220-1101 Question 185
Single answerInverterA user reports that an older laptop powers on normally and you can faintly see the desktop if you shine a flashlight at the screen, but the display appears very dark otherwise. An external monitor works correctly. After reseating the display cable, the symptom remains unchanged. Which component is the MOST likely cause of the problem?
- A
Failed LCD inverter
- B
Corrupted video driver
- C
Defective system RAM
- D
Failed Wi-Fi antenna cable
Show answer and explanation
Correct answer: A
Explanation
This scenario matches a classic backlight failure on older laptops that use a CCFL lamp and inverter board. A very dim image that is still visible means the LCD panel is generating the picture, but the backlight is not functioning. In A+ Core 1 objectives, the inverter is a key laptop display component to recognize in legacy systems. Best-practice troubleshooting is to isolate the issue by comparing the internal display with an external monitor and by checking for a faint image with a flashlight. If the external display works and the internal image is present but not illuminated, the technician should suspect the inverter or backlight rather than drivers, RAM, or wireless components.
- A. Correct.
Correct. On older laptops that use CCFL backlighting, the inverter supplies power to the backlight. If the inverter fails, the LCD can still produce an image, but the screen will be extremely dim and only visible under bright light or with a flashlight. The fact that an external monitor works also points away from the GPU and toward the laptop display backlight circuit.
- B. Incorrect.
Incorrect. A corrupted video driver typically affects image rendering on both the internal and external display, causes low resolution, artifacts, flickering, or failure to load the graphical interface properly. It does not usually cause a normal image to appear only faintly on the built-in screen while leaving the external monitor unaffected.
- C. Incorrect.
Incorrect. Defective RAM would more likely cause POST failures, random crashes, application errors, or failure to boot. It would not specifically create a dim-but-visible image on only the laptop's internal display.
- D. Incorrect.
Incorrect. A failed Wi-Fi antenna cable affects wireless signal strength and connectivity, not LCD brightness or backlighting. This is a plausible distractor because antenna cables run through the display assembly, but they are unrelated to the screen illumination circuit.