[sdiy] Failure modes on bypass caps...

[Harry Bissell Jr]

OK... I'll bite
  
  Most bypass caps fail shorted.
  
  (why?)
  
  If the cap fails open... you may not notice the failure if common
  practice was followed and there are redundant bypass caps.
  System performance might be degraded slightly, but the chance of
  seeing it is slim.
  
  If it fails shorted, you will notice.  Tantalums are famous for failing shorted 
  and burning. Ceramics seldom fail, but if they do they might not be as spectacuar
  as the tantalum.  Electrolytics usually vent, or explode.
  
  I can't remember ever seeing a ceramic bypass cap failure that was not initiated
  by some other component failure. In fact I can't remember seeing a ceramic
  fail, period.  It can happen but I didn't see it.
  
  I heard of some 'bad batch of caps' that found their way into some production
  synths at some time in history...  but a defective batch should not posion
  the whole pool.  OTOH, who would use SSS CMOS chips (after their history).
  
  H^) harry

Aaron Lanterman <lanterma at ece.gatech.edu> wrote:  
I've been reading up the sage advice on bypass caps, and something started 
to worry me...

When caps fail, do they fail into "open circuits" or "short circuits?"

If the later, it could be scary if the cap runs from the power supply to 
ground...

- Aaron, working on the transition form theory to practice

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