[mythtv-users] Busted pcHDTV HD-5500

Brian Wood beww at beww.org
Tue Jun 16 19:00:01 UTC 2009

On Tuesday 16 June 2009 12:48:39 Larry Sanderson wrote:
> > > From: Larry Sanderson <larry.sanderson at gmail.com>
> > >
> > > I have never seen a blown capacitor before, but google can
> > > help me there.  I
> > > think I'll try looking the card over one last time, clean
> > > the leads, and give
> > > it another shot.
> >
> > [OT]
> > Google 'capacitor plague'
> > I hadn't either until one of my LCD monitors died and I googled around a
> > bit. Pulled it apart and four of the six caps were popped.
> > Going to solder in $10.00 worth of caps and (hopefully) bring it back to
> > life.
> Interestingly enough, the board didn't have any cylindrical or disc shaped
> capacitors.  There were a bunch of tiny components soldered to the board
> labeled C012, C121, ... which might be capacitors, but they all looked
> fine.

It's the electrolytic capacitors that usually cause problems, and can be 
described as "cylindrical" or "can" type. These capacitors use a very thin 
chemical film as the dielectric, allowing much higher capacitances in a small 
package, due to the thin dielectric. This is also why the fail more often, 
the thin layer is more prone to puncture, and the chemical tends to break 
down over time.

Non-electrolytic capacitors are usually ceramic, plastic, mica or other 
thicker types of dielectrics, which means smaller capacitances. These usually 
look like "chips", with a white middle and metallic ends.

Non-electrolytics tend to be in the under 1 micro-farad range of capacitance, 
while the electrolytics are 1uf. and up. The rated operating voltage of 
electrolytics tend to be much lower than non-electrolytic units, usually in 
the tens of volts for electrolytics and hundreds or even thousands of volts 
for the non-electrolytic types.

It is extremely rare for non-electrolytics to fail, once they are installed 
and operating.

> For me, I guess the board is just dead.  No biggie - ordered a new board
> this morning.

Guess you're right, too bad though.

Brian Wood
beww at beww.org

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