220-1101 Question 184
Single answerTouch screen/digitizerA user brings in a Windows tablet after dropping it. The display turns on and shows the desktop normally, but the user cannot tap icons or swipe on the screen. An external USB mouse works without issue, and there are no visible display artifacts. After updating the operating system and rebooting, the problem remains. Which component should the technician focus on replacing first?
- A
The LCD panel
- B
The digitizer
- C
The inverter board
- D
The video cable
- E
The GPU
Show answer and explanation
Correct answer: B
Explanation
This scenario tests the ability to distinguish between display output problems and touch-input problems on a mobile device. In CompTIA A+ Core 1, technicians are expected to identify that the touchscreen function and the visual display function can fail independently. A tablet that shows a normal image but does not respond to touch most strongly indicates a failed digitizer rather than a failed LCD. This aligns with standard mobile device troubleshooting practice: first identify whether the issue affects video output, input, or both. If only touch input is affected after physical damage, the digitizer is the primary suspect. Manufacturer service documentation for tablets and 2-in-1 devices commonly separates the LCD/display assembly from the touch digitizer, though in some models they may be fused and replaced as one assembly.
- A. Incorrect.
Incorrect. The LCD panel is responsible for displaying the image. In this scenario, the desktop appears normally and there are no visual defects such as lines, discoloration, or no image. That indicates the display portion is functioning, even though touch input is not.
- B. Correct.
Correct. The digitizer is the layer that detects touch input on a tablet or touch-enabled screen. A device can still display video correctly while touch input fails if the digitizer is cracked, disconnected, or damaged from impact. This is the most likely failed component based on the symptoms.
- C. Incorrect.
Incorrect. Inverter boards are associated with older LCD systems that use CCFL backlighting, not modern tablets with integrated touchscreens. Also, a backlight or inverter issue would affect screen illumination, not touch response.
- D. Incorrect.
Incorrect. A video cable problem would typically cause display issues such as flickering, no image, distorted output, or intermittent video. Because the screen image is stable and normal, the problem is not most likely the video cable.
- E. Incorrect.
Incorrect. A GPU problem would usually affect image rendering, cause artifacts, crashes, or prevent proper display output. Since the external mouse works and the image is normal, the graphics processor is not the most likely cause of touch-only failure.