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 Post subject: Capacitor blowup
PostPosted: May Wed 15, 2019 2:02 am 
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My first and hopefully last cap blast. I almost had to change my underwear. That’s all the paper under it. It was on for awhile then bang.


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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 2:27 am 
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Location: Ohio 45177
Bad cap or other factor?

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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 2:41 am 
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Location: Aurora, CO 80013
I had the same thing happen yesterday on my Scott AW12 AVC power supply. I recapped it last year and was working fine. I played only about 5 minutes then BOOM! and smoke. I looked under the power chassis and saw this mess.


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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 3:00 am 
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Joined: Nov Tue 14, 2017 5:09 am
Posts: 1870
Location: Austin, Texas
I once worked in a lab that had a cap can embedded in ceiling. It served as a warning that eye protection was required any time power was applied to an exposed elecrolytic cap.

Jay


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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 3:00 am 
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Location: Maryland 20709, USA
ktewell wrote:
My first and hopefully last cap blast. I almost had to change my underwear. That’s all the paper under it. It was on for awhile then bang.
The most common causes are:

- Capacitor installed backwards (reversed polarity). (Usually blows immediately on power-up.)

- Capacitor voltage rating too low. (More common if there's a time delay.)

- Not likely... AC on the capacitor due to wiring error or shorted rectifier.

- Less common... defective component
This is highly likely with chinese no-name parts, rare with reputable manufacturers.

- Leigh

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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 4:47 am 
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Joined: Aug Thu 27, 2015 5:07 am
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Location: Traverse City, MI 49670
My bet a shorted rectifier, globe 80s are notorious in my book. I avoid their use.


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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 5:23 am 
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Location: Powell River BC Canada
Could those be the type SE? Self emptying. :roll:

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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 10:13 am 
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Location: Ohio 45177
Maybe wonderful brand Fulyu quality capacitor, 1.49 for 10, free shipping. Buy now! Mail ship from Kahbum province. Allow 30 days for delivery. :mrgreen:

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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 11:52 am 
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Joined: Nov Wed 30, 2016 7:35 pm
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Location: Sunbury, Ohio 43074
It’s ok. Just send it back in and get the cardboard replaced

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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 12:47 pm 
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Location: Dayton Ohio
Ahh yes, it happens.
Even to the best of us :oops:

One that sticks in my mind is when i replaced a 10 uf 250V filter cap in a 1990s Zenith color TV backwards.
It actually worked and the TV played nicely for about 10-15 minutes, then KAPOW! It blew as I was making some adjustments.

If anyone claims they never made a mistake, then it means they've never done anything in their life! :lol:

-Steve

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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 1:07 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1152
Location: Wayside, NJ Monmouth
Funny one from one of my repair shops.


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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 4:08 pm 
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Joined: Aug Tue 24, 2010 8:56 pm
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Location: Northeast Florida
I've never had a modern electrolytic or film capacitor blow...maybe I've just been lucky? *shrug*

I have had some electrolytics that I installed 30 years ago go bad, however. No fireworks, just more hum than is normal

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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 4:39 pm 
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Location: La Mesa Califonia
High school taking electronic shop. Long receptacles hangs from ceiling to over the bench. Found a metal can capacitor with 2 lugs. I found the breaker box and turned off the receptacle. Stuck capacitor into the plug. Went back to breaker box and turned the power on. BAM ! filled the shop with smoke and paper flying. Can shot through the window. Teacher sent me back to the class room to read shop safety book.
Another time I had an old Philco Tranistone with broken case. Radio did kinda play but distorted and hum. I wired a switch to the AC line in cord to the paper filter capacitor. Switch was labeled "Don't Touch". Radio playing loud with distortion and hum. A student walked by and you guessed it. Flipped switch and KABANG !This time the teacher got a kick out of that. But was told Knock That Sh__ Off !


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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 7:42 pm 
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Makes me feel better hearing all the stories. But not safer..... LOL

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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 7:52 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1152
Location: Wayside, NJ Monmouth
Here is a cap that you never want to fail. It's 1 MF at 50,000 Volts


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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 8:30 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
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Location: Sunbury, Ohio 43074
Egads! Did you check it for leakage and ESR?

Looks brand new. Should be a shorting bar across that thing, or at the very least, an arc ;-)

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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 8:42 pm 
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Location: Central PA 16801
i have never had a "name brand" capacitor blow.

then again, i've only ever used "name brand" capacitors with their certificate of compliance on the receipt from mouser or digikey.

the only bad experience i've had was from a mouser house brand of Xicon. somehow, i got one by mistake in a pile of nichicons, but decided to use it anyway. five years later, it worked, but it leaked a lot of brown goo from the leads' entry points into the rubber. it never saw any surge and it was only seeing about half the voltage for which it was rated, 2xx out of 450. it only had (maybe) 50 hours on it in five years.

steve

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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 8:57 pm 
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Location: Wayside, NJ Monmouth
There is a shorting wire on that big caps. We use two to four of then in a Pulse Load for High Voltage Cap charge supplies. Have not had one fail yet. But don't want to be around if one does.


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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 9:23 pm 
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Location: Beaver Falls, PA. USA
It didn't explode, but I had a 1940s vintage "FP" type electrolytic capacitor "erupt" and start leaking electrolyte, while I was trying to reform it.

I did have one blow, in an old Zenith color TV, that was on the bench. Two wires touched, putting way too much voltage on the cap; when it blew, the stuff whizzed past my head, and landed in the middle of the shop floor.

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Last edited by Tim Tress on May Thu 16, 2019 12:39 am, edited 1 time in total.

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 Post subject: Re: Capacitor blowup
PostPosted: May Wed 15, 2019 9:57 pm 
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Joined: Sep Tue 30, 2014 6:08 am
Posts: 4687
Location: Norfolk, VA
wazz wrote:
Maybe wonderful brand Fulyu quality capacitor, 1.49 for 10, free shipping. Buy now! Mail ship from Kahbum province. Allow 30 days for delivery. :mrgreen:



$1.49 for 10 ???..........I predict Harbor Freight will soon be giving them away with any purchase......... :lol:

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