How do I troubleshoot the Studio Display 17-in.?

This article covers repair procedures for authorized service providers on selected Apple products, but we have published them in the Knowledge Base for the general public for educational purposes. At this time, there are a limited number of repairs that a customer can perform and these are covered under the customer installable parts program http://www.info.apple.com/installparts . If you have not been authorized to perform these procedures, please contact Apple (800-APL-CARE in the USA) or your local authorized service provider to schedule a repair.

DANGER! This procedure exposes you to high voltages that can result in death or serious injury. DO NOT ATTEMPT THIS PROCEDURE IF YOU HAVE NOT BEEN CERTIFIED AS AN APPLE-AUTHORIZED TECHNICIAN.

Troubleshooting Studio Display (17-in. CRT, 16-in. viewable image size)

General

The "Symptom Charts" section included in this chapter will help you diagnose specific symptoms related to your product. Because cures are listed on the charts in the order of most likely solution, try the first cure first. Verify whether or not the product continues to exhibit the symptom. If the symptom persists, try the next cure. (Note: If you have replaced a module, reinstall the original module before you proceed to the next cure.) If you are not sure what the problem is, or if the symptom charts do not resolve the problem, contact Apple Technical Support.

First Checklist

Important : Many display modules returned for repair are found to be fully operational. Read this checklist before you return a module, and prevent needless module replacement and unnecessary time delays.

The Studio Display (17-in. CRT) is not compatible with all computers.

This display works with all Power Macintosh computers (except the Duo 2300) running Mac OS version 8.0 or later. The CRT raster will not always resemble a perfect rectangle.

CRT tolerances allow for some distortion. Additional distortion can be caused by magnetized metal objects (desks, file cabinets, etc.). Move the unit to a different location if you notice raster bowing or bent raster edges. You can also use the geometry controls in the On-Screen Display to optimize the shape of the raster. Jitter, faint lines, or screen movement can be caused by external interference such as electronic devices and fluorescent lights.

Fluorescent lights, other monitors, or electronic appliances such as coffee makers and copy machines can cause raster distortion. Move the unit to another room or building to help determine if external interference is the source of the problem.

Note : If the raster has shifted up/down or right/left only, adjust it using the geometry controls in the On-Screen Display (OSD). However, keep in mind that if you then move the monitor you may need to readjust the display. If the display changes (for better or worse) when you move it to another location, the environment is the source of the problem. Relocate the monitor or move the distortion-causing object.

A misadjusted screen can mimic the symptoms of deflection board or CRT failures. By performing the adjustment procedures, you might determine if one or. more of the adjustments is the cause of the problem. CRTs rarely fail. Needless CRT replacement can be prevented by checking display adjustments, checking the possibility of other defective modules, and accepting small imperfections in screen display. If you have any doubts about whether a CRT is defective, contact Apple Technical Support.

Symptom Charts

No raster with LED on

Check all exterior cable connections. Check for bent pins on the connectors. Tighten thumbscrews. If a video card is used, the video cable must be secured to the card.

If LED is amber, verify computer video signal by connecting known-good monitor.

Adjust brightness and contrast controls on the front bezel.

A screen saver may be activated. Move mouse or press any key to reactivate the screen.

Replace main deflection board and CRT/video board module. See "Main Deflection and CRT/Video Board Module" in Take Apart chapter. See Adjustments chapter for diagnostic adjustments that might be necessary after board replacement.

No raster with LED off

Press power button on display. Ensure that power cord is plugged in properly.

Check power outlet at the wall by plugging in an electronic device that works.

If the display is plugged into a computer, ensure that computer is on and power cord firmly connected.

Check cable connection between main deflection board and user controls board.

Replace main deflection board and CRT/video board module. See "Main Deflection and CRT/Video Board Module" in Take Apart chapter. See Adjustments chapter for diagnostic adjustments that might be necessary after board replacement.

Video-Screen flickers

Check monitor cable connections. Tighten thumbscrews. If a video card is used, the video cable must be secured to the card.

Check for external interference by moving the monitor to another location-preferably in the center of the room away from other devices. Refer to "First Checklist" in this chapter.

If using more than one monitor with a computer, move the monitors so they are at least 18 inches apart.

If a video card is used, check the refresh rate. Refresh rates below 60 Hz may cause flicker. See the video card manual to raise the refresh rate above 60 Hz.

Double-check items 1 through 4.

Replace main deflection board and CRT/video board module. See "Main Deflection and CRT/Video Board Module" in Take Apart chapter. See Adjustments chapter for diagnostic adjustments that might be necessary after board replacement.

Screen is blurred

Note: If the monitor is set at the highest screen resolution, some finely-detailed images and small fonts might appear blurry. In this case, try changing the screen resolution.

Check external and internal cable connections. Reseat connectors.

Adjust the H Convergence and V Convergence as described in "Checking Screen Color and Adjusting Convergence" in the Adjustments chapter.

Using the Display Service Utility, select the focus pattern, and adjust Focus (the two top controls on the flyback transformer). Refer to "Adjusting Focus " in Adjustments chapter.

Double-check focus and/or readjust if necessary.

Replace main deflection board and CRT/video board module.

See "Main Deflection and CRT/Video Board Module" in Take Apart chapter. See Adjustments chapter for diagnostic adjustments that might be necessary after board replacement.

Screen is too bright

Adjust brightness and contrast controls. See "User Controls" in Adjustments.

Check high voltage as described in "Checking High Voltage" in Adjustments chapter.

Check B+ voltage as described in "Checking B+ Voltage" in Adjustments chapter.

Adjust screen control on flyback transformer. Refer to "Adjusting Screen Voltage" in Adjustments chapter.

Replace main deflection board and CRT/video board module. See "Main Deflection and CRT/Video Board Module" in Take Apart chapter. See Adjustments chapter for diagnostic adjustments that might be necessary after board replacement.

Colors are too green, red, or blue, and the screen is unreadable

Check video cable connector and ensure no pins are bent.

Ensure that video cable is properly connected; tighten thumbscrews. If a video card is used, the video cable must be properly attached to it.

Ensure that the video card or computer video port is good by connecting a known-good monitor.

Reseat the cables connected to the CRT/video board.

Replace main deflection board and CRT/video board module. See "Main Deflection and CRT/Video Board Module" in Take Apart chapter. See Adjustments chapter for diagnostic adjustments that might be necessary after board replacement.

Rainbow effect when displaying full-white screen

Check for external interference by moving the monitor to another location-preferably in the center of the room away from other devices. Refer to "First Checklist" in this chapter.

Turn off display. Wait a few minutes and turn on display. Degauss exterior of display with a hand-held degaussing coil. (You can purchase a degaussing coil for about $25 at most larger electronic parts stores.)

Replace CRT.

Note: The CRT might have been subjected to severe impact that damaged the aperture grill.

Thin vertical lines on screen

Important: Do not confuse this symptom with horizontal lines on the screen (the next symptom).

Note: The Diamondtron CRT used in the Studio Display (17-in. CRT) has an aperture grill of very fine, vertical wires to enhance screen sharpness. Exposure to cold and or vibration can cause these fine wires to temporarily adhere to each other. This anomaly is inherent to this display when exposed to lower temperatures.

Remove jewelry from your hands and arms. Using the heel of your hand, use moderate force to impact the side of the display under the Apple logo on the right, then left, side.

If the lines persist after a few attempts to break the adhesion of the wires, place a soft cloth over the face of the CRT. Use a solid rubber mallet and light force to impact the center of the CRT face. You may increase the force applied with the mallet until you are approximately 12 inches from the face of the CRT.

If the lines persist, call Apple Technical Support (in the US, call 1-800-919-2775, option 3) for further troubleshooting instructions. Replacing a main deflection board and CRT/video board module will not resolve the problem.

Thin horizontal lines on screen
Displays larger than 15 inches with tron-style CRTs typically have two stationary wires, each about one-quarter to one-third of the way from the top and bottom of the display image. These supporting wires, which are thinner than a human hair, stabilize the aperture grill against shocks. The lines are common to all tron-style displays and are not screen defects. The lines cannot be adjusted out or eliminated by repairing or replacing modules in the display.

Geometry

Raster is too short, tall, narrow, or wide

Using the On-Screen Display, click the Recall icon. If the screen geometry worsens, refer to "Adjusting Screen Geometry" in the Adjustments chapter to make new geometry settings and save them in factory mode.

Adjust the width and height of the screen. See "User Controls" in Adjustments.

Replace main deflection board and CRT/video board module. See "Main Deflection and CRT/Video Board Module" in Take Apart chapter. See Adjustments chapter for diagnostic adjustments that might be necessary after board replacement.

Raster is not centered

Using the On-Screen Display, click the Recall icon. If the screen geometry worsens, refer to "Adjusting Screen Geometry" in the Adjustments chapter to make new geometry settings and save them in factory mode.

Check that the distortion is not due to environmental conditions. Move the monitor.

Adjust the horizontal position of screen. See "User Controls" in Adjustments.

Adjust vertical position of screen.

Replace main deflection board and CRT/video board module. See "Main Deflection and CRT/Video Board Module" in Take Apart chapter. See Adjustments chapter for diagnostic adjustments that might be necessary after board replacement.