Apple Multiple Scan 17 Display Troubleshooting Guide

Apple Multiple Scan 17 Display (Apple data sheet photograph, 1994)

Fault-finding on the Apple Multiple Scan 17 Display from Apple's Service Source. Apple's own figure is that 54 % of the modules returned for repair worked, so its first checklist comes before any board change.

Read CRT Discharge Procedure before opening the display. Save the EEPROM before replacing the microprocessor board; see Apple Multiple Scan 17 Display General Maintenance#Saving the EEPROM.

First checklist

• The display is not fully compatible with every Macintosh and PowerBook. A missing screen resolution may be the computer, not the monitor.
• A CRT raster is never a perfect rectangle. Magnetised metal (desks, filing cabinets) adds distortion; move the monitor if the edges bow or bend.
• Jitter, faint lines and movement often come from electronic devices and fluorescent lights. Try another room or building.
• A misadjusted picture can look like a deflection board or CRT failure. Do the adjustments first.
• CRTs rarely fail. Accept small imperfections and contact Apple before condemning a tube.

Symptom charts

Apple Multiple Scan 17 Display symptom charts (Service Source pp. 12-20)

Symptom	Cures, in order
No raster, power light on	Check the video cable to the computer or video card; replace the main deflection board
Colour blotches at the edges of a white screen	Degauss with an external coil; move the monitor and degauss again. Caused by strong magnetic fields; board changes will not cure it
Oversized raster, menu bar cut off, adjustments have no effect	Replace the main deflection board, and check the microprocessor board revision: "-12" with a white mark or "-13" without one is updated; "-11", or "-12" without a white mark, needs replacing after saving the EEPROM
No power, power light off	Check the power cord and outlet; check the video cable; replace the main deflection board
Monitor shuts down	Check the video cable; do Apple's CRT test (below); if the CRT is not the cause, replace the main deflection board; replace the CRT/video board
Convergence indicator blinks or stays on (power light may blink)	Replace the microprocessor board after saving the EEPROM
Rotation indicator blinks or stays on	Replace the main deflection board
Size indicator blinks or stays on	Replace the main deflection board; the CRT/video board; the microprocessor board after saving the EEPROM
Centring indicator blinks or stays on	Replace the main deflection board; the microprocessor board after saving the EEPROM
Cannot download saved settings to a new microprocessor board	Check that the Display Setting Restore Utility version matches the one on the current Service Source CD; contact Apple
Vertical jitter	Move the monitor (interference from electronics, fluorescent lights or power lines is the usual cause); replace the microprocessor board after saving the EEPROM

CRT test

For a monitor that shuts down soon after power-up.

1. Remove the stand and rear cover, discharge the CRT and take off the EMI shield.
2. With the power off, put a non-conductive sheet (plastic or card) between the CRT/video board and the main deflection board.
3. Loosen the board's mounting screw and pull the CRT/video board straight off the tube neck, without twisting it, and rest it on the sheet.
4. Connect the monitor to a computer and switch on.
5. If the power light stays on, the CRT is defective. If the monitor shuts down immediately or after a few seconds, replace the main deflection board.

The test runs the monitor with its covers off; follow CRT Discharge Procedure before and after it.

Not a fault

The two thin horizontal lines across the picture are the aperture grille's support wires, present on all Trinitron displays larger than 15 inches. They cannot be adjusted out or removed by changing modules.

Related pages

• Apple Multiple Scan 17 Display
• Apple Multiple Scan 17 Display General Maintenance
• Apple Multiple Scan 17 Service Source
• Capacitor Failure Symptoms