Apple LaserWriter Select Troubleshooting Guide

Apple's diagram of the Select 300/310 DC controller board. Most of the meter checks below are made on its connectors; P32 at the lower left prints the service test page.

Fault-finding for the LaserWriter Select printers (Apple LaserWriter Select 300, Apple LaserWriter Select 310 and Apple LaserWriter Select 360), taken from Apple's LaserWriter Select Service Source. Apple's method is module replacement guided by connector-pin measurements: each of its 30 troubleshooting tables ends in "replace the power supply", "replace the DC controller board" or a similar module, and the manual gives no schematic and no component values. Read the safety rules and the live-test set-up on Apple LaserWriter Select General Maintenance before taking any of the readings below: several are made with the covers off and the printer switched on, close to the mains-fed fuser and the high-voltage supply.

Before you start

Apple's procedure for every table is to retry the printer each time you change its physical state, and to put the original module back if a replacement does not cure the fault before moving to the next step.

• Use sharp needle-point probes. The connectors are small, and a probe that does not seat gives a false reading.
• Most readings are taken against P11-2 (black wire) on the DC controller board, the ground pin of the power supply connector.
• A Select 360 must not run for more than 10 minutes with its covers off, and its main motor stops whenever the paper cassette is out.

Engine or I/O board?

The first split is between the print engine and everything upstream of it.

The service test page is a line matrix printed by the DC controller board alone. Jumper the two pins of P32 on the DC controller board, either with a paper clip through the access hole in the back of the I/O controller mount or directly with the mount removed and a folded paper in the delivery sensor PS201. If the test page is good and the fault only appears when printing from the computer, the engine is working and the fault is in the I/O controller board, cable, driver or host. If the test page shows the fault, work through the engine tables below.

On the 310 and 360 the power-on self test narrows a dead printer down further. All three LEDs light at switch-on and go out in order: Ready when the I/O controller board passes, Paper-Out when the RAM passes, Paper-Jam when the engine passes. The LED left lit marks the failed stage. The Select 300 has no self test; its errors are shown on the Macintosh screen, so disable background printing to see them. The Select 360 also has a diagnostic LED mode, entered with the JMP1 jumper removed and the rear mode switch at 9, which names the failed module; the patterns are listed on Apple LaserWriter Select 360#Self test and diagnostic LEDs.

Power, motor, fuser and laser

Engine faults (Apple's Tables 1-5 and 9-12)

Symptom	Apple's table	Checks, in Apple's order
Main motor does not turn	Table 1	P14 seated on the DC controller board; obstructions or damaged gears in the drive assembly, paper feed roller or cassette feeder; about +24 V DC at P14-1 (A-COM) and P14-2 (B-COM) to P11-2 at switch-on; motor coils about 5 Ω from P14-1 to P14-3 and P14-5, and from P14-2 to P14-4 and P14-6. Coils good: replace the DC controller board, then the motor. Coils open: replace the motor.
Fan does not run	Table 2	Toner cartridge fitted; outlet voltage; P119 on the paper delivery sensor; the fuser assembly lever covering PS201 when no paper is present; supply voltages at P11 (below); about +24 V DC from P18-3 to P18-2 (RTN) with the fan cable on (present: replace the fan); +5 V DC from P119-3 to P119-2 with P119 unplugged from the sensor.
Fuser does not heat	Table 3	Cartridge fitted; 90-132 V AC at J101-2 to J101-6 on the fuser assembly at switch-on (absent: power supply); thermistor 200-350 kΩ between P11-13 (STS) and P11-14 with P11 unplugged; heater bulb and thermoprotector under 10 Ω across J101-2 and J101-6 (higher: replace both); P11-1 (HEAT) about +4.2 V DC at switch-on, and about +3.7 V with the front door open, dropping briefly to 0 V about five seconds after closing it; 5 VB at P11-5 with P111 unplugged from the high-voltage supply; whether the heater bulb lights with P12 unplugged (no: laser/optic assembly) or with P15 unplugged (yes: DC controller board); toner cartridge sensor switches (Table 10).
Laser or scanner failure	Table 4	P12 and P19 seated; scanner motor heard to spin after the main motor stops; about +5 V DC from P11-5 (5 VB) to P11-4; under 5 Ω from P11-5 to P12-7; +5 V DC from P12-7 to P12-6 at switch-on (present: replace the laser/optic assembly; absent: DC controller board).
Scanner motor does not run	Table 5	About +24 V DC from P12-13 to P12-12 (RTN); /MOT ON at P12-11 below 1 V while printing and about +4 V when printing stops (correct: replace the scanner assembly, then the laser and scanner motor cable; wrong: DC controller board).
Temperature sensor	Table 9	Fuser removed and cold: 200-350 kΩ from J101-1 to J101-4 on the fuser assembly. Otherwise replace the sensor assembly.
Toner cartridge not detected	Table 10	+5 V DC from P15-8 (5 VB) to P11-2; P15-8 to P15-9 and P15-10 (EP CHECK) to P15-11 each 0 Ω with a cartridge in and open circuit with it out; the actuator closing switches S100 and S101 on the sensor board; continuity from P15 to P118.
+24 V missing	Table 11	+24 V DC from P11-12 (orange) to P11-2 (absent: power supply); P11-10 and P11-11 (brown) 0 V with the front door open and +24 V with it closed.
+5 V missing	Table 12	+5 V DC at P11-5 (yellow, 5 VB) and P11-6 (blue, 5 VA) to P11-2. Absent: power supply; present: DC controller board.

The power supply voltages at P11 on the DC controller board, measured to P11-2, are the reference for most tables:

Expected readings at P11, DC controller board

Pin	Wire	Expected
P11-10, P11-11	Brown	+24 V DC with the front door closed; 0 V with it open
P11-12	Orange	+24 V DC
P11-5 (5 VB)	Yellow	+5 V DC
P11-6 (5 VA)	Blue	+5 V DC
P11-1 (HEAT)	Red	About +4.2 V DC at switch-on
P11-13 to P11-14 (P11 unplugged, cold)		Thermistor, 200-350 kΩ

Paper handling

The four paper sensors are the paper delivery sensor PS201 (on the I/O controller mount, actuated by a lever on the fuser), the registration sensor PS602, the manual feed sensor PS701 and the paper-out sensor PS601.

Paper faults (Tables 13, 14 and 27-30)

Symptom	Apple's table	Checks
Paper-Out LED lit with paper loaded	Table 13	Cassette filled and seated; paper sensing arm; bent cassette size actuators (cassette feeder board); main motor turning when the cassette goes in; with P111 off the high-voltage supply, P13-1 (NOPAPER1) to P13-4 toggling between +5 V (tray out) and 0 V (tray in); P13-3 (NOPAPER2) for an optional cassette.
Paper-Jam LED lit with no jam	Table 14	Cassette; paper fragments in the fuser, delivery or registration area; the delivery sensor cable; the delivery lever on the fuser swinging freely during a test page; the paper sensing arm on the paper charge deflector; with P111 and P16 unplugged, +5 V from P16-4 (PULLUP) to P16-5; P16-6 falling from +5 V to 0 V as paper passes the registration sensor; P16-3 (EXIT) to P16-2 dropping to 0 V when paper is taken out of PS201; then the +5 V supplies at P11.
Jams in the fuser or delivery area	Table 27	Starts with a service test page to see whether it jams as it leaves the fuser.
Jams in the pickup area	Table 28	Includes the registration sensor signal falling from +5 V to 0 V as paper passes, and +24 V falling to 0 V when the manual feed pickup solenoid operates.
No pickup from the cassette	Table 29	Includes a signal that reads 0 V with a filled cassette inserted and +5 V with it removed.
No pickup from manual feed or the multipurpose tray	Table 30	Includes a signal falling from +5 V to 0 V when a sheet is placed on the manual feed tray.

Connection and driver faults

Tables 6 to 8 cover the I/O side. Check the cable; on a Macintosh, the Select driver (310) or the LaserWriter 8.0 driver (360) and the right port in the Chooser; with the printer on the Macintosh printer port, AppleTalk set inactive; and background printing switched off so that error messages reach the screen. Only then try a different I/O board. For a parallel connection, check the cable and that the host software is set for the parallel port.

Print quality

Apple's image-defect chart sends each defect to its own table. The first step in nearly all of them is a known-good toner cartridge.

Print quality (Tables 15-26)

Defect	Table	Further checks
All-blank page	15	Sealing tape still in the cartridge; high-voltage contacts touching the cartridge; anything blocking the laser outlet in the chassis or the beam slot on the cartridge; damaged drive gears; transfer roller; +24 V DC from P15-7 to P15-1; continuity of every contact on the high-voltage contact assembly; continuity from RTN (red wire) on the high-voltage supply to the spade on the paper delivery guide; DC controller board; then the toner sensor and high-voltage supply cable, then the high-voltage supply.
All-black page	16	High-voltage contacts; +24 V at P15-7; contact continuity.
Light or faded image	17	Known-good paper; contacts; +24 V at P15-7; high-voltage contact assembly.
Dark image	18	Dirty transfer roller (replace it); +24 V at P15-7; high-voltage contact assembly.
Black vertical lines	19	Transfer roller; the grounding contact to the static eliminator.
White vertical lines	20	Foreign material at the laser beam outlet or on the cartridge slot.
Black horizontal lines	21	High-voltage contacts; +24 V at P15-7.
White horizontal lines	22	Damp paper; cartridge; +24 V at P15-7; high-voltage contact assembly.
Ghosting	23	Dirty transfer roller (replace); scratched fuser heater or pressure roller; +24 V at P15-7; high-voltage contact assembly.
Bad fusing	24	Damp paper; fuser seated; then known-good fuser, power supply and DC controller board in turn.
Blank spots	25	Damp paper; dirty transfer roller; scratched fuser rollers.
Toner on the back of the page	26	Operating environment against Apple's checklist; transfer roller; fuser rollers.

Related pages

• Apple LaserWriter Select General Maintenance
• Apple LaserWriter Select 300, Apple LaserWriter Select 310, Apple LaserWriter Select 360
• LaserWriter Select Service Source
• Service Training Laserwriter Select Service Course Version 1.1 1996