220-802 · Question #867
A technician suspects the AC voltage into a PC power supply is bad. Which of the following tools would MOST likely be used to confirm the diagnosis?
The correct answer is A. Multimeter. A multimeter is the correct tool for measuring AC voltage at a wall outlet or the AC input side of a power supply. It directly measures voltage, current, and resistance.
Question
A technician suspects the AC voltage into a PC power supply is bad. Which of the following tools would MOST likely be used to confirm the diagnosis?
Options
- AMultimeter
- BOscilloscope
- CCable tester
- DPower supply tester
How the community answered
(33 responses)- A91% (30)
- B6% (2)
- C3% (1)
Why each option
A multimeter is the correct tool for measuring AC voltage at a wall outlet or the AC input side of a power supply. It directly measures voltage, current, and resistance.
A multimeter set to AC voltage mode can measure the voltage coming from the wall outlet or at the IEC connector of the power supply, confirming whether the AC input is within the expected range (e.g., 110-120V in North America). It is the standard, portable, and affordable tool for this type of electrical diagnosis.
An oscilloscope visualizes waveform shape and frequency, which is far more than needed to simply confirm AC voltage presence and level.
A cable tester checks the continuity and wiring of data cables such as Ethernet; it has no function related to AC power measurement.
A power supply tester measures the DC output rails of the PSU (3.3V, 5V, 12V), not the AC voltage feeding into it from the wall.
Concept tested: Using a multimeter to test AC voltage input
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