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astouffer 13th November 2009 02:15 AM

Bad day to be a capacitor
A buddy at work gave me a SoundTech mixer/amp to take a look at because it stopped working. The fuse was good but no continuity to the power transformer. The power switch is intermittent but luckily its a DPDT switch and only one side is wired. But anyhow when I started looking over the main amplifier board I spotted this freaky looking cap. The insides just look exploded out :yuck: A nearby wire has the insulation charred black from the heat!

Hopefully the blown cap and bad power switch are all thats wrong with this thing...

anatech 13th November 2009 03:00 AM

Hi astouffer,
Cool, a capacitor wearing a "dunce hat".

I've seen many like this over the years. Your power switch is probably the fault, but some power supply components may have suffered from the high noise coming from the arcing power switch.

What really helps is an MOV placed across the transformer primary. Right across the leads. If it shorts, the fuse will blow. The MOV will clamp the voltage spikes occurring when you turn the unit off. This will greatly prolong the life of the switch contacts.


wwenze 13th November 2009 05:26 AM

Ooooo so that's how the inside of a capacitor looks like.

Judging from the packaging, metal film?

destroyer X 13th November 2009 08:04 AM

That's the very first time i see this in 58 years
I could find leakage in those green ones, also errors in capacitance, also numbers not clear to read, but never exploded that way.



jaycee 13th November 2009 04:02 PM

Looks like something out of Aliens!!

kevinkr 13th November 2009 04:21 PM

First film cap I've seen fail this way in nearly 40yrs of tinkering, and a 30+ yr career. Pretty cool:D

destroyer X 13th November 2009 04:24 PM

Looks alike an Allien Sting
Very interesting..first time i have the chance to see that.



albin 13th November 2009 05:01 PM

Great picture
Instant Millimetric Waveguide Fluxcapacitor
....Great Scott!!!!!!!
I'm off to the shed
regards Max

tiefbassuebertr 13th November 2009 05:55 PM

very interesting!
such kind of destroy I know primarily from electrolytic capacitors, e. g.
There are many counterfeits, not only by semiconductors.
to find more photos about destroy caps, please fill in the term (key word) "bad caps" by google and use the image search

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