Apple Laserwriter 16.600 Ps Service Manual

K

Service Source

LaserWriter 16/600 PS

LaserWriter 16/600 PS

K

Service Source

Basics

LaserWriter 16/600 PS

Basics Read Me First - 1

Read Me First

The LaserWriter 16/600 PS has the same form factor as
the LaserWriter Pro 600/630, though some functions and
parts are entirely different. If you want a detailed
description of the new servicing issues presented by this
printer, go to the document “New Servicing Issues” that is
included on this CD. Below is a brief outline of this
document.

New rear housing layout

– I/O controller easier to access
– D/C controller harder to access
– New I/O connectivity procedures
– Fax card option
– Internal hard drive option

Basics Read Me First - 2

Faster engine

– Modules not backward-compatible
– Feeders not backward-compatible
– Two new fans for ventilation
– Slightly louder (52 dB vs. 49 dB printing)

New printer utilities

Advanced multi-platform performance

New printer diagnostic

Basics Printer Utilities - 3

Printer Utilities

The printer utility that you use depends on the type of
computer you use. This topic briefly describes the various
utilities. Refer to chapters 3 and 4 of the user’s guide for
complete information

Note:

Settings made with any of these printer utilities
become default parameters and affect all printed documents,
regardless of the computer that originated the print request.

Basics Printer Utilities - 4

Apple Printer Utility for Macintosh Computers

The Apple Printer Utility for Macintosh computers works
only with the LaserWriter 16/600 PS. You use this utility
to set parameters that reside on the printer’s I/O controller
board. You can use this utility to perform many functions,
some of which are listed below.

– Naming the printer
– Initializing SCSI hard drives
– Downloading fonts
– Setting default printer resolution
– Setting default paper-handling options
– Setting default print density
– Printing configuration page
– Turning off the startup test page
– Setting communication protocols

Note:

The LaserWriter Utility for Macintosh computers

Basics Printer Utilities - 5

does not work with the LaserWriter 16/600 PS.

The Apple Printer Utility has a hierarchical interface that
is completely different than the LaserWriter Utility for the
Macintosh that serves other laser printers.

After you launch the Apple Printer Utility and select a
printer, a window opens that shows four headings. These
headings are like folders in the Finder. If you click an
arrow, the folder expands to show more items. The command
“Print Configuration Page” is located in the File menu in
the menu bar.

Basics Printer Utilities - 6

LaserWriter Utility for Windows

The LaserWriter Utility for Windows has the same functions
as the Apple Printer Utility for Macintosh computers,
except for certain hard drive and font functions which are
absent from the Windows printer drive interface.

NetWare Utilities

There are two DOS utilities, LWPMAN and LWFORM, that
perform a subset of Apple Printer Utility functions in a
NetWare environment.

TCP/IP Printer Configuration Utility for UNIX

To configure the printer from a UNIX environment, run the
TCP/IP Printer Configuration Utility by using the Telnet
program.

Basics Paper Path - 7

Paper Path

There are four paper

Optional

*

Standard
Cassette (250)

Optional Sheet
Feeder (500)

Envelope
Feeder (75)

Multipurpose
Tray (100)

sources and one output tray
in a complete system. The
number in parenthesis is
the capacity of the paper
source.

Note:

The asterisk at the
point where the paper paths
meet denotes a synchro­nization pause. See PS602
in “Sensing System Theory”
in this chapter.

Basics Mechanical Drive Theory - 8

Mechanical Drive

M1

M3

M2

M4

Theory

There are four motors and
four separate drive trains in
a complete system. Two are
in the printer engine and one
is in each of the optional
feeders.

• M1 Main Motor

• M2 Pickup Block Motor

• M3 Sheet Feeder Motor

• M4 Envelope Feeder

Motor

Basics Mechanical Drive Theory - 9

M1 Main Motor Drive

Power

Supply

Toner Cartridge

Transfer Roller

DC Controller Board

Connecting Cable

Main Motor

Drive Assembly

D

Fuser Assembly

Gears/Rollers

E

Delivery Roller Assy

Gears/Belt/Rollers

A

The main motor powers the
system that transports
paper from the toner
cartridge to the delivery
tray on top of the printer.

B

Note:

The letters next to the
boxes correspond to the

C

labels in the mechanical
drive animations that are
available on the CD.

F

G

Basics Mechanical Drive Theory - 10

M2 Pickup Block Motor Drive

Power

Supply

DC Controller Board

Connecting Cable

Pickup Controller Board

A

The pickup block motor
powers the system that
transports paper into the
engine, through the pickup

H

block, and up to the toner
cartridge.

Pickup

Solenoids

Pickup Sensor Board

Pickup Block Motor

Gear/Roller System

J

Note:

The DC controller
board does not connect

K

directly to the pickup block
motor. Make sure to
troubleshoot the three
intermediate blocks if there
is a failure in pickup block
drive. Ê

Basics Mechanical Drive Theory - 11

M3 Sheet Feeder Motor Drive

Power

Supply

ENGINE

SHEET FEEDER

DC Controller Board

Connecting Cable

Pickup Controller Board

Connecting Cable

Controller Block

Feeder Controller Board

Sheet Feeder Motor

A

The sheet feeder motor
powers the system that
transports paper from the

H

500-sheet cassette upward
into the printer engine.

Note:

Once the paper

L

reaches the lower feed
roller in the pickup block,

M

engine components supply
mechanical drive.

N

Pickup

Solenoid

Gear/Roller System

Basics Mechanical Drive Theory - 12

Power

Supply

ENGINE

ENV FEEDER

Pickup

Rollers

DC Controller Board

Connecting Cable

Pickup Controller Board

Connecting Cable

Connecting Cable

Feeder Controller Board

Feeder Controller Board

Envelope Feeder Motor

Drive Assembly

Primary Feed Roller

Separation Drive Assy

A

M4 Envelope Feeder Motor Drive

The envelope feeder motor

H

O

P

Q

powers the system that
separates envelopes and
feeds them into the printer
engine.

Note:

Once an envelope
reaches the upper feed
rollers in the pickup block,
engine components supply
mechanical drive.

Basics Sensing System Theory - 13

Sensing System Theory

There are six paper sensors, one dual-purpose sensor, and
seven sensing switches in a LaserWriter 16/600 PS
system:

Paper Sensors

– PS601: Cassette Paper Sensor
– PS602: Registration Paper Sensor
– PS701: Multipurpose Paper-End Sensor
– PS702: Multipurpose Paper-Present Sensor
– PS851: Sheet Feeder Paper-Present Sensor
– PS931: Envelope Paper-Present Sensor
– PS201: Delivery/Interlock Sensor

Sensing Switches

– SW601: Top Cover Interlock Switch
– SW603: Upper Cassette Size Sensing Switch

Basics Sensing System Theory - 14

– •SW604: Upper Cassette Size Sensing Switch
– •SW605: Upper Cassette Size Sensing Switch
– •SW851: Lower Cassette Size Sensing Switch
– •SW852: Lower Cassette Size Sensing Switch
– •SW853: Lower Cassette Size Sensing Switch

Basics Sensing System Theory - 15

Actuator

OPEN

CLOSED

Photointerrupter

Paper Sensors

Paper sensors consist of an
actuator, a U-shaped photo
interrupter, and circuitry.
Sensors are tripped as the
actuator swings against
movement of paper and
blocks the gap of the U. An
actuator can be passive
(governed by gravity) or
spring-loaded.

Note:

Sensor failure can be
either mechanical or
electrical. When
troubleshooting sensors,
first confirm that the arm

Basics Sensing System Theory - 16

or lever moves freely without snagging, that any springs are
applying correct resistance, and that the actuator is not
broken. Then check that all cable connections are secure. If
you have eliminated mechanical issues, proceed with
electrical troubleshooting.

Basics Sensing System Theory - 17

PS601

Cassette Paper Sensor

Actuator: A passive lever in
the sensor holder assembly
is tripped by insertion of a
loaded cassette tray.

Sensor

Holder

Assembly

PS601

Paper

Pickup Block

Basics Sensing System Theory - 18

PS602

Registration Paper Sensor

Actuator: A spring-loaded
lever in the sensor holder
assembly is tripped by
arriving paper.

Sensor

Holder

Assembly

PS602

Paper

Pickup Block

All paper stops at PS602
and waits for proper
synchronization with drum
rotation and mechanical
drive.

Note:

If paper does not
reach sensor PS602 within
the prescribed time after
the pickup signal is issued, a

Basics Sensing System Theory - 19

pickup unit delay jam exists and the controller stops
printing.

If paper reaches the sensor but does not clear it within the
correct time, a pickup unit stationary jam exists. The time
allowed for paper to clear is a function of paper size, which
is detected by PS701 (for manually fed paper) and by
sensing switches (for cassette-fed paper).

Basics Sensing System Theory - 20

PS702

Multipurpose Paper­Present Sensor

Actuator: A spring-loaded
lever in the paper pickup
block is tripped by the

Pickup

Sensor

Board

PS702

Paper

Pickup Block

leading edge of paper as it is
loaded in the multipurpose
tray.

Basics Sensing System Theory - 21

PS701

Multipurpose Paper-End
Sensor

Actuator: A passive lever in
the paper pickup block is
tripped by the trailing edge

Pickup

Sensor

Board

PS701

Paper

Pickup Block

of paper leaving the
multipurpose tray.

Sensor PS701 detects the
size of paper fed from the
multipurpose tray.

Basics Sensing System Theory - 22

PS201

Delivery/Interlock Sensor

Actuator: A plastic tab on
the fuser door and a sensing
lever in the fuser assembly

Delivery/Interlock Sensor

act independently to trip a
photo interrupter.

PS201 detects two things:
paper exiting the fuser and
closure of the fuser door.

Note:

If paper does not
reach sensor PS201 within

5.2 seconds after it reached
registration sensor J602, a
delivery unit delay jam

Basics Sensing System Theory - 23

exists and the controller stops printing.

If paper reaches the sensor but does not clear it within the
correct time, a delivery unit stationary jam exists. The
time allowed for paper to clear is a function of paper size,
which is detected by PS701 (for manually fed paper) and by
sensing switches (for cassette-fed paper).

Basics Sensing System Theory - 24

PS851

Sheet Feeder Paper­Present Sensor

Actuator: A passive lever in
the controller block is
tripped by insertion of a
loaded cassette tray.

PS851

Controller

Block

Basics Sensing System Theory - 25

PS931

Envelope Feeder Paper­Present Sensor

Actuator: A spring-loaded
lever is tripped by
placement of envelopes into
the feeder.

Basics Sensing System Theory - 26

Circuit Board

Leaf Spring

Microswitch

Actuator

Microswitch ON

Microswitch OFF

Sensing Switches

Sensing switches attach to a
circuit board and do not use
photo interrupters.

Switches are actuated by leaf
springs that press inward as
you insert a cassette tray or
close the top cover.

Failure in sensing switches
can be either mechanical or
electrical. When
troubleshooting switches,
first confirm that the
actuator has not broken off
and then confirm that the
leaf springs are not bent or

Basics Sensing System Theory - 27

misshapen. You should be able to press the leaf spring with
your finger and hear the clicking of the microswitch.

If you have eliminated mechanical issues, proceed with
electrical troubleshooting.

Basics Sensing System Theory - 28

SW601

Top Cover Interlock Switch

Actuator: A tab on the top
cover actuates a leaf spring

Cover Interlock Arm

Cover Interlock Spring

Cover Interlock Actuator

SW601

Pickup

Controller

Board

Paper

Pickup Block

and pin, which press the
microswitch on the pickup
controller board. See
“Troubleshooting Tips” in
Troubleshooting for
information on defeating the
top cover interlock switch.

Basics Sensing System Theory - 29

Cassette
(None)
Legal
Letter
A4
Executive
B5

SW603 SW604 SW605

OFF OFF OFF

ON ON

ON ON
OFF
OFF
OFF OFF

OFF
OFF

ON ON
ON

OFF

ON

Paper

Pickup Block

Pickup

Controller

Board

SW603
SW604
SW605

SW603/4/5

Cassette Size Sensing
Switches (Upper)

Actuator: Plastic tabs on the
side of the cassette trays
actuate leaf springs, which
press microswitches on the
pickup controller board.
The tab/switch config­urations are as shown.

Note:

See the next page for a
note regarding the 250­sheet universal cassette.

Basics Sensing System Theory - 30

SW851/2/3

Cassette Size Sensing
Switches (Lower)

Actuator: Plastic tabs on the
side of a cassette tray
actuate leaf springs, which

Sheet Feeder

Controller Board

SW851
SW852
SW853

press microswitches on the
sheet feeder controller
board.

Note:

The sheet feeder uses
a 500-sheet universal
cassette. As with the upper
250-sheet universal
cassette, the tabs are set
manually by adjusting a
selection dial on the cassette.

Basics Sensing System Theory - 31

When you are troubleshooting, be aware that human error
can be a factor in paper-size sensing for these universal
cassettes.

Basics Test/Configuration Pages - 32

Test/Configuration Pages

There are three special pages that an operational
LaserWriter 16/600 PS can print. Each indicates
information that can isolate problems and/or identify the
configuration of the printer.

Startup Test Page

The printer generates a startup test page 2-3 minutes after
you switch on the printer. Successful printing of this page
indicates that the I/O board is operational.

Note:

The startup test page may not print due to

software disabling (see “Printer Utilities” in Basics).

Basics Test/Configuration Pages - 33

Service Test Page

The printer generates a service test page when you press the
service test page button. Successful printing of this page
indicates that the printer engine is operational.

Configuration Page

The printer generates a configuration page when you issue
the “Print Configuration Page” command with the printer
utility.

Note:

The “Print Configuration Page” command in the

Apple Printer Utility is located in the File menu.

Basics Test/Configuration Pages - 34

Ê

Startup Test Page

Printer Names

Communication parameters and
printer control language selected
for an individual printer port

ROM
version

Installed RAM

Printer Resolution

Number of pages
the I/O board has
produced

Other startup icons

FinePrint enabled

PhotoGrade enabled

Hard drive on-line

Optional feeders
installed

Basics Test/Configuration Pages - 35

Service Test Page

To access the service test
page button, open the
multipurpose tray. The
button is located in the
upper right corner of the
opening. The button is small
and difficult to see against
the black plastic. Use a
paper clip or similar tool to
press the button.

Basics Test/Configuration Pages - 36

The service test page pattern
is a series of vertical lines
that cover the imageable
area of the page.

Basics Test/Configuration Pages - 37

Configuration Page

This page provides the
following information to the
service technician.

• Network address settings

(1)

• Amount and allocation of

RAM memory and readout
of EEPROM integrity (2)

• Switch configurations

(3)

• HP LaserJet® emulator

version (4)

• Startup page setting (on

or off) (5)

• LaserWriter serial

number (6)

Basics Test/Configuration Pages - 38

• Halftone screen settings (7)

• System administrator password (8)

• Timeout settings (9)

• SCSI ID of printer and attached drives (10)

• Default paper tray and margin offsets (11)

If possible, always print a configuration page before calling
Apple Technical Assistance Center.

Basics Configuration Switch - 39

Configuration Switch

Configuration

Switch

Communication
Ports

The configuration switch is
located at the top of the I/O
controller board end
bracket. Configuration
refers to the communication
protocols that you assign to
each of the three ports.

When you set communication
protocols on older
LaserWriter printers, you
typically set a configuration
switch that has numerical
settings similar to a SCSI ID
switch. The number you

Basics Configuration Switch - 40

choose corresponds to one of ten codes in a predefined
configuration matrix.

With the LaserWriter 16/600 PS, the configuration switch
is a toggle between standard (down) and custom (up) values.
You define custom settings through software (see “Printer
Utilities” in Basics). This scheme allows users greater
flexibility in establishing configuration.

Basics LaserWriter Safety - 41

LaserWriter Safety

Unplug Printer

LaserWriter printers operate at high voltages. To prevent
serious injury, always switch off the printer and unplug the
AC power cord before servicing the printer.

Laser Beam Safety

Never disconnect the beam-detect cabling or laser shutter
when the printer is switched on. Also be careful not to place
screwdrivers or other shiny objects in the path of the laser
beam. The reflected laser beam, though invisible, can
permanently damage your eyes.

Never remove the cover of a laser/scanner assembly,
whether the printer is powered on or not.

Basics LaserWriter Safety - 42

Fuser Heat

The fuser assembly rollers become very hot during printer
operation. Before servicing the fuser assembly, switch off
the printer for at least 5 minutes to allow the fuser
assembly roller to cool.

Toner Safety

Toner is a nontoxic substance composed of plastic, iron, and
a small amount of pigment. Clean skin and clothing by
removing as much toner as possible with a dry tissue, then
washing with cold water. Hot water causes toner to jell and
permanently fuse into clothing. Toner attacks vinyl
materials, so avoid contact with vinyl.

Weight

LaserWriter printers are heavy. When lifting or moving
the printer, be careful not to strain your back.

K

Service Source

Specifications

LaserWriter 16/600 PS

Specifications Engine - 1

Engine

Engine

Printing Method

Optical System

Resolution

Canon LBP-P430 engine

Electrophotography using single-component microfine toner

Semiconductor laser and a rotating six-faced prism scanning

mirror

600 dpi

Specifications Engine - 2

Dimensions

Clearance Required

Weight

Operating
Environment

Height: 12.08 in. (307 mm)
Width: 16.73 in. (425 mm)
Depth: 16.89 in. (429 mm)

50.4” x 24.25” x 19.75” high (1282 x 616 x 501 mm)

Printer with cassette: 42.02 lb. (19.1 kg):
Toner cartridge: 3.3 lb. (1.5 kg)

Temperature: 50-90.5° F (10-32.5° C)
Humidity: 20-80% relative humidity
Atmospheric Pressure: 570-760 mmHg

Specifications Engine - 3

Power Consumption

Noise Level

Printing Speed

Duty Cycle

Approximately 0.79 kW at 71° F (20° C)

Sound Power Level:
66 dB or less (printing)
47 dB or less (standby)
Sound Pressure Level (Bystander Position)
52 dB or less (printing)
34 dB or less (standby)

17.1 pages per minute (letter)

16.2 pages per minute (A4)

No limit in pages per month

Specifications Engine - 4

Consumables
Service Life

Macintosh
Requirement

Pickup Rollers: 200,000 pages
Separation Pad: 200,000 pages
Fuser Assembly: 200,000 pages
Transfer Roller: 200,000 pages
Power Supply Fan: 25,000 hours
Controller Board Fan 25,000 hours
Front Fan 10,000 hours
Replace the multipurpose pickup roller and separation pad

together. The separation pad is contained in the multipurpose
tray guide assembly.

System Software 7.0 or later

Specifications Engine - 5

Printable Area (in
inches)

US Letter: 8.11 by 10.79
US Legal: 8.11 by 13.79
A4: 7.89 by 11.44
B5: 6.72 by 9.81

Specifications I/O Board - 6

I/O Board

CPU

RAM

ROM

AMD 29030 (RISC) running at 25 MHz

8 MB, expandable to 32 MB.
Refer to “Upgrading RAM” in Upgrades for more information.

4 MB standard
ROM may be either soldered or in the form of SIMMs. If you are

returning an I/O controller board to Apple that uses ROM
SIMMs, those SIMMs must accompany the board. Replacement
I/O controller boards that do not have soldered ROM will have
separately-bagged ROM SIMMs that you will need to install
onto the board.

Specifications I/O Board - 7

Pinouts

Settings

Imaging Languages
Supported

LocalTalk, Ethernet, and parallel connections

The LaserWriter 16/600 PS features automatic traffic control.

The printer can accept jobs simultaneously from AppleTalk,
TCP/IP, and NetWare networks and from the parallel port,
automatically switching between PostScript and PCL5
languages. No manual intervention is required if the standard
communication settings are adequate. See “Configuration
Switch” in Basics for information about customizing these
settings.

QuickDraw, PostScript Level 2 (2014), and HP PCL 5

Specifications Fax Card - 8

Fax Card

Features

When equipped with the fax card, the LaserWriter 16/600 PS

• Sends documents to any Group III-compatible fax machine or
printer from an Apple Macintosh or IBM PC compatible
computer.

• Receives and prints faxes at 200dpi from Group III-compatible
fax machines.

• Receives and prints faxes at 600dpi from other printers
equipped with PostScript fax capability.

• Send PostScript-language files to other printers that have
PostScript fax capability so that documents print at the
resolution of the receiving printer.

• Sends and receives documents at speeds up to 9600 bps.

Note:

There are two fax cards available from Apple, one for use

in the United States and one for international use. The USA fax

Specifications Fax Card - 9

card has built-in modem capability and can be connected
directly to an analog phone line. The international fax card is
designed to connect into an external modem.

Specifications Sheet Feeder - 10

Sheet Feeder

Dimensions

Weight

Power Consumption

Height: 5.28 in. (134 mm)
Width: 16.38 in. (416 mm)
Depth: 18.15 in. (461 mm)

13.2 lb. (6.0 kg) with cassette

24 VDC supplied by printer

Specifications Envelope Feeder - 11

Envelope Feeder

Dimensions

Weight

Power Consumption

Height: 5.03 in. (127.8 mm)
Width: 12.04 in. (306.5 mm)
Depth: 11.53 in. (293 mm)

5.72 lb. (2.6 kg)

24 VDC supplied by printer

Specifications Paper - 12

Paper

Input Sources and
Capacities

Output Source

Paper Sizes

Standard cassette (250)
Multipurpose tray (100)
Lower cassette (500)
Envelope feeder (75)

Face-down delivery tray

Standard Cassette:
A4, B5, legal, letter, or executive plain paper (16-24 lb.)
Cassettes available: letter, A4, or universal

Multipurpose Tray
Plain paper from 7.16 in. by 10.1 in. to 8.5 in. by 14 in. (16-

32 lb.), envelopes, and fuser-compatible labels and film

Specifications Paper - 13

Lower Cassette
A4, B5, legal, letter, or executive plain paper (16-24 lb.)
Cassette available: universal

Envelope Feeder
COM-10, DC, Monarch, C5, B5 (recommended envelope); from

3.54 in. by 7.44 in. to 7.0 in. by 10.0 in.

Note:

Do not use envelopes with clasps, snaps, windows, or
synthetic materials. Envelopes with peel-off adhesive strips
or double sealable flaps must use fuser-compatible adhesive.

K

Service Source

Troubleshooting

LaserWriter 16/600 PS

Troubleshooting General - 1

General

Troubleshooting contains quick-reference troubleshooting
information for the LaserWriter 16/600 PS. We encourage you
to review and print out this chapter before troubleshooting a
printer.

At the end of this chapter are troubleshooting flowcharts and
tables. If a table name clearly addresses your problem, you can go
directly to that table. If not, you should go to the flowchart
associated with the version of the printer you are working on.

Troubleshooting Power–On Self Test (POST) - 2

Power–On Self Test (POST)

When you switch on power, the LEDs are designed to illuminate in
a specific sequence as the printer comes ready. In a functioning
printer, all LEDs briefly illuminate about a second after you turn
on the printer to confirm power distribution . They then
extinguish and pulse as the fans power up and main motor rotation
takes place. About 5-6 seconds into printer startup, all LEDs will
again illuminate for one second. This marks the beginning of the
Power-On Self Test (POST).

POST is a diagnostic procedure built into the I/O controller board
that tests four areas: the SIMM/CPU, the I/O controller, the
engine, and a fax or hard drive, if present. As each checks passes,
the leftmost LED extinguishes. When all four checks have passed,
all LEDs remain extinguished for one second. The ready LED will
then flash once. The Power-On Self Test then ends, and control
passes over to the PostScript interpreter.

Troubleshooting Power–On Self Test (POST) - 3

Note:

The LED array that POST uses has no correlation to jam,
low-toner, or paper-out conditions. POST simply uses those LEDs
to relay coded feedback. Once control passes over to the PostScript
interpreter, the engine sensing system engages and LEDs do
correlate to their labels.

When POST does detect an error, it exits the LED-extinguishing
sequence and alternately flashes the toner and jam LEDs until you
turn off the printer. Observing which LEDs had extinguished
prior to the error array can help isolate the fault to one of the
four areas indicated.

POST Pass POST Fail LED Arrays

This movie shows where

POST occurs during startup.

This movie shows an example

of a detected engine problem.

This image shows the

normal meanings of LEDs.

Troubleshooting Printer Diagnostic (EPOST) - 4

Printer Diagnostic (EPOST)

Whereas the Power-On Self Test (POST) occurs during every
printer startup, the Extended Power-On Self Test (EPOST) occurs
only with intervention of the service technician. EPOST is a
diagnostic built into the I/O controller board that is designed to
run when the printer is in a modified state of operation.

To enable EPOST, turn off the printer, install a serial loopback
connector into the I/O controller serial port, and set the
configuration switch to the “up” position. Turn the printer on.

EPOST startup behavior is identical to POST up to the point where
an error is detected. In POST, startup is terminated and a general
error display is reported to the LED panel. In EPOST, error
reportingis extended. Consequently, about a dozen, more specific,
error codes are able to be displayed. See next page for a chart of
failure error codes.

Troubleshooting Printer Diagnostic (EPOST) - 5

If EPOST detects an error, the LEDs will cycle through the
following sequence until you turn off the printer. The QuickTime
movie below animates this cycle.

• All LEDs on for one second

• All LEDs off for one second

• Failure error code for two seconds

• All LEDs off for one second

Caution:

diagnostic, be sure to remove the serial loopback cable and set the
configuration switch in its original position. Any readout other
than those shown above is an unknown error that cannot be
detailed any more specifically.

When you have finished running the Extended POST

Troubleshooting Printer Diagnostic (EPOST) - 6

Ê

I/O Controller Board

ROM SIMM A

RAM Size

RAM SIMM (Low)

RAM SIMM (High)

Engine Controller (Interface or NVRAM)

Fuser Assembly

Laser/Scanner Assembly

Misc. Engine (Operator or Unknown Error)

Engine Fan (1 or More)

Main Motor

SCSI Hard Drive (Present but Failing)

Troubleshooting Printer Diagnostic (EPOST) - 7

The LaserWriter 16/600 PS requires the mini DIN-8 serial
loopback connector that is listed as part of one of the diagnostics
kits available from Apple. This connector can also be ordered
separately as part number 922-1489.

Serial Loopback Connector

Troubleshooting Printer Diagnostic (EPOST) - 8

For those service providers who would like to build their own
loopback connector, the plug consists of a male mini DIN-8
connector with pins 1 and 2 tied together using a piece of small­gauge wire-wrap wire. The pins on the male end of the mini DIN­8 connector are numbered as shown:

678

34 5

12

Troubleshooting Maintaining I/O Connectivity - 9

Maintaining I/O Connectivity

If you want to troubleshoot the printer while maintaining
connectivity to a host computer, you must temporarily reposition
the printer’s I/O controller board. In this reconfigured state, you
will be able to print from a paper source other than the standard
cassette, observe the behavior of LEDs during startup, or run the
printer diagnostic, while still having the engine open for
troubleshooting.

To reconfigure the I/O controller in this way, remove the rear
panel, I/O controller board, and I/O shield. Remove the printer
interface cable from the I/O controller board and temporarily
substitute a Quadra 900/950 floppy drive 20-pin cable.
Connect the free end of this long interface cable to connector J207
on the DC controller board. Reconnect the power cable to
connector J15.

Troubleshooting Maintaining I/O Connectivity - 10

Ê

Maintaining
I/O Connectivity

I/O Board

Quadra 900/950 Floppy Drive Cable

J207

Troubleshooting Troubleshooting Tips - 11

Troubleshooting Tips

Multimeter Probes

The connectors within the LaserWriter 16/600 PS are very
small and require sharp needle-point probes to make good contact.
Do not use probes that do not make proper contact. To see whether
a set of probes works properly, test resistance at connector J210
on the DC controller board in the manner described below (the
cable must connected to the board).

Set your multimeter to resistance and insert the probes at pins 1
and 10. If the reading indicates continuity then the probes are
making good contact. If the reading indicates infinite resistance,
then the probes do not make contact and should not be used with
this printer.

Troubleshooting Troubleshooting Tips - 12

Forcing a Feed Cycle

If you want to print from anything other than the standard 250­sheet cassette tray, you must be connected to a CPU and select the
feed option that you want. It is not possible to print a service test
page from any source other than the standard cassette.

Troubleshooting Troubleshooting Tips - 13

Interrupting a Print Cycle

Interrupting a print cycle and inspecting the photosensitive drum
can help isolate the cause of print quality problems. If the image
on the surface of the drum exhibits the same problem as the
printed page, the fault is before the drum, probably in the
imaging system.

If the image on the drum is OK, the fault is after the drum,
probably in the fuser assembly, transfer block, or high-voltage
power supply. To inspect the drum in this way, run a print and
wait until the paper clears the synchronization pause at the
registration paper sensor. Open the toner access door, remove the
toner cartridge, and pull back the shield to inspect the drum.

Troubleshooting Troubleshooting Tips - 14

Maintaining Pickup Connectivity

To troubleshoot the paper pickup block, you must temporarily
reconfigure the printer’s paper path so that the pickup block is
exposed. In this reconfigured state, you will be able to take
voltage readings from the pickup controller board and observe
paper feeding from the cassette.

Note:

Since paper will jam due to the disruption of the paper
path, you must disable the startup test page (see “Printer
Utilities” in Basics) before turning the printer back on. Make
sure to enable the startup test page before returning the printer
to the customer.

To reconfigure the paper path, remove the pickup block, set it at
an angle to the printer, and reconnect cables J601 and J603 at the
leading edge of the pickup controller board. Insert the cassette
tray into the pickup block. Press down the top cover interlock
actuator and force the interlock switch closed by wedging in the

Troubleshooting Troubleshooting Tips - 15

hooked end of the green cleaning brush. Reinstall the top cover and
cover liner and close the lid.

If you want to test pickup from the multipurpose tray or the
envelope feeder, you must maintain I/O connectivity (see
previous topic). You cannot run a service test page from any
source other than the standard 250-sheet cassette.

Caution:

the metal chassis when performing this procedure.

Do not let the pickup controller board brush up against

Troubleshooting Troubleshooting Tips - 16

Defeating the Top Cover Interlock

You may occasionally need to defeat the top cover interlock to
simulate a “top cover shut” condition. To defeat this sensor, open
the toner access cover and wedge a stiff, non-metallic insert into
the interlock switch opening. Push the insert down to depress the
interlock leaf spring.

Troubleshooting Troubleshooting Tips - 17

Defeating the Fuser Door Interlock

You may occasionally need to defeat the fuser door interlock to
simulate a “fuser door shut” condition (for example if you wanted
to observe paper as it exits the fuser rollers). To defeat this
sensor, open the fuser access door and wedge the brush end of the
green cleaning brush into the delivery/interlock sensor.

Green Cleaning Brush

Troubleshooting Troubleshooting Tips - 18

Caution:

removing the brush, make sure that the delivery sensing arm
moves freely and is not snagged.

Do not insert the brush too far into the sensor. After

Troubleshooting Troubleshooting Tips - 19

Sheet Feeder Bypass

You can visually troubleshoot a functioning stand-alone sheet
feeder by bypassing connector J603 on the printer’s pickup
controller board.

Disable the startup test page, and remove the top cover, rear
panel, and right corner panel from the printer. Disconnect J603
from the exposed edge of the pickup controller board and connect a
spare sheet feeder interface cable (P/N 922-0219). Plug the
opposite end of the interface cable into the sheet feeder receptacle.

Troubleshooting Troubleshooting Tips - 20

Observing Envelope Feed

You can visually inspect and/or take multimeter readings from a
fully functioning envelope feeder. Remove the covers of the feeder
and install it into the printer. The feeder will operate in normal
fashion.

Envelope Feeder
(without covers)

Troubleshooting Troubleshooting Tips - 21

Drum Exposure

Cover the toner cartridge when you remove it from the printer.
Prolonged exposure to light can result in print quality problems.

If this has occurred, store the toner cartridge in a dark place. The
drum will return to its normal condition after about 24 hours.

Troubleshooting Capacitor Discharge - 22

Capacitor Discharge

When there is a failure of the fusing system, the DC controller
board shuts off current to the fuser roller heater and charges
capacitor C208 to prevent overheating. If there is a failure of the
fusing system, you must turn the power off for about 10 minutes
or manually discharge the capacitor before switching power back
on.

C208

DC Controller Board

Troubleshooting Capacitor Discharge - 23

Caution:

before performing this procedure.

To discharge capacitor C208, switch off the printer and remove
the rear panel, I/O controller board, and I/O shield. Carefully
jumper the two wires at the base of the capacitor using some kind
of conductor.

Note:

the capacitor: a flat blade screwdriver, paper clip, or aluminum
foil doubled over. The tool illustrated is a length of lead solder. It
has the advantage of being ductile and is less apt to damage the
controller board.

Be sure to switch off power and unplug the printer

There are many different tools that can be used to discharge

Troubleshooting Capacitor Discharge - 24

Discharging
Capacitor C208

C208

Troubleshooting Expansion Post Connectors - 25

Expansion Post Connectors

The LaserWriter 16/600 PS has several cable receptacles that
are secured to the printer by finned post connectors. The fins
expand when you insert the connector, but once the connector is
installed it can be difficult to remove.

If you cannot remove these connectors with your fingers, try
small bent-nose pliers, a 5 mm nut driver, or grip-rings forced
around the post.

Caution:

upside-down, they will not couple properly.

The cable receptacles are keyed. If you install them

Troubleshooting Expansion Post Connectors - 26

Fin

Cross Section

Fin

Expansion Post Connector

Troubleshooting Toner Cartridge Modification - 27

Toner Cartridge Modification

LaserWriter toner cartridge part number M2473G/A is the only
cartridge from Apple specifically designed for the LaserWriter
16/600 PS.

However, you may also use Revision B LaserWriter Pro 600/630
toner cartridges in the LaserWriter 16/600 PS. The Revision B
cartridges were introduced in late 1993 and were designed to be
forward-compatible.

Warning:

LaserWriter Pro 600/630 toner cartridge in the LaserWriter
16/600 PS. You can distinguish the new revision B toner
cartridge by the 1” x 3.5” molded ridge on the top surface. If this
ridge is not present, do not use the toner cartridge with the
LaserWriter 16/600 PS.

You must not use the original version of the

Troubleshooting Toner Cartridge Modification - 28

Toner Cartridge
Modification

Troubleshooting Circuit Board Diagrams - 29

Circuit Board Diagrams

On the following pages are diagrams of the circuit boards and
high-voltage contacts listed below:

• I/O Controller Board

• Fax Card (Domestic)

• Fax Card (International)

• DC Controller Board

• Pickup Controller Board

• Pickup Sensor Board

• High-Voltage Power Supply

• Envelope Feeder Controller Board

• Sheet Feeder Controller Board

Troubleshooting Circuit Board Diagrams - 30

ROM SIMM Slots (empty if soldered ROM)

RAM SIMMs

(To Engine)

J1

IOP ROM

BA DC

Soldered ROM (not
present on all boards)

J23

(To Power)

J21 Connector for Internal Hard Drive
(see “Addiing Hard Drives” in Upgradess)

I/O Controller Board

Configuration Switch

Centronics Parallel

J15 Fax

Opening for Fax Port

Ethernet

LocalTalk

SCSI

Troubleshooting Circuit Board Diagrams - 31

Solder Side Component Side

Fax Card

(Domestic)

J2
(Fax Card)
mates into

J15

(I/O Board)

Ghosted image is outline of I/O controller board.

Fax Card (Domestic)

Speaker

Battery

Fuse

Modem

IC

J2

Troubleshooting Circuit Board Diagrams - 32

Solder Side Component Side

Fax Card

(International)

J3
(Fax Card)
mates into

J15

(I/O Board)

Ghosted image is outline of I/O controller board.

Fax Card (International)

Battery

J3

Troubleshooting Circuit Board Diagrams - 33

C208

J201

J203 J206

J204 J205

J211

J212J214

VR201 (see “Registration
Adjustment” in Adjustments.)

J207

J208

J213

J209

J210

TB201

DC Controller Board

Troubleshooting Circuit Board Diagrams - 34

Service Test
Page Button

Cover Interlock

J604

J605

Cassette Size

Microswitches

SW601

Switch

SW602

SW603
SW604
SW605

J601

J603

J602

Pickup Controller Board

J604

J605

Troubleshooting Circuit Board Diagrams - 35

J704
J703
J702

PS702

Multipurpose Tray

Paper-Present

Sensor

PS701

Multipurpose Tray

Paper-End

Sensor

Pickup Sensor Board

Pickup Controller

Board Receptacle

J701

Troubleshooting Circuit Board Diagrams - 36

J402

VR401

TB406

TB405

TB403TB404

High-Voltage Power Supply

PS Interface Board

Receptacle

J401

TB402 TB401

Troubleshooting Circuit Board Diagrams - 37

Envelope Feeder
Controller Board

J931

PS931

J932

Troubleshooting Circuit Board Diagrams - 38

Sheet Feeder
Controller Board

J853 J851

PS851 J852

SW851
SW852
SW853

Tab Cutout

Cassette Size
Microswitches

Troubleshooting Wiring Diagram - 39

Wiring Diagram

The LaserWriter 16/600 PS wiring diagram can be found on the
next page. The detail in this document is too small to read easily at
100% view. You should either zoom into the diagram using the
zoom tool above, or print the diagram on a laser printer with a
resolution of 300 dpi (600 dpi preferred).

TP1

H1

PRI

DEV

ANTIN

TONER

CARTRIDGE

67

3

FUSER ASSEMBLY

TH1

J744

LOW

UP

F

GND

2

TB406
TB402

TR

TB401
TB405
TB403

GND

TB404

TRANSFER

BLOCK

34
12

J136

8
1

J743

123

PICKUP CONTROLLER BOARD

J402

ANT

D742
D741

J401

GND

8
7
6
5
4
3
2
1

B5
A5
B4
A4
B3
A3
B2
A2
B1
A1

HV

REF

POWER
SUPPLY

13

J601

1
4

J603

1

J602

B
A

5

(Solder Side)

HIGH-VOLTAGE

CONNECTOR BOARD

8
7
6
5
4
3
2
1

J743
J742

B5
A5
B4
A4
B3
A3
B2
A2
B1
A1

LED

STATUS

PANEL

1

J604

4
1

1

J605

6

Main Power

J741

10

9
8
7
6
5
4
3
2
1

GND

GND

6

DISP4

5

DISP3

4

DISP2

3

DISP1

2
1

+5V

HVRST
/TVOUT
SLI2

SL02

1
2

3

4
5
6

M1

GNDTH

FSRTH
+24VB
+5V

TVIN

J204

J211

GND

+24VD

1234

J131

J210

1234

/MON

/MRDY

5

/TXD

+24VD

J203

12345678910

+5V

/RXD

SW101

12

J102

POWER SUPPLY

J104

123

RLD

/FSRD

THOUT

123

J212

12345678910111213

1234

GND

GND

SLO1

MAIN MOTOR

Switch

123456

+5V

123456

PAP

PBP

SLI1

LINE

INPUT

1

J101

2
3

J105

4

J103

+5V

GND

GND

GND

+24VA

TB201

DC CONTROLLER BOARD

J201

+5V

GND

GND

+24VA

+24VA

+24VB

+24VB

DOPEN

PDS

1
2

J15

3
4

1234567891011121314151617181920

/BD

GND

1234567891011121314151617181920

1234567 123456 1234

LASERWRITER

16/600 PS I/O BOARD

/STS

/RDY

/PCLK

/SBSY

/VSREQ

APCIN

/VDATA

/LON

/ENBL

/CBSY

/PPRDY

GND

APCOUT

LASER DRIVER

J2

/PRNT

J207

+5V

GND

/CMD

/VSYNC

/CPRDY

/SCNRDY

/SCNON

+24VA

SCANNER

MOTOR UNIT

GND

/CCLK

J205J206

GND

SCNCLK

M5

/VDO

GND

J13

GND

1

40

GND

123

J209

'H' When

Tripped

123456781234567

+5V

/BDI

GND

J731J151J721

BEAM DETECT

IC UNIT

FM1

FAND

J214

J213

J208

GND

FLOCK

EXHAUST

FAN

1
2
3

1
2
3

4

1
2
3

DELIVERY/

INTERLOCK

EXHAUST

FANS

FAND

FLOCK

GND

FAND

FLOCK

GND

123

PS201

SENSOR

PSNS

GND

FM2

FM3

PSL

LASER/SCANNER ASSEMBLY

SL851

Pickup Roller

Clutch Solenoid

M3

A
/A
B
/B

SW852

SW853

SW851

Cassette Size

Sensing Switches

J853

1
2

PS851

3
1

2

Sheet Feeder

3

Paper-Present

4

Sensor

J852

J851

+24VA

2NDO

2NDI
GND

1
2
3
4

F

F

SHEET

FEEDER

(Optional)

J135

ENVELOPE

FEEDER

(Optional)

1
2

J603

3

J604

4

1234

EBVI

EBVO

+24VA

J136

J931

1234

PS931

Envelope Feeder

Paper-Present Sensor

GND

F
F

J932

4

1
2
3

1 2 3 4 5 6 7 8 9 10 1112 13

J601

A
/A

M4

B

/B

PAPER SENSOR

'H' When Door

Is Open

J605

123456

GND

1STL

1STS

'L' When
Tripped

123 123

PS601 PS602

CASSETTE

PICKUP CONTROLLER BOARD

SW601

'L' When Tripped

SENSOR HOLDER

ASSEMBLY

GND

RESL

RESS

REGISTRATION

PAPER SENSOR

'H' When Tripped
'L' When Tripped

J602

A1 B1A2 B2 A3 B3 A4 B4 A5 B5

A1 B1A2 B2 A3 B3 A4 B4 A5 B5

PA

/PAMP/PB

PS701

Multipurpose

Paper-End

Sensor

PB

1ST

MPS

PS702

Multipurpose

Paper-Present

Sensor

MPE

GND

PICKUP SENSOR BOARD

SW602

Service Test
Page Switch

J701

J702

+24VA

J703

J704

Sensing Switches

+24VA

1

MPD

2

GND

3

PA

1

/PA

2

PB

3

/PB

4

+24VA

1

1STD

2

Cassette Pickup Roller

SW603/4/5

Cassette Size

Multipurpose

Pickup Roller

Clutch Solenoid

SL702

SL701

Clutch Solenoid

M2

Troubleshooting Connector J136 Locator - 41

Connector J136 Locator

J136 is the connector that the envelope feeder mates into. To see
it, open the multipurpose tray and remove the closure panel. The
illustration below shows the connector as it appears from the
outside of the printer.

A voltage reading of 24V between pins 1 (+24VA) and 4 (GND)
during printer startup indicates that motor power is reaching the
envelope feeder.

34

12