What's bst method of testing Tanytalium capacitors - diyAudio
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Old 29th April 2010, 08:22 PM   #1
gto127 is offline gto127  United States
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Default What's bst method of testing Tanytalium capacitors

I've never dealt much with tantaliums but have reason to suspect one of them may be culprit in a regulation circuit. There is no signs of cracks. I know several ways to check regular electrolytics would same rules apply?
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Old 29th April 2010, 08:49 PM   #2
amp_guy is offline amp_guy  United States
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I test them by giving them a hard squeeze with a big pair of pliers, if they break then they need to be replaced
But seriously they are so problematic that if they are not shorted now they soon will be.
And yes test them like you would an electrolytic.

Last edited by amp_guy; 29th April 2010 at 08:50 PM. Reason: missing sentance
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Old 29th April 2010, 11:55 PM   #3
gto127 is offline gto127  United States
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Could I replace them with a low leakage eletrolytics such as nichicon muse or are they too critical? The one with problem is in voltage regulator circuit but I noticed I have a ton of them around the DAC's which are PCM63's. Thanks Donald
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Old 30th April 2010, 07:54 PM   #4
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Default tantalum

I test tantalums by production date. More than 10 years old, suspect. The capacitors that started as tantalums in my 1968 production Hammond organ have all random dates, starting in 1973, so some of them were bad after 5 years. There were some 5 & 10 uf tantalums in there originally, I replaced them all with Aerovox ceramic caps. The +80 -20 tolerance on the ceramics had no bad side effects I can detect . There is no reason besides first cost to use an electrolytic or tantalum capacitor in 1`,2,3,5,10 uf below 50 WVDC unless it is a critical timing or filtration circuit.
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Last edited by indianajo; 30th April 2010 at 07:56 PM. Reason: poor wording
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Old 30th April 2010, 08:46 PM   #5
gto127 is offline gto127  United States
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The suspect tantalums passed both capacitance & esr tests. I may replace them anyway since they are at least 15 years old. One of them is 47uf so I doubt I would be able to find a ceramic that large. Is there a good replacement tantalum brand to buy or are they pretty much the same?
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Old 30th April 2010, 09:03 PM   #6
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Default capacitor purchase

If you matched ESR, size, tolerance, voltage rating, I don't know why I would ever buy another tantalum capacitor. They were a lot smaller than aluminum electrolytics in the seventies, but aluminum is 1/3 the size now. Since I keep my favorite equipment for decades (repairability is one criterea that most modern stuff fails, I can't wave solder) and I don't like doing work over again in 10 years, I buy aluminum electrolytics by projected service life. 5000 hours up at 105 deg is good, 500 hours or less at 80 deg bad. I notice when I get the long life ones they have nice looking seals around the leads. Really cheap electrolytics are not rated in hours, nor are American made Vishay Sprague, (TL) which I am partial to since some built by the predecessor company are still working fine in the harp circuit of my organ after 40 years. One vendor that shows the service life in their selector tables is Newark/Farnell. They also have a discount mark next to the cap if it is overstock or old- old is bad on electrolytics. Since the size of the cap can be gotten from the manufacturer's link in the on-line catalog, you can tell if an aluminum electrolytic will fit on your board before you order it. Watch tolerance on timing circuits, critical point frequency filters. For power supply filtering or bypassing hum to return at an input of an amp stage, +80-20 seems to work fine. The harp capacitors were 15 uf +_10% is one reason I didn't replace them, $5 each and value is important. I just bought a sack of 47 @ 25 V long life vishay spragues caps for a mixer that came in US made, to my delight as an unemployed former electronics specialist. Pro-grade motor drives mostly use Nichon electrolytic caps, 10 years next to an oven at high currents proves these expensive caps were really built.
Oh, self inductance measurement is important in caps for RF circuits, not very important for audio. Watch this if you are doing RF or fast computer circuits, one reason for tantalums that doesn't apply to the organs and sound equpment I am doing.
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Last edited by indianajo; 30th April 2010 at 09:12 PM. Reason: discuss inductance
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Old 30th April 2010, 10:09 PM   #7
gto127 is offline gto127  United States
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I looked at spec sheet on the regulator circuit & it's recomended a 1uf tantalum or a 10uf electrolytic(not sure why the large difference). The caps are used for stability of the regulator. the 47uf is in a timing ciruit in other part of machine. A 10uf electrolytic is still small so guess I'm in business.
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Old 1st May 2010, 01:25 AM   #8
amp_guy is offline amp_guy  United States
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You bring up a good point .
There seam to have been two reasons to use tant's

1. low leakage for timing uses.
there are other alternatives now.

2. small size.
Once again other alternatives now.

Bottom line better of due to their reputation and the high level of toxicity of tantalum, replace them all, (my advice )
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Old 1st May 2010, 02:55 AM   #9
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There's been a belief that tantalums have some magic low impedance property that's good for stabilizing regulators. Not true, but the esr does tend to fall in a narrow range, so the performance is very predictable. More so than aluminum electrolytics, and much higher than ceramic. Other than that, size is their only advantage- an advantage lost to modern aluminum electrolytics. I don't find much trouble with quality tantalums but would never design one into a new circuit. I don't have any problem replacing a bad one with another tantalum, and would examine the usage carefully before using a lower impedance aluminum electrolytic or ceramic. Remember they can't tolerate negative voltages. Installed backwards they usually short out and get hot. More annoying, if they don't short out, they become a noise generator. When I see a regulator with a noisy output, the first thing I look for is a defective or backwards tantalum.
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Old 8th May 2010, 06:18 PM   #10
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Actually there is a very good reason why tants are used, especially in regulator circuits - and that's because they have high ESRs. Usually in the 1-10 ohm range this extra resistance damps any resonance with the slightly inductive output impedance of the regulator. This is also the reason why very large values of capacitor are not usually used on the output of regulators. This resonance then moves into the audio band and reduces the available regulation rather than improving it as one might expect.
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