I have a 750 watt ATX power supply that I will be testing with a multimeter to make sure the right voltages are present. How can I make sure that I do this safely? Is there anything that's threatening my safety that I should be aware of before I go prodding away at the leads?
Is the power that the PSU provides through its connectors enough to cause injury?
Many novices seem to want to measure the current output capability of power supplies by setting their meter to read current, then connecting it directly across the power supply terminals. YOU MUST NEVER CONNECT AN AMMETER DIRECTLY ACROSS A POWER SUPPLY Doing so will cause very large currents to flow, and may permanently damage the meter, power supply, or user!
If you keep the meter in voltage mode, and are careful to not short the test leads or power supply wiring, you should be able to measure the supply voltages without any hazard.
Many PC power supplies (and other switch-mode supplies) require a minimum load to operate correctly. Be sure you have a suitable load connected during your tests (or any time the supply is on.)
Yes, but only if you screw up. The 5V rails in particular have double-digit currents, so be triply sure that your DMM is in voltage mode before measuring each time.
Im going to offer a frame challenge answer. From your comments it seems that even if the PSU did have a hardware fault you wouldn't have the ability to fully diagnose / repair it. Perhaps a simpler way of diagnosing this is just to try a different PSU and see if the PC works? Diagnosing a hardware fault will take far more than checking voltages are present. It is a good starting point but its knowing what to do with it after
Alternatively Have you considered using an off the shelf PSU tester such as this? Amazon Link
