4.2.1. Troubleshooting Video, Projectors, and Displays
š” First Principle: To diagnose display issues, you must first eliminate physical connectivity and input source selection as causes before investigating driver or hardware failures on the host or display.
Scenario: A user connects their laptop to a conference room projector, but the image on the screen is distorted and has a purple tint. You suspect a faulty cable is the most likely cause.
Technician's Diagnostic Path:
- Check Input Source: Verify the projector is set to the correct input (e.g., HDMI 1).
- Test the Cable: Replace the video cable with a known-good one. If the problem is resolved, the original cable was faulty.
- Isolate the Device: If a new cable doesn't fix it, connect a different, known-good laptop to the projector with the known-good cable.
- If the image is now clear, the problem is with the original user's laptop (likely a driver or video card issue).
- If the image is still distorted, the problem is with the projector itself.
ā ļø Common Pitfall: Not checking the display's own on-screen menu. The display itself has settings for input, brightness, and color that can be the source of the problem.
Key Trade-Offs:
- Resolution vs. Performance: Setting a resolution that is not the monitor's "native" resolution can result in a blurry or stretched image.
Reflection Question: You are troubleshooting a display issue. You have already tried a different, known-good cable and the problem persists. What is your next logical step to isolate the problem to either the computer or the monitor?