A few words
about "computer grade" caps
I read with interest, the posting on forums and blogs about "computer grade" caps. Seems there
is a great deal of miss-understanding about what these are and if they are safe to use in audio
restoration projects. Here is my cut on the subject...

I have worked in the high-tech industry since the first IBM PC hit the streets in 1984. Some of
that time was as a repair tech, but I have always been the hands-on hardware type. I have
worked on all manner of computers, from room filling commercial systems to the cheapest
consumer grade PC.

In the beginning, there was no such thing as a "computer grade" cap... a cap was a cap, and
computers and related hardware were built like tanks. The computer systems from the 60's and
70's were large and consumed a lot of power. They required a great deal of "quiet" DC current  
and this was supplied through some very large canister type capacitors. These caps were built
to take a lot of heat, deliver a lot of current, and operate very quietly. They were of the highest
quality that could be produced, and became known as "computer grade" caps.  This label is still
used today to describe these large canister type capacitors. Although they are rarely used in
computers today, they have found use in some very high-end commercial electronics.... Power
supplies, radiology, detection systems, etc. They are still very high quality caps and the cost
reflects this ($20 - $300 each).

The quality issues related to capacitors started back in the late 90's. Beginning in the early 80's
"mass marketing" concepts began to take hold. The computer age was just getting started and
these electronic devices fit into the mass marketing concepts well. By the 90's the "consumer
electronics" machine was in full swing and driving costs down was central to this theme. This
resulted in component manufactures finding ways to make components (including capacitors) in
the cheapest possible ways. The marketing pressures to lower costs left the door open for some
not-so-honest companies to produce some very bad capacitors (some used stolen information,
and you can read about this on the web at
http://en.wikipedia.org.wiki/Capacitor_Plague). But
regardless of who was selling and who was buying, there emerged a market for cheap
capacitors. Many of these cheap capacitors found their way in to consumer PCs and other
computer controlled products. This set the stage for some real quality issues. Enter the late
90's... where PC's and other electronics, fell victim to this inevitable situation. A rash of failures
related to capacitors gave a new and different meaning to the term "computer grade" capacitor.

Consumer products are designed to be disposable and to have a limited life (3 - 5 years) and  
components for such cost structures exist. However, capacitors had a history of being reliable
devices and the dangers of buying the cheapest ones on the market were not apparent. So
with this in mind, I don't think any of the computer manufactures gave a thought as to how long a
cheap cap would last, or that the pressures to lower costs would result in such unethical
practices among component providers.... until it bit them in the back side. This is a lesson
learned by most reputable manufactures now.

I have to tell you... in my experience, the problems with bad caps was almost entirely contained
within consumer grade products. The commercial system did not see the issues of bad caps
often. Work stations, commercial computers, and hardware... are built to high standards and
the best components were generally used. When a company has mission critical data (payroll,
accounting, product designs, etc) riding on a computer, reliability becomes a very serious
business. I serviced a lot of commercial systems, and by far, the biggest issues were from
mechanical ware.... moving parts failed.  The other big issue was chip failures (Which can be
caused by a list of things that I won't get into here, but suffice it to say that none of which are
related to capacitors). The paradigm that drove commercial systems/products was different
than that for consumer products. This provided a "cheap" filter that kept the problem parts out,
and prevented the "Capacitor Plague" from becoming much of a problem in this market.

Because of the issues seen in the late 90's, some are using the term "computer grade" to
describe cheap, low quality capacitors.... to the contrary, most computers today use (and
require) a higher quality cap then say... toys, consumer quality Audio/Video equipment,
appliances, TVs, etc.  So the term is a bit misleading. As the speed of computers increased and
the electronics shrank to smaller and smaller sizes, the need for components that ran faster and
quieter, and to do it in hotter, smaller spaces was required. Capacitors are no exception to this.
Capacitors have improved greatly. So don't let this confuse you. You need to read this phrase in
context of the discussion. Computer grade cap are generally of a higher quality then the low cost
caps used in toys, and entry level consumer electronics. The use of the term "computer grade"
as used by manufacturers and resellers, usually indicates a higher grade cap. These are not the
ones designed to satisfy the "cheapest" consumer cost structures.

When buying capacitors, remember the lessons taught by the computer manufactures...
you get
what you pay for!!!
Buy the cheapest cap and you may buy junk. Stay with known brands
that have been in the business of making caps for a while and you will most likely get
good quality.
Don't buy the cheapest until you have read the specs sheet. Remember,
consumer products still only have a life of 3 -5 years and there are components that are
designed for this cost structure. Many spec sheets (but not always) will state "for consumer
electronics" and you can bet that life expectancy was not part of that product's design criteria.
However, with that said.... barring mistakes in manufacturing or design, even a cheap cap from a
reputable manufacture, will do what it is supposed to do for a number of years, and most likely...
many years.

So don't let the term "computer grade" scare you off. Some of the finest quality components
today were designed specifically for the demands of computer systems. What you really need to
understand is:

1) The specific market the component was designed for. This can be tricky, but
filter out capacitors aimed at toys and entry level electronics.

2) Who the manufacturer is. Even though some highly regarded
capacitor manufactures have had mistakes, they are few and far
between. When you produce millions of capacitors in a single batch,
they know, there is no such thing as a "small" mistake. If bad caps
get out on the market, it's a big deal... the kind that can ruin a manufacturer's
reputation. So, among the reputable manufactures, quality is a big deal.
Stay with the major brands and you will get good quality.
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