220-1202 Practice Question: A customer reports that their computer is…

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Put on anti-static wrist strap and grounding mat.

  Why it's wrong here

  An anti-static wrist strap and grounding mat protect sensitive electronic components from electrostatic discharge (ESD), but they offer no insulation against the high-voltage AC mains inside a power supply. In fact, if a component is live, a grounded strap could even provide a low-resistance path for current through the technician, depending on the setup. The immediate hazard is potential electric shock, which is only eliminated by disconnecting the power source from the wall.

• ✓

  Unplug the power cord from the wall outlet.

  Why this is correct

  Unplugging the power cord from the wall outlet creates a physical air gap between the computer's internal power supply and the AC mains, eliminating the risk of a live 120V/230V line. This is the definitive first step because a soft-off via the power button or a switch on the PSU may still leave standby voltage present on the motherboard. Even though some capacitors can retain a dangerous charge, removing the cord is essential before any other safety procedure, such as discharging or opening the case.

• ✗

  Press the power button to discharge residual power.

  Why it's wrong here

  Pressing the power button while the cord is still connected draws power from the wall and can energize the system further, potentially worsening the fault that caused the emission. Even after unplugging, a single press cannot fully discharge the large filter capacitors in the power supply, which can hold hundreds of volts for some time. This maneuver is not a recognized safety step for eliminating shock risk; it is simply a quick way to drain the low-voltage rails, not the mains-side capacitors.

• ✗

  Wear safety goggles to protect eyes from debris.

  Why it's wrong here

  While safety goggles are essential PPE for tasks that generate flying particles, such as drilling or cutting, they cannot shield a technician from electricity, which poses the immediate lethal threat in a malfunctioning computer. If a component is emitting smoke, sparks, or arc flashes, the first and most critical action is to de-energize the equipment by removing its power source. Donning goggles may be advisable later during the inspection, but it does not address the primary hazard of a live power supply.

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