Went to a repair station in San Antonio last month and it changed my mind about bench testing PSUs

I always skipped bench testing power supplies before install. Just plug and pray type of guy. But I saw this place in San Antonio where they had multiple PSUs hooked up to a dummy load setup. The technician showed me how one unit was showing a steady voltage on a multimeter but dropped under load. That scared me straight. Now I run every single PSU through a quick load test before it goes in a panel. Super easy with a cheap resistor bank. Has anyone else had a PSU fail under load that tested fine at idle?

4 comments

4 Comments

nancy47520d ago

That San Antonio shop sounds like it really knew what they were doing. I remember talking to a friend who works in audio gear, and he told me he had a power supply that passed his multimeter check but couldn't handle a single amplifier channel without the voltage sagging bad. It's wild how a meter can lie to you if you're not loading it down. Makes me wonder how many "good" units I threw into builds back in the day that were actually on the verge of failing.

eric72320d ago

Has anyone else felt like a total goofball after realizing they've been skipping load tests? I'm embarrassed to admit I was the guy who'd just hook up a PSU, cross his fingers, and hope for the best. Last year I actually had a brand new unit that showed perfect voltage at idle but dropped by almost half when I hooked up a couple of old car headlights as a test load. Made me feel like a dentist who forgets to check for cavities before filling one. Now I've got a little resistor bank sitting on my bench that I use for everything. Your mileage may vary of course, but for twenty bucks it saved me from chasing a phantom issue that never would have shown up otherwise.

mila_flores820d ago

Oh man, I was exactly the same way. I used to think bench testing was mostly for overkill hobbyists or engineers who just liked tinkering. But after seeing a unit that looked perfect on a meter but completely caved under a real load, it really opened my eyes. That San Antonio shop must have had a solid setup to demonstrate that. I definitely don't skip that step anymore either, a cheap resistor bank is just too easy to not use for the peace of mind it gives you.

ray_miller4120d ago

That story about the bench test is something I can really relate to. I had a similar wake up call a few years back when a buddy of mine was troubleshooting a unit that tested just fine on his multimeter but couldn't handle a basic load test. It was an eye opener for sure, especially because he had been so confident it was good. I remember him saying it felt like getting burned by a simple mistake you thought you had under control. Since then, I've made it a point to always run a cheap load test myself, even for things that seem straightforward. It just saves you from chasing ghosts later on and keeps you from second guessing your work.