What tool is effective for determining if a problem is in the power supply?

A power supply tester is specifically designed to assess the functionality of a power supply by checking its output voltages and ensuring they are within the specified ranges. This tool simplifies the process of diagnosing power supply issues by providing a straightforward indication of whether the power supply is operational or failing. It is particularly effective because it directly tests the power supply’s output without requiring extensive technical knowledge, which makes it accessible for technicians performing routine checks or troubleshooting.

In contrast, while a multimeter can also measure voltages, it can be less user-friendly for quick checks of a power supply since it requires manual connections and interpretation of readings. An oscilloscope is more complex and is typically used for analyzing AC signals or understanding waveform shapes, making it less ideal for quickly testing a power supply. A network tester is designed for evaluating network connections and data transmission, which doesn't apply to power supply diagnostics. Therefore, the power supply tester stands out as the best tool for accurately determining issues within the power supply itself.