As embarassing as this is, I just removed a PCI expansion slot cover that was next to the 5v pin of the SPDIF sound connector on the edge of a motherboard. The PC was operating.

At that moment, I smelled it, the "magic smoke", I may have touched that 5v connector with the PCI slot cover, being metal - and it was earthed to the case because it was still connected to it, you know the cheap cases that force you to remove these covers by breaking them out

Well, it was very acrid this smell, no smoke was actually visible, but this was that distinctive smell that comes from burning out small components on PCB's

I immediately switched the power off when it happened, rebooted and the PC boots......

I removed the board for inspection, no visual damage on either side of the board and I can't tell where the smell came from, it's not the PSU or graphics card or anything else, the smell was strongest over the PCI slots, no longer evident.

I'm not sure what to do next, I'm not even sure I shorted the 5v pin on the SPDIF connector, but it seems very likely.

This was a spare PC of mine that I've just spent days on, preparing it for online gaming for an associate

I'm sure you know the difference between the smell of components beeing cooked, and wire-insulation getting cooked.

The only reason I'd be thinking insulation, is that I'd  think  that a cooked component on the MB would render it dead. BUT.. I also seem to remember a mysterious cooking on an ancient ASUS MB running an Athlon XP2000 many moons ago.. that I never resovlved, and the computer kept right on himming for months.. Though I did discover, while trying to stick in a clunker computer, that one of the PCI slots was dead (couldn't get it to see an E-net card).

I'd go over all the wires and look for burned through insualtion.. then try something like a modem, or E-net card in all the PCI slots..  maybe pin it down..

Good luck..

Several possibilities here.. there can still be damage to the SPDIF circuit

do you use the SPDIF I/O system off the board?  most dont

Could be a trace between layers that started cooking.. most boards are 6+ layers now.. you only see 2 (front and back)

Seen many a power transistor or regulator give the puff-o-death in odor without the visual but still work

Johns right.. I did not mention the caps and that is a real possibility

but if its a cap on the 5v+ buss for SPDIF and you dont use it,. you may never see a problem

'the smell' is never good..  and fortunately sometimes what you toast is a component that you are not really using. Motherboards are loaded with support components that are not being used but if you activate a feature they show up

Thanks for the input guys. I still haven't thoroughly tested the board, will do it today, I needed a break and spent the time learning to fly R/C Helicopters  ..... but that's another story.

I won't be using the SPDIF output, and I was hoping the damage might be restricted to that circuit if that is indeed where the damage lay.

I'll get to testing this board now  


JBaymore wrote on Oct 15^th, 2008 at 10:18am:


Well, I appreciate that sentiment, along with the others (above) of questionable (or obvious) inspiration

Oh, and thanks for the link to your homepage F, very informative   ...  ....    .....  

Haven't heard the term "magic smoke" in ages. And yes, I am referring to electronics.

Mushroom_Farmer wrote on Oct 16^th, 2008 at 6:29pm:


You obviously haven't been to San Francisco since the '70s then, Mush...

...they also consumed large quantities of the Mushroom variety, involving much "Magic"... ...!

F.... ... ... ...!

Beef Casserole for Dins.....with Mushrooms.. ...!

Quote:




Wait wait wait....

If Congo is hitting the mushrooms and the magic smoke Alex could be right