TIL to always test voltage under load when fixing power supplies

I wasted a whole afternoon swapping out a power supply unit in a desktop, thinking it was bad. The system still wouldn't turn on after I put in a new one. A buddy told me to hook up a dummy load to check if the voltage drops, and sure enough, it was a bad capacitor on the board. Now I test with a load every time, and it saves me from chasing the wrong fix.

3 comments

3 Comments

sanchez.dylan2mo ago

I've made that same mistake more than once, my bench is full of perfectly good power supplies I swore were bad. You only learn that lesson the hard way, huh?

grantb922mo ago

Wait what was the actual thing you missed? I'm trying to avoid filling my own bench with good parts.

dakota8632mo ago

My buddy spent a whole weekend swapping caps in a monitor, totally convinced the power board was fried. He even ordered a replacement. Turns out he never flipped the little physical power switch on the back. The look on his face was priceless. @grantb92, that's the kind of thing that'll haunt your bench.