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On 3/11/2010 9:40 PM, Richard Bronosky wrote:
<blockquote
cite="mid:ced68de91003111840k300653f4pe680b398f7c3d121@mail.gmail.com"
type="cite">
<pre wrap="">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:
<a class="moz-txt-link-freetext" href="http://www.st.com/stonline/stappl/productcatalog/app?path=/pages/stcom/PcStComPartNumberSearch.searchPartNumber&search=D5NM5">http://www.st.com/stonline/stappl/productcatalog/app?path=/pages/stcom/PcStComPartNumberSearch.searchPartNumber&search=D5NM5</a>
The capacitor looks like a film capacitor (a milk chocolate chiclet
<a class="moz-txt-link-freetext" href="http://images.google.com/images?q=chiclet">http://images.google.com/images?q=chiclet</a>) 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.
<a class="moz-txt-link-freetext" href="http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=std5nm50">http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=std5nm50</a>
</pre>
</blockquote>
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.<br>
<a class="moz-txt-link-freetext" href="http://en.wikipedia.org/wiki/Types_of_capacitor">http://en.wikipedia.org/wiki/Types_of_capacitor</a><br>
Look towards the bottom.<br>
<br>
<h3><span class="mw-headline" id="Capacitor_markings">Capacitor markings</span></h3>
<h4><span class="editsection">[<a
href="http://en.wikipedia.org/w/index.php?title=Types_of_capacitor&action=edit&section=19"
title="Edit section: Numerical coding">edit</a>]</span> <span
class="mw-headline" id="Numerical_coding">Numerical coding</span></h4>
<p>Many capacitors have numbers printed on their bodies to indicate
their electrical characteristics and polarity.</p>
<p>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.</p>
<p>Sometimes the capacity, working voltage, and tolerance are printed
on the body without encoding: "1,000 µF 16V - 20% + 80%".</p>
<p>On smaller capacitors there is not enough space for full details to
be printed, so numerical or colour coding is used.</p>
<p>Some are indicated with xyz "J"/"K"/"M" v "V" where xyz represents
the capacitance (calculated as 'xy <i>× 10</i><sup>z</sup><i>), the
letters J, K or M indicate the tolerance (±5%, ±10% and ±20%
respectively) and "v" is the working voltage.</i></p>
<p><b>Example</b>:</p>
<p>A capacitor with the following text on its body:</p>
<p><b>105 K 330 V</b></p>
<p>has a capacitance of 10×10<sup>5</sup> pF = 1 µF (±10%) with a
working voltage of 330 V.</p>
<p>A capacitor with the following text:</p>
<p><b>473 M 100 V</b></p>
<p>has a capacitance of 47×10<sup>3</sup> pF = 47 nF (±20%) with a
working voltage of 100 V.</p>
<br>
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