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Bad Chinese Capacitors

Iím seeing a disturbing trend.  For several years now I have seen many expensive electronic products die an early death due to poorly constructed electrolytic capacitors.  Nearly all of these bad devices are made in China.  Just last year I lost an expensive 1 year old HP printer due to a bad capacitor.  I traced the failure down to one bad capacitor, which failed shorted.  That shorted part killed a number of other parts.  So many parts were killed that repairing the printer was not practical.  A printer should last a lot longer than 1 year. 

Iím now reading that other people are seeing more and more of these vital components failing.  Some leak corrosive fluid.  Some have budging cases and still others have actually burst open.

Electrolytic capacitors have been around for some 100 years.  They are found in almost every electronic product made.  Their 100 year history has given manufactures plenty of time to get the process down to fine art.  In my early engineering life, seldom did these parts fail.  I have owned many TVs and radios which have continued working well past some 30 years.  Now, it seems that many products fail from defective capacitors in a very short period of time.

 

The illustration below shows how the classic electrolytic capacitor is made.  Two aluminum foils are separated by a paper spacer impregnated with a semi-liquid electrolytic material. The liquid maintains an aluminum oxide insulator surface on the foils.  The assembly is rolled up like a jelly roll and pushed into an aluminum can.  Rubber and plastic seals the assembly.  The oxide layer dramatically increases the surface area between the two metal plates, which allows these devices to offer a sizeable amount of capacitance in a small package. 

Now, as some of the photos below illustrate, there has been a rash of bad capacitors in expensive new electronic devices. 

The Chinese seem to be cutting corners and we all suffering from it.  In another example below, they have also been inserting smaller value capacitors inside larger aluminum cases.  This part will most likely fail in short order.
 
Capacitor cover pealing away     
                               Bulging and leaking capacitor
   
   Leaking Capacitors   Leaking Capacitors
   
  Split-Open Capacitors   Fake Chinese Capacitors

December 2009     Issue 4

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Envelope
Circuit
Diagnosis
Experimenter's
Corner
Good Idea
gone Badly
New Products Rants &
Raves
What the World
needs Now
Wily Widget



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