220-1102 Question 715
Single answerDisconnect power before repairing PCA technician is asked to replace a failed RAM module in a desktop PC that is still at the user's desk. The computer is powered on, and the user says putting it to sleep should be enough because the screen is blank. What should the technician do FIRST to follow proper safety procedures before opening the case?
- A
Put the computer into hibernation and remove the side panel
- B
Shut down the computer, turn off the power supply if it has a switch, and unplug the power cable
- C
Leave the system running but wear an anti-static wrist strap before touching components
- D
Press and hold the power button for 5 seconds while the system remains plugged in
Show answer and explanation
Correct answer: B
Explanation
The safest first step before repairing a desktop PC is to remove electrical power from the system. In practical A+ workflows, that means shutting down the OS properly, turning off the PSU switch if present, and unplugging the power cord before opening the chassis. Modern systems can still provide standby power to the motherboard even when they appear off or are in sleep or hibernation states. CompTIA A+ objectives emphasize following proper safety procedures when working inside a PC, including disconnecting power before servicing internal components. ESD controls such as wrist straps are also important, but they are used in addition to power isolation, not instead of it.
- A. Incorrect.
This is incorrect. Hibernation is a power-saving state, not a safe service state for opening a PC. Depending on the system, some power may still be present, and the machine is not considered electrically isolated. Opening the case before fully disconnecting power creates unnecessary risk to both the technician and the hardware.
- B. Correct.
This is correct. Before repairing or replacing internal PC components, the technician should perform a full shutdown, switch off the PSU if a rear switch is available, and unplug the power cable. This follows standard PC repair safety practices and helps prevent electric shock, damage to components, and accidental startup while servicing.
- C. Incorrect.
This is incorrect. ESD protection is important, but it does not replace disconnecting power. A wrist strap helps reduce static discharge risk, but it does not protect against energized circuits or standby power still present in the system. The misconception is treating ESD precautions as a substitute for electrical safety.
- D. Incorrect.
This is incorrect. Holding the power button may force a shutdown on some systems, but if the PC remains plugged in, standby voltage can still be present on the motherboard and power supply. This step alone does not fully isolate the computer from electrical power and is not the proper first action before opening the case.