Apple ImageWriter II Troubleshooting Guide

ImageWriter II (photo: Blake Patterson, CC BY 2.0)

Fault finding for the Apple ImageWriter II, from Apple's ImageWriter II Technical Procedures, with the voltage and component checks from Sams ComputerFacts CP27. For the original ImageWriter see Apple ImageWriter Troubleshooting Guide; for the ImageWriter LQ see Apple ImageWriter LQ Troubleshooting Guide.

Before you start

• If an option card is fitted, remove it and set DIP switch 2-4 to open (off) before troubleshooting.
• Work through the things-to-check list first, then run the self-test (hold form feed while pressing on/off). Run it before connecting the printer to a computer: where it stops shows which module to look at.
• In the symptom table, try the first action, then the next. If you replace a module and the fault remains, put the original back before moving on.
• The flowcharts use a digital multimeter on its 200 Ω range; a reading of 1 means open circuit and 0.00 means continuity. Do resistance checks with the printer switched off.

Things to check

Things to check (Technical Procedures, pp. 3.4-3.5)

Symptom	Check
Error light blinks	Carrier cover in place and its magnet present. A left margin error while printing may be a software problem: try other software. Option card switch (2-4) open/off with no card fitted.
Select light off, error light on	No paper, or paper wrongly loaded.
No printing or garbled printing	Interface cable loose or disconnected; DIP switches 2-1 to 2-4 set wrongly.
Problem with one program only	Try known-good software.
Prints correctly for a while, then garbage	Set switch 2-3 to the correct handshaking protocol.
Overprinting	The program's line spacing and line length settings.
Light printing	New ribbon cartridge; adjust the impression lever.
Erratic carrier movement and a loud hum	Remove the black tube-shaped shipping protection from the carrier shaft.
Squashed lines or misregistration on pin-feed paper	Paper stack behind the printer with a clear path; power cord and printer cable out of the paper path; manual paper sensor, paper guide or paper bail pressing too hard; tractors letting paper slip; print head gap (shims). Avoid printing in the top and bottom inch, and try 20 lb paper.

Symptom table

Symptom table (Technical Procedures, pp. 3.6-3.9)

Symptom	Actions, in Apple's order
Compressed first or second line	Replace the CPU PCB.
Print darker or lighter on one side	Check the shims (print head gap).
Top row of dots missing	Ribbon adjustment.
From a Macintosh, smudged characters, or top of form creeping down one line at a time	Install the current ImageWriter driver.
Power light on, no printing	Ribbon frame riding on the spiral ridge of the colour ribbon cam; pins in the dot head PCB connector not bent; then flowchart 2.
Missing dots	Flexible cable connected; dot head PCB connector pins not bent; then flowchart 5.
Carriage does not move, LEDs off	Drive PCB, transformer, filter assembly.
Carriage does not move, LEDs on	CPU PCB, drive PCB.
Carriage moves left and does not return to centre	Switch on the print head PCB (replace the head PCB if it is stuck), CPU PCB, print head PCB, flexible ribbon cable, drive PCB.
Carriage moves left and hums loudly	Flexible ribbon cable seated at the drive PCB and under the carriage; replace the flexible cable, then the print head PCB.
No carrier movement after take-apart (panel lights on), or carriage grinds or is hard to move	Remove the bottom cover and check that the carrier motor wires are not pinched or worn; replace the fuse on the drive PCB; replace the drive PCB.
Grinding during paper feed	Remove the platen knob and clear the gearing beneath it; adjust the paper guide; paper feed motor; drive PCB.
Paper-out sensor interferes with the paper path (left side tighter under the platen)	Bend the mechanical paper sensor slightly lower into the platen cradle.
Hexadecimal data printed	Switch off and on.
IC3 on the drive PCB visibly blown	Replace the line feed motor, drive PCB and CPU PCB together. Apple warns that replacing fewer than all three can blow further modules.
Power supply keeps failing	Check that the cut-sheet feeder wires are not pinched; lift the chassis and reposition them.

Flowchart checks

Apple's seven flowcharts cover power light not lit, power light on with no printing, no paper feed, ribbon colour selection, print quality, the option card and a final test. Their notes give these measurements.

Measurements in the flowchart notes (pp. 3.10-3.22)

Part	Where to measure	Expected
Fuses on the drive PCB (5 A and 1 A)	Remove and test each fuse. Remove the mechanical assembly before checking the fuse on the noise filter PCB.	Continuity (0.00)
Power switch	Plug-in connectors from the switch to the right support leg: white to white, black to black	Open (1) when off, continuity when on; white to black open in both positions
Form feed switch	Operation panel connector pins 12 and 13	Open; continuity when pressed
Line feed switch	Operation panel connector pins 11 and 13	Open; continuity when pressed
Home position switch (on the head PCB, under the left of the ribbon carrier)	Flexible cable pins 10 and 12, cable detached from the drive board	Continuity when pressed, open when released
Paper feed motor	Cable connector, pins 6-4, 6-2, 5-1 and 5-3 (pin 1 is the black wire)	About 22 Ω each
Paper feed motor	Pins 3-1 and 2-4	About 44 Ω each
Ribbon motor, through the flexible cable	Pins 3-7, 5-7, 4-8 and 6-8	About 120 Ω each
Ribbon motor, through the flexible cable	Pins 3-5 and 4-6	About 240 Ω; if not, the ribbon drives down but not up: replace the flexible cable
Print head	Head removed, PCB side down, edge connectors towards you: across the far-right finger	About 3 Ω

• If the carrier will not move by hand, check that the ribbon winds when its knob is turned in the direction of the arrow, look for damage or debris on the carrier shaft and belt, check the ribbon wire, and clean and oil the carrier shaft.
• With a logic board from February 1987 or later, check the paper sensor jumper: pins 1-2 for the mechanical sensor, 2-3 for the optical sensor.
• Option card: switch 2-4 must be closed (on) with a card fitted. With the memory option card, the printer tests the card's RAM at power-on; if the printer comes ready, the RAM is good. For the AppleTalk card Apple refers to its NodeCheck diagnostic.

Fuses

The drive PCB, under the bottom cover, carries two fuses: fuse 1 is 1 A and fuse 2 is 5 A. The noise filter board has a third. Sams' fuse list agrees: 2 A 250 V AC on the AC line filter board, and 1 A 125 V AC (FU1) and 5 A 125 V AC (FU2) on the power supply board. The short replacement-parts list on the Sams cover gives FU1 as 2 A 250 V fast-acting and FU2 as 5 A 125 V slow-blow, which does not match its own fuse list or Apple.

Sams' advice on a blown fuse:

• FU (line filter board): check coil L1 on the line filter board, the transformer T1 primary and secondary, and the bridge rectifier IR1 before fitting a new fuse.
• FU1: check the carriage motor M3 windings and the carriage motor driver IC (HIC1) for shorts to ground, and that the carriage moves freely.
• FU2: check for shorts at the bridge rectifier IR1, the regulator IC HIC2 (pins 6, 10 and 14) and the collector of switching transistor Q6.

Voltage and winding checks (Sams)

Sams ComputerFacts CP27 preliminary service checks

Check	Expected	If wrong
Transformer T1 primary, white lead to black lead	120 V AC	Power switch SW1, noise filter L1, mains cord
Connector CN4 pins 1 and 2 on the power supply/driver board	30 V AC	Transformer T1 and CN4
Regulator IC HIC2 pin 14	About 37.2 V	Transformer T1 and bridge rectifier IR1
Cathode of zener diode ZD2	About 25.0 V	CN2(A) and the power supply/driver board
CN2(A) pins 49 and 43	5.0 V	As above
CN2(A) pin 47	−5.0 V	As above
Print head windings	3 Ω each	Print head
Carriage motor (CN8: pin 5 to pins 1 and 3, pin 6 to pins 2 and 4)	3.5 Ω each winding	Carriage motor
Line feed motor (CN6)	22 Ω each winding	Line feed motor
Colour ribbon cam motor (CN5: pin 7 to pins 3 and 5, pin 8 to pins 4 and 6)	120 Ω each winding	Ribbon cam motor

Sams also describes the printer's built-in loopback test, run with a loopback plug in the interface socket, and how to trace a loopback failure on a printer whose self-test works.

ImageWriter II/L

The II/L has a switching power supply board instead of a transformer. It produces +5 V and −5 V for logic and +26 V for the motors, delivered from CN5 on the power supply board to CN3 on the main logic board. The power supply board has two fuses, FU1 (2 A) and FU2 (4 A, 125 V), and a further FU1 on the main logic board protects the +26 V motor supply. Its own symptom charts and flowcharts are in the II/L Technical Procedures in the same volume.

Related pages

• Apple ImageWriter II
• Apple ImageWriter II General Maintenance
• Apple ImageWriter II Documentation