tom . hornberger on 13 Jul 2006 03:23:21 -0000


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Re: [PLUG] OT: SMD capacitor


On Wednesday 12 July 2006 22:47, Eric Hidle wrote:
> An electrolytic would be fine, but an SMD would be preferred to a
> radial....
>
> Polystyrene caps can run $5-$10.... low ESR caps can be a tad much...
>
> It takes a LOT to break a component off of a board. It doesn't happen
> w/o a lot of force..
> E
>
> gyoza@comcast.net wrote:
> > Thanks.  That really narrows it down.  I see that Mouser has some for
> > about $2.22 each.  (Expensive for caps, isn't it?)
> >
> > So, I should really avoid a electrolytic cap?  I have a 16V, 100uF and
> > 35V, 47uF available.  Or should I just return this card to the ebay
> > seller?
> >
> > I'm still wondering how a component could be knocked off the board at
> > both ends *and* one lead become completed broken off the component.
> > Could a loose heatsink/fan moving about during shipping do that?
> >
> > Eric Hidle wrote:
> >> Judging from the location, it doesn't look like a DC-DC output cap,
> >> but rather a bulk supply cap for the graphics processor. The DC-DC
> >> converters are nestled in that jungle of tin cans at the up-end of
> >> the board. That said, it could very well be a tantalum... 16VDC is a
> >> pretty high voltage for a solid polymer cap in that large a
> >> capacitance...
> >>
> >> Anyway, check out AVX TPS series caps for a replacement... they're
> >> probably available at digikey in onesies... perhaps a TPSD476M016
> >> E
> >>
> >> gyoza@comcast.net wrote:
> >>> Here are pictures of the capacitor.
> >>> http://reddragoncanoeclub.org/paul/9600/
> >>>
> >>> The card is just to show the location and relative size of the cap.
> >>> The only difference is that my cap is black and my board is green.
> >>> heh.
> >>>
> >>> I was assuming the cap is tantalum.
> >>>
> >>> Eric Hidle wrote:
> >>>> What package is the bad capacitor in and what chemistry was it?
> >>>> Chances are it was a low-ESR polystyrene or aluminum-polymer cap,
> >>>> in which case you do not want to replace it with just any
> >>>> off-the-shelf tantalum or electrolytic capacitor. The DC-DC
> >>>> converters on video cards are ultra-clean and depend upon a very
> >>>> low amount of resistance in the output caps to minimize ripple.
> >>>>
> >>>> Was this thing a round tin can?
> >>>> E
> >>>>
> >>>> gyoza@comcast.net wrote:
> >>>>> Nevermind.  heh.  I will try the radial capacitor.  (I found
> >>>>> #electronics on Freenode.net)
> >>>>>
> >>>>> gyoza@comcast.net wrote:
> >>>>>> I have a Radeon 9600 Pro video card with a bad surface mount
> >>>>>> capacitor (C2).  I'm not sure of the value of it.  It's labeled
> >>>>>> "47" and "16V" which I read as 47uF, 16V.  Does that sound
> >>>>>> correct?  It is a black SMD capacitor with a white end to
> >>>>>> indicate polarity.  The size is roughly 7mm x 3.5mm x 2mm.  I
> >>>>>> need to identify it enough to replace it.  Would it be too wacky
> >>>>>> to use a huge radial capacitor to replace it?
> >>>>>> ____________________________________________________________________
<snip>

It's probably a Tantalum.  The 47uF, 35V will work OK as long as the footprint 
is the same.  Most of the Tants have the same footprint, just different case  
heights (makes board layout easier!)  I might have some 47uF, 16V at work, 
I'll check tomorrow.  The cap coming off doesn't surprise me, 63/37 solder is 
very soft and easily deformed.  If you need someone to solder it on I have 
access to the proper equipment at work.

HTH,
Tom
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