220-1101 Question 423
Single answerDim imageA user reports that their older laptop powers on normally and the desktop is barely visible, but the screen is extremely dark even when brightness is set to maximum. When you shine a flashlight at the display, you can faintly see icons and windows. An external monitor connected to the laptop displays normally. Which component is the MOST likely cause of this issue?
- A
Failed backlight or inverter in the laptop display assembly
- B
Corrupted video driver in the operating system
- C
Defective GPU on the motherboard
- D
Incorrect screen resolution setting
Show answer and explanation
Correct answer: A
Explanation
This scenario describes a classic dim image/backlight failure. A flashlight test is a common field diagnostic: if the user interface is faintly visible, the LCD panel is still receiving video data, but the screen illumination has failed. For A+ Core 1 troubleshooting, candidates should distinguish between image-generation problems (GPU, cable, driver) and illumination problems (backlight, inverter, display assembly). On older CCFL-backlit laptop screens, CompTIA commonly associates this symptom with a failed inverter or backlight. Best practice is to verify brightness settings, test with an external display, and then isolate the laptop display assembly components before replacing parts.
- A. Correct.
Correct. A very dim image that becomes visible when illuminated with a flashlight is a classic symptom of a failed backlight system. On older laptops with CCFL-based LCDs, this often points to a failed inverter or backlight lamp. On newer LED-backlit displays, it would more generally indicate a backlight circuit or display assembly issue. Because the image is still being generated, but not properly illuminated, the fault is with the screen's lighting rather than image generation.
- B. Incorrect.
Incorrect. A corrupted video driver can cause low resolution, flickering, artifacts, failure to load accelerated graphics, or display output issues, but it does not typically cause a faint but otherwise intact image that is only visible with a flashlight. The external monitor also works normally, which further reduces the likelihood of a driver problem.
- C. Incorrect.
Incorrect. A defective GPU would more likely affect both the built-in display and the external monitor, and could cause artifacts, crashes, no video, or intermittent display loss. In this scenario, the external monitor works properly and the laptop LCD is still producing an image, which indicates the graphics subsystem is functioning.
- D. Incorrect.
Incorrect. An incorrect resolution setting may make the display look stretched, blurry, or improperly scaled, but it would not make the image extremely dark while still faintly visible under a flashlight. Brightness and illumination issues point to the display backlight system, not display settings.