CompTIA A+ Core 1 (220-1201)Hardware and Network TroubleshootingMedium
A user reports that their mobile phone's touchscreen is completely unresponsive, but the device still powers on, receives calls, and plays audio. The display shows images normally. Which component is MOST likely faulty?
- AThe LCD panel
- BThe display cable
- CThe GPU (Graphics Processing Unit)
- DThe digitizer
Show answer & explanationAnswer & explanation
Correct answer: D. The digitizer
If the display shows images normally and the device functions (receives calls, plays audio) but the touchscreen does not respond to touch, it indicates a failure of the digitizer. The digitizer is the layer responsible for detecting touch input, separate from the LCD panel that produces the image.
Why the other options are wrong
- A. A faulty LCD panel would result in no image, distorted image, or color issues, not just a lack of touch response.
- B. A faulty display cable could cause intermittent display issues, no display at all, or flickering, but it's less likely to selectively disable touch while maintaining a perfect image.
- C. The GPU is responsible for rendering images. If it were faulty, there would be severe graphical anomalies, no display, or system instability, not just a non-responsive touchscreen.
Mobile Digitizer Failure
A malfunction of the touchscreen layer that detects touch input, while the underlying display panel remains functional.
- Symptoms include an unresponsive or inaccurate touchscreen.
- The display itself typically shows images normally.
- Often requires replacement of the entire screen assembly (LCD+digitizer).
Memory trick: If you can see the screen but can't touch it, the digitizer has gone silent.