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when a capacitor becomes a cannon

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Old 02-26-2012, 08:47 PM
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Default when a capacitor becomes a cannon









A 600v cap in an old Teaberry boat anchor. Was working fine I was listening to some locals on 11 while wiring up a mic for it to test TX and all the sudden BOOM! What could cause this, it had only been 8 years since the radio had last been regularly used? Fortunately I grabbed the plug within seconds after and it kept receiving the entire time.
The foil that shot out across the board was about a foot long.


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Old 02-26-2012, 09:33 PM
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somethings I shoot stuff across the room out of my foot long...

but for real that is wild.
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Old 02-26-2012, 09:58 PM
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It's called "Rapid Energetic Disassembly". It often occurs in high-voltage capacitors such as this - ones that have seen more than a few years of service.

Doesn't have to be an electrolytic capacitor, as this shows. It's often a good move to replace ALL capacitors except maybe the disc ceramics after 20+ years. They won't all go bad, but yours is the exception that proves the rule.
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Old 02-27-2012, 09:15 AM
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Quote:
Originally Posted by Beetle View Post
It's called "Rapid Energetic Disassembly". It often occurs in high-voltage capacitors such as this - ones that have seen more than a few years of service.

Doesn't have to be an electrolytic capacitor, as this shows. It's often a good move to replace ALL capacitors except maybe the disc ceramics after 20+ years. They won't all go bad, but yours is the exception that proves the rule.
IIRc, the old Sprague "Orange drops" were also failure-prone after a lengthy period of inactivity.

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Old 02-27-2012, 10:36 AM
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Sometimes a capacitor's life is short for no apparent reason. Other times something else fails and draws too much current through the capacitor and it blows. Surprises the hell out of you doesn't it? Just be glad it wasn't one of these beasts. They are about three inches in diameter,aluminum end plates, ceramic case and loaded with a sticky tar like substance. When they go bang they really go BANG!!. BTW I never did get all the tar cleaned out of the transmitter that it exploded inside of.
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Old 02-27-2012, 01:54 PM
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Quote:
Originally Posted by Beetle View Post
It's called "Rapid Energetic Disassembly". It often occurs in high-voltage capacitors such as this - ones that have seen more than a few years of service.

Doesn't have to be an electrolytic capacitor, as this shows. It's often a good move to replace ALL capacitors except maybe the disc ceramics after 20+ years. They won't all go bad, but yours is the exception that proves the rule.

Just think about the Rapid Energetic Disassembly of a 5 farad cap in the back seat area of a Honda Civic.
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Old 02-27-2012, 02:47 PM
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!!!!!!!!CAUTION!!!!!!LETHAL!!!!!
THAT OIL BLEW OFF IN A REAL FINE MIST!!! IT IS VERY VERY CONDUCTIVE!! And Make sure you wash it off of YOUR MULTIMETER!!

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Old 02-27-2012, 03:57 PM
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Quote:
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Just think about the Rapid Energetic Disassembly of a 5 farad cap in the back seat area of a Honda Civic.
yeah how come this kinda shit happens to me instead of someone who deserves it.

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