Today I heard a loud bang that tripped the circuit breaker in my server room. It must have been really loud because I could hear it 2 rooms away through 2 heavy doors and it was like a firecracker going off right next to me.
Long story short, it narrowed it down to one PSU from one of the computers. It smelled like burnt rubber and was really hot even after ~40 mins of being turned off when I finally got to testing it. All the rest of the tech was thankfully fine.
Its an old server PSU, like 10+ years old so not really surprised it blew up. Its a 800W unit made by HP but I couldn't find any model identification on it.
The weird thing is, I opened it up to really make sure this is the thing that failed but on the inside, it looks totally fine. Tested the fuse – all good, all the caps look good, no charring anywhere. After around 10 mins of looking inside the burning smell had faded away too. Still though, its the only thing that won't turn on. I got the rest of the computer it was attached to back up and running with a replacement PSU.
At this point I'm just curious – what could possibly create such a bang and not leave a trace afterwards?
Best Answer
Lead batteries, used in a UPS, can explode violently due to hydrogen gas buildup.
Mechanical damage will be evident, since the battery encapsulation will have failed.
I put my money on this, if it can be heard from rooms away.
Diodes and traces can explode without much mechanical damage or residue. Yet they can sound like a small lightning bolt depending on the fault current capacity or in other words, the energy let through by the protection circuitry.
Electrolytic capacitors can rocket off a board, but they tend to poof a lot of smoke and crud. However, in a server the airflow might dissipate this quickly.
Tantalum and ceramic capacitors go up in flames. Not much bang.
Resistors will often show burning of the PCB first. Otherwise they've exploded on a surge condition, and they will be scattered around the enclosure, similar to diodes.
Fuses will only explode when selectivity or breaking capacity is improperly allocated.