Examkin

Question

Difficulty: Very hardLaptop Display Components and Features

An IT technician completes a bezel and lid assembly replacement on a convertible touchscreen laptop. Following reassembly, the internal display renders clear video, and touch inputs register accurately. However, the user reports that wireless network reception drops significantly whenever the display lid is adjusted beyond a 90-degree angle, and closing the lid no longer triggers system sleep mode. Which of the following internal cable routing or component installation oversights is the most likely cause of these combined issues?

  1. The Wi-Fi antenna micro-coaxial cables were pinched in the hinge assembly, and the magnetic reed switch or hall-effect sensor cable was pinched or left disconnected.Answer
  2. B
    The display inverter board was installed in reverse, causing electromagnetic interference with the Wi-Fi card and disrupting the lid magnet signal.
  3. C
    The digitizer controller board was connected to an external DisplayPort Alt Mode header rather than the internal USB bus connector.
  4. D
    The main embedded DisplayPort (eDP) ribbon cable exceeded its signal bandwidth rating, degrading adjacent wireless frequency bands.

Answer

The Wi-Fi antenna micro-coaxial cables were pinched in the hinge assembly, and the magnetic reed switch or hall-effect sensor cable was pinched or left disconnected.
Laptop display assemblies contain several non-display components whose cables route through the hinges into the main chassis. These include Wi-Fi antenna leads (routed to the top of the display housing for maximum range) and the lid-closure sensor (a hall-effect sensor or reed switch that detects a magnet in the base). Pinching the Wi-Fi coax cables in the hinge mechanism causes mechanical strain and RF signal loss when the lid rotates, while a disconnected or pinched sensor wire prevents the system from triggering sleep mode upon lid closure.

Step-by-Step Solution

1
Analyze the symptoms reported after lid assembly replacement
Identified two distinct issues: wireless signal attenuation correlating with lid hinge movement, and failure of the system to detect lid closure for sleep mode.
Both Wi-Fi antennas and lid-closure sensors (magnetic reed switch / hall-effect sensor) route their wiring through the display hinges between the chassis base and lid assembly.
2
Evaluate component functions inside the laptop display lid assembly
Wi-Fi antenna leads are coaxial wires running up into the top bezel; magnetic reed/hall sensors monitor lid closure relative to a magnet in the palm rest.
Pinching antenna wires inside the hinge damages shielding or core conductors, causing signal loss when the hinge rotates. Disconnecting or damaging the sensor cable prevents sleep detection.
3
Eliminate misdiagnoses involving legacy components and incorrect bus protocols
Disregarded inverter board causes and external port routing errors.
Modern LED/OLED displays do not use CCFL inverter boards, and digitizer routing errors affect touch capability rather than physical antenna coax and mechanical/magnetic lid sensors.

Key Concept

Laptop Display Assembly Cable Routing and Auxiliary Components (Antenna Harness and Lid Sensor)
Rate this question

Topics

Laptop Display Components and Features

More questions from this topic