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Help identifying tantalum capacitor

That is what I would take it to be.

I might be tempted to assume it is across the 5 Volt supply and do a quick check with the multimeter to the VCC and GND pins of a nearby TTL IC I can see.

Dave
 
Go with tant to replace tantalum--electrolytics have a somewhat different reactance vs. frequency characteristic and my not work in this application. Added to that, tants are pretty much are ±20% tolerance (you can get tighter tolerances) vs. electrolytics, which are basically ±50%.
 
Also, as well as sticking to a Tant cap, get one with the same uF value AND voltage rating. Over the range of 10V, 15V, 25V and 35V Tant capacitors, the ESR gets higher with each step. I once had a case where a linear regulator was stable with 15V tants on its inputs & outputs, but oscillated with 35V units of the same capacitance for this reason.
 
Hugo Holden said:
Also, as well as sticking to a Tant cap, get one with the same uF value AND voltage rating. Over the range of 10V, 15V, 25V and 35V Tant capacitors, the ESR gets higher with each step. I once had a case where a linear regulator was stable with 15V tants on its inputs & outputs, but oscillated with 35V units of the same capacitance for this reason.
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If the aim is to increase reliability by increasing the voltage rating, use smaller capacitors with higher voltages in parallel.
For two identical capacitors in parallel the ESR will be halved, and the capacitance will be doubled. The reality is the the nominal capacitance will be slightly reduced (two parallel 4.7uF is 9.2uF instead of 10, two 10uF will be 20uF instead of 22uF), but given the wide tolerance of polarised capacitors anyway it's unlikely to make much difference.

On the other hand - good luck getting two pairs of capacitor leads into the same PCB holes, or piggybacking a second capacitor onto the leads of the first. (longer leads = theoretically more inductance).
 
Lololobolosse said:
Hello, i need help to confirm this tantalum capacitor is correctly a 10uf 15v
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Maybe it's just me, but I would read it the other way around. Why? Because tantalum caps have voltage ratings of 6.3, 10, 16, 25, 35. A rating of 15V would be very unusual. To me, it's 10V with 15μF.
 
Tantalum capacitors need higher voltage rating than first used. Somewhere on the WWW there's more than one report about how they degrade over time to where the difference between voltage rating and failure voltage decreases. Be it due to failure of package seal or internal chip changes I don't know. But I replace old ones with higher voltage ratings when changing them out. I also am of the mind that if it ain't broke, don't fix it. This it more true if the person doing the change out has little to no soldering experience. Damage to the PCB from poor soldering ability out weights the often touted hotgun technique of replacing all tantalum caps as a troubleshooting technique, IMHO.
 
DeltaDon said:
Tantalum capacitors need higher voltage rating than first used.
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That is nonsense.

DeltaDon said:
Somewhere on the WWW
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Highly accurate source. :giggle:

While you *can* always use a cap with a higher voltage rating, you should not unless you have no other choice. Because otherwise, what started as e.g. a 6.3v one will end up being replaced with a 50v one and then you run into issues. ESR and other characteristics are different between voltage ratings and at some point are too different to the original cap (like between a 6.3v and a 50v one).

Especially if you have not much knowledge, you should use exactly the same part. If you gain some knowledge, you can fix issues by making sure all caps are two steps higher than the working voltage, so when you are dealing with 5v, caps should have a rating of 10v (not 6.3v).
 
That gives a very good description of T caps. The upshot is....if T caps have voltage applied frequently, any deterioration of the dielectric is healed. However, if they sit for a long time with no voltage applied, the dielectric fault becomes too large and the current thru that fault upon application of a voltage becomes so large that the heat generated literally explodes the cap. The result is either a short or open... if you are lucky. Ask me how I know...........
 
Given that this tant appears to be paralleled with a small ceramic (you can check with a continuity test), it's probably a decoupling cap and ratings aren't terribly critical, so this discussion may be a bit academic.

This isn't the first time that the question's been asked, btw:

Identifying parts for a Compaq Portable 1 - Page 1

Identifying parts for a Compaq Portable 1 - Page 1
www.eevblog.com

I'd probably try to find a Sams Computerfact chart for your machine (or a similar one) and see what the BOM says.
 
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Good Lord, it is not Rocket Science.

Look up the BOM......might be lucky to find that for a vintage machine. You have to use your common sense.... mostly The markings are crystal clear.

Assuming the original capacitor is not shorted out, if you are confused for some oddball reason about the notion whether it is a 10uF 15V or a 15uF 10v (the latter is highly unlikely, every vintage Tant cap I have ever seen, on its label specifies the capacitance first and the voltage second, and if somebody can find one that reverses this order I would love to see it) simply remove the capacitor and check it with a capacitance meter.

And, obviously, you should not be replacing it in the first place, unless you have determined it is defective. Which, in the case of a tantalum cap, means it has shorted out or gone to a low leakage resistance. Dead easy to check if you lift just one of its legs for testing.
 
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Hugo Holden said:
Good Lord, it is not Rocket Science.
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To be fair, each user of this website has a different spectrum of knowledge/experience. For example, I imagine that for some readers, the concept of a 'resistor' is only something recently learned.

( However, with that said, there have been many times when I have not replied to a post because I know that the answer is easily found online. )
 
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