Tantalum Capacitors

[rjb]

average was 100 boards a day. best record was 300 boards a day...

So we're talking production testing, right?
I hope you weren't doing an average of 100 repairs a day.
And I sure hope you weren't doing an average of 100 field returns a day.

-rb

[cjenrick]

not production, troubleshooting.

if you do the same circuit over and over, year after year, you pick up speed.

in the early days the boards were hand stuffed and hand soldered. so there was some fallout.

we could remove an 8 pin opamp in about 15 seconds, twist the chip off the leads with needle nose, heat the pins four at a time and slam the board down on a piece of cardboard before the solder hardened, can't spend all day rebuilding a solder sucker.

de-soldering station? don't make me laugh.

[bob p]

...we could remove an 8 pin opamp in about 15 seconds, twist the chip off the leads with needle nose, heat the pins four at a time and slam the board down on a piece of cardboard before the solder hardened, can't spend all day rebuilding a solder sucker.

de-soldering station? don't make me laugh.

That reminds me of a conversation with a TSA baggage inspector:

"We can open any locked bag in about 15 seconds using the BF Screwdriver. Twist the latches off of the hinge with pliers and toss them into the metal recycling hopper, can't spend all day opening a suitcase.

TSA-compliant keys? Don't make me laugh. The BFS opens everything."

[Justin Thomas]

Jobs the BFS has done:

Screwdriver
Chisel
Hammer
Prybar
Toilet Snake
Cap Discharger
Fingernail Cleaner
Socket Holder cuz I'm too lazy to get a ratchet
Drum Stick
Air Hole Maker
Oil Filter Removal Aid
Staple Remover
Speaker "Modifier" (okay, that one was unintentional)
Slim Jim
Lock Remover
Car Jack Lever
Paint Stirrer
Coffee Stirrer
Fire Poker
Tire Deflator (also unintentional)
Disciplinary Aid
Rust Remover
Outlet "Tester"
Others?

Justin

[eschertron]

Gosh, Justin! You and your Best Friend Screwdriver sure have seen a lot together

[Chuck H]

Jobs the BFS has done:

Screwdriver
Chisel
Hammer
Prybar
Toilet Snake
Cap Discharger
Fingernail Cleaner
Socket Holder cuz I'm too lazy to get a ratchet
Drum Stick
Air Hole Maker
Oil Filter Removal Aid
Staple Remover
Speaker "Modifier" (okay, that one was unintentional)
Slim Jim
Lock Remover
Car Jack Lever
Paint Stirrer
Coffee Stirrer
Fire Poker
Tire Deflator (also unintentional)
Disciplinary Aid
Rust Remover
Outlet "Tester"
Others?

Justin

LMAO

"Disciplinary Aid" That's my favorite

[olddawg]

I remember tantalum caps being used in a lot of discrete FM receivers back in the 1970s, especially car stereos. For some reason replacement with an electrolytic cap of the same value, even for tests, would never work at all. The tats used to get thermally intermitant and we troubleshot them a lot with a can of freeze.

[TimmyP1955]

When I was in the hi-fi biz in the late 80s/early 90s, one of our brands' preamps had tantalums, of which I replaced a fair number owing to leakage causing scratchy pots. Another brand changed from tantalums to electrolytics.

[cjenrick]

from http://www.kemet.com/Lists/ProductCa...aLdPerChar.pdf

[Chuck H]

In my tests I subjected the Kemet tants to about twice their rated voltage before failure. One unit failed at a reverse voltage just over the rated forward voltage. Also, I once installed the same Kemet tants backwards in an unusual layout. Being in cathode circuits the 15V rated caps probably didn't see more than +2V and they not only didn't fail, but they performed as normal. When I discovered the error I removed the caps. drained them somewhat slowly through a resistor, tested them for value and then reinstalled them correctly. Those caps are still working fine nine years now.

I don't think I'd use a tant close to it's rated voltage or in any AC circuit where near rated inverse voltage could occur. I've had no trouble with them so far though. And I've also not heard of any trouble with the ones installed in a hundred thousand Mesa products.

I'm interested in these high UF ceramics though. I'd throw my remaining tants at a moving car if I thought something less sneered upon was available.

[Mick Bailey]

Here's the full analysis from Kemet regarding cap failure modes. I don't disagree that short-circuit is most common, just as shorts are most common with SS rectifiers. This doesn't preclude any other possibility.

https://www.google.co.uk/url?sa=t&rc...qe4ViJpDuG5HDQ

[g1]

I don't disagree that short-circuit is most common, just as shorts are most common with SS rectifiers. This doesn't preclude any other possibility.

That's what I thought as well. "Dominant" to me only implies a majority, or more than half of failures. Not really exclusive.
Interesting though, that for tants, even opens will have probably started as shorts.

[Enzo]

Like anything else, the dominant failure mode of output transistors is E-C shorts. Certainly I have replaced many with C-B shorts too. But E-C is what I expect to see.