When a Death Cap Commits Suicide...

[Dave Curtis, dB AudioTech]

...it tries to take it's owner with it.

The customer flipped the polarity switch, got a nasty shock and heard a loud pop. The amp worked after that, but he wanted to make sure it wasn't screwed up, or going to kill him.

This had an OEM 3-wire cordset (and receptacle) on it; before Ampeg phased out the polarity switch (it's a '74 V2). I finished the phase-out process on this amp. ;o)

And that, boys & girls, is the reason "safety" caps were invented.

[Daver]

Yikes! That blow'd up real good!
Dave

[trem]

"A capacitor is two conductors, separated by the dielectric".... "Oh wait a minute, there's a good example right here."
Holy Cow!!! Looks like an air-bag went off.

[jrfrond]

There's a reason why I yank these bastards out of every amp that comes across my bench and perform a 3-wire conversion. They are really an accident waiting to happen. I get bit MANY times by hot chassis, but my body is used to it by now!

[tedmich]

wow totally unspooled like a roll of TP! Haven't seen that since I ran my Vicor 300VDC DC/DC converter with no load....last week!

I just removed two nice Blackcat 0.047/1kv death caps off an old "Diablo" +/-15v 16A power supply before they 'slpoded like that; their next job will be more civilized!

[Dave Curtis, dB AudioTech]

Ditto.

Except... At the behest of a good customer of mine (and against my better judgement; I ain't no old radio guy), I took in a '50 Zenith (hot chassis) radio to "get working". I replaced all the 'lytic and wax caps, using approved safety caps for those that were on the AC line. It's waiting for the ride to Kennebunk and reinstall.

[tedmich]

the "approved caps" just go open on failure right? Not tants right

[Gtr_tech]

Ha! I just dug the same thing out of an Ampeg V4B of the same vintage. This one looked more like a chinese yoyo....rather mild blowup. I dunno why they left those in there. Since it looks like it was 3 wire to begin with....coulda saved a few cents per unit.

[Dave Curtis, dB AudioTech]

the "approved caps" just go open on failure right? Not tants right

Right. Peavey (for one) uses them for across-the-line and line-to-ground applications. They're the ones with all sorts of listing agencies' logos on them (CSA, UL, etc). Smaller ones are ceramic, and larger values are film.

ABC's of Safety (Interference Suppression) Capacitors for Tube Radios

[jrfrond]

AC snubber caps that are approved for line use nowadays contain a series current-limiting resistor. If the cap shorts, you don't have a catastrophic situation. However, snubber caps are now used ACROSS the AC line, not from the line to the chassis. Electrical codes are much different now than they were in the 60's-70's.