[ale] need help identifying a capacitor

[Calvin Harrigan]

On 3/11/2010 9:40 PM, Richard Bronosky 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/PcStComPartNumberSearch.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=std5nm50
>
>
>    
I'm pretty sure the J refers to the tolerance..  From what you describe 
sounds like it's a .033uf 5% tolerance 400 volt polyester film 
capacitor.  Why do you think that the capacitor is bad, polyester film 
and ceramic capacitors are pretty resilient.  Chocolate chicklets...  
Hmmmm, not sure whether that'll be good or not.
http://en.wikipedia.org/wiki/Types_of_capacitor
Look towards the bottom.


      Capacitor markings


        [edit
        <http://en.wikipedia.org/w/index.php?title=Types_of_capacitor&action=edit&section=19>]
        Numerical coding

Many capacitors have numbers printed on their bodies to indicate their 
electrical characteristics and polarity.

Polarised capacitors for which one electrode must always be positive 
relative to the other have clear polarity markings, often "+" or "-" on 
one or both leads, a stripe, and different shape of the connection.

Sometimes the capacity, working voltage, and tolerance are printed on 
the body without encoding: "1,000 µF 16V - 20% + 80%".

On smaller capacitors there is not enough space for full details to be 
printed, so numerical or colour coding is used.

Some are indicated with xyz "J"/"K"/"M" v "V" where xyz represents the 
capacitance (calculated as 'xy /× 10/^z /), the letters J, K or M 
indicate the tolerance (±5%, ±10% and ±20% respectively) and "v" is the 
working voltage./

*Example*:

A capacitor with the following text on its body:

*105 K 330 V*

has a capacitance of 10×10^5 pF = 1 µF (±10%) with a working voltage of 
330 V.

A capacitor with the following text:

*473 M 100 V*

has a capacitance of 47×10^3 pF = 47 nF (±20%) with a working voltage of 
100 V.


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