Over the last few years I've acquired quite a few consumer electronincs pcbs
including TVs, VCRs, stereos, etc, so when I discovered that I needed a
tantalum to repair some test equipment I was going to salvage a tantalum. I
couldn't find one anywhere, so I assume they're too expensive or too
unrelaible for high end consumer electronics. A couple of the boards were
from my personal stuff purchased new. One example is a MGA Mitsubishi rear
projection TV that operated flawlessly for nearly 20 years of daily use.
Most of my test equipment comes from hamfests and is surplus after becoming
obsolete and non-operative in less than 20 years. That leads me to wonder
what the real story is behind tantalum capacitors. What do the experts have
to say?
tnx
hank wd5jfr

Henry Kolesnik wrote:

Over the last few years I've acquired quite a few consumer electronincs pcbs
including TVs, VCRs, stereos, etc, so when I discovered that I needed a
tantalum to repair some test equipment I was going to salvage a tantalum. I
couldn't find one anywhere, so I assume they're too expensive or too
unrelaible for high end consumer electronics. A couple of the boards were
from my personal stuff purchased new. One example is a MGA Mitsubishi rear
projection TV that operated flawlessly for nearly 20 years of daily use.
Most of my test equipment comes from hamfests and is surplus after becoming
obsolete and non-operative in less than 20 years. That leads me to wonder
what the real story is behind tantalum capacitors. What do the experts have
to say?
tnx
hank wd5jfr

They can have very good characteristics (small size, low esr, high
parallel resistance and good capacitance stability) but have some
strange failure modes if they are misapplied. Digikey sells a great
variety of them. I can seldom justify their cost in production
designs, but use them quite often in one offs.

--
John Popelish

In article , Henry Kolesnik
writes
Over the last few years I've acquired quite a few consumer electronincs
pcbs
including TVs, VCRs, stereos, etc, so when I discovered that I needed a
tantalum to repair some test equipment I was going to salvage a
tantalum. I
couldn't find one anywhere, so I assume they're too expensive or too
unrelaible for high end consumer electronics. A couple of the boards
were
from my personal stuff purchased new. One example is a MGA Mitsubishi
rear
projection TV that operated flawlessly for nearly 20 years of daily
use.
Most of my test equipment comes from hamfests and is surplus after
becoming
obsolete and non-operative in less than 20 years. That leads me to
wonder
what the real story is behind tantalum capacitors. What do the experts
have
to say?
tnx
hank wd5jfr
twere always regarded as more reliable than aluminum; however there is
a failure mechanism associated with the source resistance and how close
the operating voltage is to the maximum specified.
Modern aluminum can have very low esr and an adequate alternative to
tantalum.


--
ddwyer

John Popelish wrote:

Henry Kolesnik wrote:

Over the last few years I've acquired quite a few consumer electronincs pcbs
including TVs, VCRs, stereos, etc, so when I discovered that I needed a
tantalum to repair some test equipment I was going to salvage a tantalum. I
couldn't find one anywhere, so I assume they're too expensive or too
unrelaible for high end consumer electronics. A couple of the boards were
from my personal stuff purchased new. One example is a MGA Mitsubishi rear
projection TV that operated flawlessly for nearly 20 years of daily use.
Most of my test equipment comes from hamfests and is surplus after becoming
obsolete and non-operative in less than 20 years. That leads me to wonder
what the real story is behind tantalum capacitors. What do the experts have
to say?
tnx
hank wd5jfr


They can have very good characteristics (small size, low esr, high
parallel resistance and good capacitance stability) but have some
strange failure modes if they are misapplied. Digikey sells a great
variety of them. I can seldom justify their cost in production
designs, but use them quite often in one offs.

So in a production design, what would you use to get the equivalent
performance? An aluminum electrolytic in parallel with a ceramic?


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@ h@e@r@e@@
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goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 at hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
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F
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r

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m
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On Wed, 21 Jan 2004 17:26:14 -0600, "Henry Kolesnik"
wrote:

Over the last few years I've acquired quite a few consumer electronincs pcbs
including TVs, VCRs, stereos, etc, so when I discovered that I needed a
tantalum to repair some test equipment I was going to salvage a tantalum. I
couldn't find one anywhere, so I assume they're too expensive or too
unrelaible for high end consumer electronics. A couple of the boards were
from my personal stuff purchased new. One example is a MGA Mitsubishi rear
projection TV that operated flawlessly for nearly 20 years of daily use.
Most of my test equipment comes from hamfests and is surplus after becoming
obsolete and non-operative in less than 20 years. That leads me to wonder
what the real story is behind tantalum capacitors. What do the experts have
to say?
tnx
hank wd5jfr


We often use surface-mount tantalums on high-density, high-cost
boards. They are very reliable (don't dry out like aluminums) if used
carefully, but high peak currents can ignite them, so they are
generally a bad idea for bypassing power rails.

Polymer aluminums (don't dry out) or polymer tantalums (don't explode)
seem like a good idea, but I haven't tried them yet.

I think multilayer ceramics are pushing 100 uF these days.

John

"Watson A.Name \"Watt Sun - the Dark Remover\"" wrote:

John Popelish wrote:
(snip)
I can seldom justify their cost in production
designs, but use them quite often in one offs.

So in a production design, what would you use to get the equivalent
performance? An aluminum electrolytic in parallel with a ceramic?

A production design usually pays for the engineering necessary to
reduce the need for premium quality components. Your solution is
often a cheaper alternative to a premium quality tantalum.

--
John Popelish

I have a Racal 9301A where a tantalum must have caught on fire because all
that was left was 2 leads, some crisp blackish ash and a little hardened
crust on the pcb where it burned. There's probaby 10 other tants on the
board and one or more are shorted but still intact and I'm trying to find
the bads one/ones with least effort without a schematic. The other unit is
a Wavetek 188-S1257 where a tantalum had a dead short but was intact. I
repalced it with an electrolytic. The cap is on a 15 volt rail where I
think it shorted and took out the regulator. Ireplace the regulator with
what I assumed was a good one out of a new box but it was bad and it put 23
volts on the rail that had a 20 volt rating but no more failed. Sometime I
have good luck.
73
hank wd5jfr
"John Larkin" wrote in
message ...
On Wed, 21 Jan 2004 17:26:14 -0600, "Henry Kolesnik"
wrote:

Over the last few years I've acquired quite a few consumer electronincs
pcbs
including TVs, VCRs, stereos, etc, so when I discovered that I needed a
tantalum to repair some test equipment I was going to salvage a tantalum.
I
couldn't find one anywhere, so I assume they're too expensive or too
unrelaible for high end consumer electronics. A couple of the boards
were
from my personal stuff purchased new. One example is a MGA Mitsubishi
rear
projection TV that operated flawlessly for nearly 20 years of daily use.
Most of my test equipment comes from hamfests and is surplus after
becoming
obsolete and non-operative in less than 20 years. That leads me to
wonder
what the real story is behind tantalum capacitors. What do the experts
have
to say?
tnx
hank wd5jfr


We often use surface-mount tantalums on high-density, high-cost
boards. They are very reliable (don't dry out like aluminums) if used
carefully, but high peak currents can ignite them, so they are
generally a bad idea for bypassing power rails.

Polymer aluminums (don't dry out) or polymer tantalums (don't explode)
seem like a good idea, but I haven't tried them yet.

I think multilayer ceramics are pushing 100 uF these days.

John

Over the last few years I've acquired quite a few consumer electronincs pcbs
including TVs, VCRs, stereos, etc, so when I discovered that I needed a

Consumer electronics are costed down to the lowest possible level. If
they can use something cheaper, they WILL use something cheaper. A TV
set or VCR has had people go over the design hundreds of times with
BOMs and catalogs, checking to see if they can shave a penny here or a
penny there.

Computer equipment is a good source for tantalums - motherboards, hard
drive PCBAs, etc. Of course, it will be surface-mount

In article , "Henry Kolesnik"
writes:

Over the last few years I've acquired quite a few consumer electronincs pcbs
including TVs, VCRs, stereos, etc, so when I discovered that I needed a
tantalum to repair some test equipment I was going to salvage a tantalum. I
couldn't find one anywhere, so I assume they're too expensive or too
unrelaible for high end consumer electronics. A couple of the boards were
from my personal stuff purchased new. One example is a MGA Mitsubishi rear
projection TV that operated flawlessly for nearly 20 years of daily use.
Most of my test equipment comes from hamfests and is surplus after becoming
obsolete and non-operative in less than 20 years. That leads me to wonder
what the real story is behind tantalum capacitors.

Tantalum capacitors became a component item about 45 (or so) years
ago and originally favored in spacecraft and aircraft because they could
contain lots of electrostatic storage in a small space with ligher weight.
That was when PCBs were relatively new, quite new in spacecraft
electronics.

It hasn't been until the last decade or so that the cost of tantalum
capacitors has approached the level of improved electrolytic
capacitors of the same value. Tantalums are still relatively
expensive but they are good for SMT due to their smaller size;
its a trade-off between cost and overall system size in that case.

Inherent problems in tanatalum capacitors have been improved
since their initial debut as a component but so have electrolytic
capacitors and their manufacturing methods. One can purchase
FARAD-value low-voltage electrolytics now where once it was
not possible unless one had a room to put them in.

Len Anderson
retired (from regular hours) electronic engineer person

I wouldn't assume that just because your test equipment comes to you broken
is a result of tantalum caps -- perhaps your sample is skewed by buying at
hamfests instead of burgling active technology companies? Maybe if you only
acquired your home entertainment equipment from dumpsters you'd conclude
that aluminum electrolytics are bad?

I recently escaped from a company that does aero (but not space) systems.
They get mounted on aircraft and are expected to survive being shipped in an
unpressurized cargo hold at 50000 feet. At that altitude a wet aluminum
electrolytic will dry out, but a tantalum will be fine. There are even
wet-slug tantalums for high-altitude applications that will not dry out at
these altitudes.

The problems with tantalum are their fragility (we've had exploding caps on
our boards, with one manufacturer's part being fine and another being
horrid), cost, and the relative scarcity of tantalum. Does anyone remember
the Great Tantalum Shortage of a couple of years ago? One of the big
tantalum supplying regions is central Africa, and a combination of wars
reducing supply and increased demand led to some supply problems for a
while -- I remember that at least one of the manufacturers even came out
with a Niobium cap as a substitute.

"Henry Kolesnik" wrote in message
...
Over the last few years I've acquired quite a few consumer electronincs
pcbs
including TVs, VCRs, stereos, etc, so when I discovered that I needed a
tantalum to repair some test equipment I was going to salvage a tantalum.
I
couldn't find one anywhere, so I assume they're too expensive or too
unrelaible for high end consumer electronics. A couple of the boards were
from my personal stuff purchased new. One example is a MGA Mitsubishi
rear
projection TV that operated flawlessly for nearly 20 years of daily use.
Most of my test equipment comes from hamfests and is surplus after
becoming
obsolete and non-operative in less than 20 years. That leads me to wonder
what the real story is behind tantalum capacitors. What do the experts
have
to say?
tnx
hank wd5jfr