[ale] need help identifying a capacitor

[Quentin Schander]

Capacitors have two major values by which they are rated: Capacitance, measured in Farads although values for practical capacitors are usually given in microFarads or picoFarads.  The other important value is the maximum voltage that can be sustained without causing breakdown of the capacitor.  Interpreting the markings on a capacitor can be fraught with difficulties.

>From your description, I believe you are talking about a mylar film capacitor.  The number 333 is decoded as follows.  The first two 3s are the value, the third 3 is a multiplier giving 33000 picoFarads or 0.033 microFarads.  I believe the 400 is the DC working voltage.  I am not sure what the "A" means but it may be a quality rating.

Fry's website shows a 250 Volt, 0.033 microFarad mylar film capacitor for 99 cents.  You might also try Ack Electonics which is located in NW Atlanta just west of the 75, 85 merge.

Quentin R Schander



>>> On 3/11/2010 at  9:40 PM, in message
<ced68de91003111840k300653f4pe680b398f7c3d121 at mail.gmail.com>, Richard Bronosky
<Richard at bronosky.com> wrote: 
> I have a highly proprietary power supply with a burnt mosfet that
> looks like it took out a capacitor with it. The mosfet is a:
> http://www.st.com/stonline/stappl/productcatalog/app?path=/pages/stcom/PcStC
> omPartNumberSearch.searchPartNumber&search=D5NM5
> 
> The capacitor looks like a film capacitor (a milk chocolate chiclet
> http://images.google.com/images?q=chiclet) with 333J<newline>400A on
> it. I've been looking for 333 jule capacitors but they all are rated
> for voltages, not amps... what should I be looking for? I'm thinking
> that since that mosfet is rated for 400v-650v, maybe I should get a
> 650v capacitor.
> 
> What do you think about the capacitor?
> 
> Where should I pick these up? I think I can get the mosfet from
> digikey for $9.31 if they can get it at all. I'm confused about the
> digi-reel thing.
> http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=std5nm
> 50