Spent 4 hours on a 'simple' power supply board just to find a cold joint under a cap

I had this old audio amp from a local band that kept cutting out, and the main board looked perfect under my loupe. I mean, I checked every trace and component, even swapped the main IC. Turns out the factory solder on one tiny filter cap was basically just touching the pad, and it only failed when the thing got warm. Who else gets stuck on these phantom issues that turn out to be the most basic soldering flaw?

2 comments

2 Comments

brown.gavin5d ago

Had a VCR board once that would reset every 20 minutes like clockwork. I reflowed the whole main processor section before I spotted it. The ground pin on a crystal oscillator had a perfect-looking solder ring, but the pad itself had a hairline crack you couldn't see unless you flexed the board. It's always the joint that looks the most solid.

anna_ross194d ago

Used to think a good visual check was enough for solder joints. That philosophy died after chasing a random reboot on a router for a weekend. The fault was a shiny, perfect-looking joint on a voltage regulator that had no actual bond.