[R-390] Electrolytic Caps

[Charles Steinmetz]

Blair wrote:

> I'd like to buy an inventory of Electrolytic Caps, and kits can be quite
> inexpensive from China via eBay. Are all brands dependable?

No, not at all.  And it's not just brands, it's also individual product 
lines within each brand.  China, Inc. makes a huge variety of 
electrolytic capacitors, from unmitigated junk to space-qualified parts. 
  You, or someone acting on your behalf, has to navigate this swamp and 
figure out which are which, and how to get what you need.  The ones that 
sell in small quantities for next to nothing on ebay or from far east 
exporters are the unmitigated junk.

Above, I'm talking about capacitors that are marketed honestly by the 
manufacturers (but NOT NECESSARILY by the middlemen between you and the 
manufacturers) as exactly what they are.  In addition to those, there 
are the outright counterfeits -- capacitors, invariably from the 
unmitigated junk catagory, packaged as products from reputable product 
lines, but that in fact have nothing to do with the brands and lines 
they appear to be from.

Sadly, counterfeiting of electrolytic capacitors is so rampant that even 
major distributors are victimized by the practice.  But at least if you 
buy from a major distributor, you can expect to get a recall notice when 
the distributor finds out it has 20 million bogus capacitors in stock 
(this happens reasonably quickly because the caps get sold to hundreds 
of companies, many of which qualify incoming parts and will discover the 
problem sooner than later).

We have gotten such notices from most of the major distributors, and it 
seems to affect about 2-5% of the (combined) major distributors' 
inventory (that's a WAG based on our own recalled orders and 
conversations with other users and distributors' sales engineers).  It 
is enough of a problem that savvy manufacturers have learned to buy 
'lytics well in advance, so they are still sitting on the shelf when 
they get the recall notice -- not installed in products that would then 
need to be recalled.

Best regards,

Charles