Author Topic: when a capacitor is put in backwards?  (Read 3618 times)

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Offline algorithmTopic starter

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when a capacitor is put in backwards?
« on: July 29, 2014, 06:39:48 pm »
What happens when a capacitor is put in place backwards due to mislabeling?
I know they break down and/or pop off.
Im more curious about what happens to whats further down the line after that.
Could this current flow damage nearby components?
 

Offline Rigby

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Re: when a capacitor is put in backwards?
« Reply #1 on: July 29, 2014, 06:51:04 pm »
Well polarized caps cease working pretty quickly.

Any effect on other components will be determined by the circuit and the components in question.
 

Offline Neilm

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Re: when a capacitor is put in backwards?
« Reply #2 on: July 29, 2014, 06:57:05 pm »
Well polarized caps cease working pretty quickly.

Depends on the capacitor - I have seen some that lasted for quite a while. Indeed, I ended up having a unit go into production at work with a cap (tant I think) fitted incorrectly due to an issue with the pick and place file. Only found it as some of the early units had the power rail sag.
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Offline mariush

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Re: when a capacitor is put in backwards?
« Reply #3 on: July 29, 2014, 07:35:47 pm »
Quote
Could this current flow damage nearby components?

What current flow.

The capacitor gets damaged and either behaves like a short or it will break down without short and act like it's never there.

If it gets shorted, the power supply will see the capacitor as a load and something will eventually break down...  ohm's law , v = i x r ... so whatever segment in that loop has a smaller resistance it will burn up.
If it's open, then whatever's after the capacitor will receive the "unfiltered" power, as if there was never a capacitor in the first place.

 

Offline nadona

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Re: when a capacitor is put in backwards?
« Reply #4 on: July 29, 2014, 08:42:13 pm »
Quote
Could this current flow damage nearby components?

What current flow.

The capacitor gets damaged and either behaves like a short or it will break down without short and act like it's never there.

If it gets shorted, the power supply will see the capacitor as a load and something will eventually break down...  ohm's law , v = i x r ... so whatever segment in that loop has a smaller resistance it will burn up.
If it's open, then whatever's after the capacitor will receive the "unfiltered" power, as if there was never a capacitor in the first place.

+1
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Offline Phaedrus

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Re: when a capacitor is put in backwards?
« Reply #5 on: July 29, 2014, 08:45:56 pm »
Aluminum electrolytics explode. After all, they're pretty much just a steel can with some aluminum foil and salty, acidic water in them. Put them in backwards and they overheat. They overheat and the water boils, expands, and explodes the metal can. How long it takes to blow up depends on the reverse (or over) voltage applied, as well as the thermal mass of the part itself; bigger caps take longer to blow just like bigger pots take longer to boil.
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Offline simpson

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Re: when a capacitor is put in backwards?
« Reply #6 on: July 30, 2014, 04:12:45 am »
 

Offline algorithmTopic starter

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Re: when a capacitor is put in backwards?
« Reply #7 on: July 30, 2014, 07:20:18 am »
Luckily the one of my question did not blow. Just made a sizzle, might have been working up to blowing though.
Thanks for the replies everyone. Great stuff.
 

Offline JacobPilsen

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Re: when a capacitor is put in backwards?
« Reply #8 on: July 30, 2014, 12:46:31 pm »
 


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