 V and 570 W at 220 V.[1]

Service manuals

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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 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.30 1.31 1.32 1.33 1.34 Apple Service Guide for LaserWriter Printers, Volume I, Apple Computer, Inc., January 1992 (072-0631-B), hosted on this wiki as Apple LaserWriter Printers Volume I (PDF). Covers the LaserWriter, LaserWriter Plus, LaserWriter II SC/NT/NTX/IIf/IIg and Personal LaserWriter SC/NT/LS. Introductory safety section: the high-voltage, optical-fibre, fuser-cooling, ESD, not-being-grounded and lifting warnings; the LaserWriter Safety Rules; the toner-safety paragraph; the laser-safety paragraph and the three laser warning labels. Tab 3, LaserWriter II: parts list including the NT controller-I/O board and its ROM set (pages 4-5); controller-I/O board specifications (page 10); print engine specifications (page 11); status LEDs (page 12); test pages (page 13); the pre-power-on checklist, the troubleshooting flowcharts and tables including the NT low-toner note (pages 14-54); the laser power output check (page 55); and preventive maintenance including the page count, the parts replacement schedule and the user and standard maintenance tables (pages 59-60). Tab 6, Ports and Cables: the peripheral cable table, external connector diagrams, the RS-422 and RS-232 pin-outs and the LaserWriter II NT switch configuration table.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Apple Service Training: LaserWriter II Service Course, Participant Manual, Version 1.1, Apple Computer, Inc., October 1992, hosted on this wiki as LaserWriter II Service Course: Participant Manual (PDF). Module 1, "LaserWriter II Parts and Functions": the SC, NT and NTX I/O board block diagrams and back panels (figures 1-3 to 1-5) and the 32-pin right-angle engine connector; the four-subsystem breakdown (power distribution, control, image formation, pickup/feed); the power distribution diagram (figure 1-7); the DC controller PCB's role; the interlock switch at the top of the DC power supply; the status panel description; the distribution PCA (figure 1-12) with drum-sensitivity switches SW301 and SW302, pickup solenoid SL301, registration clutch solenoid SL302, paper-out sensor PS301 and manual feed sensor PS302; and paper delivery sensor PS331 on the fuser PCA.


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