Overheard a guy at the retro shop say his old Mac SE power supply exploded

I was at a local electronics shop yesterday picking up some caps for a Tandy 1000, and some guy was telling the owner his Mac SE smoked out after he plugged it in without checking the PSU first. He said it made a loud pop and smelled like burnt plastic for hours. It got me thinking - how many of us just assume old gear is safe to plug in right away? I always test with a dim bulb now, but maybe I should push that more. Has anyone else had a power supply fail bad like that after sitting for years?

2 comments

2 Comments

hugo_ellis9d ago

Yeah actually that's not quite right about the dim bulb tester being the main thing. A dim bulb tester just limits current so you don't blow stuff up right away, but it won't tell you if the PSU is gonna explode. You gotta let the old caps reform first by plugging it in through a variac or just using a slow power up over a few hours. I've had a Mac SE PSU that sat for fifteen years and the main filter cap was basically a dead short when I first checked it. If I had just plugged it in with a dim bulb it might have still popped because the bulb only limits so much. You really need to check for bulging caps and physical damage before you even think about applying power.

henry_kelly549d ago

Yeah I read somewhere that some old tube amp guys swear by just leaving the thing unplugged for a day after you first power it up through a variac, something about the caps soaking up the voltage slowly. Sounds like you had a close call with that Mac SE, I've heard those old switchers are nasty when they fail. I remember a guy on another forum saying he had a filter cap pop like a firecracker and it scared the hell out of him.