Replacing tantalum caps, advice needed

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Replacing tantalum caps, advice needed

Postby wez » Sat Oct 08, 2016 3:50 pm

So after smoking a tantalum cap on one of my MCI JH-110 machines in a big way (explosion AND fire, brilliant) I'm wondering if I should replace them with something less volatile. They're not in the audio path, but hanging off the input and output of an LM309 regulator in the transport section.

I'm doing my research but would love some advice - can I use an electro or ceramic cap here? Is ESR the (only) issue? Value is 15uF 40V.

Big thanks to the brains trust in advance!
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Re: Replacing tantalum caps, advice needed

Postby rob » Tue Oct 11, 2016 8:28 am

When tanatalums fail, usually they fail as a dead short
If they are hanging across a power rail the results can be impressive.

sometimes it is important to keep tantalums in place as a type. And so replacing like with like is always a good rule. Modern tantalums are much more reliable .... well at this point in their history this seems to be the case.

however with regard to decoupling caps around a regulator IC in a linear supply I wouldn't see an issue with using electrolytic caps of the same value. I would definitely use low ESR 105deg caps. WES sell a series called EXR ... these are good.
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Re: Replacing tantalum caps, advice needed

Postby chrisp » Tue Oct 11, 2016 4:09 pm

What he said ^^^^^^^^^^^^^^^^^^^

In audio paths, it can be more critical to use like for like, although I have seen tants replaced by an equivalent value electro in parallel with a small 100pf mono cap to more closely mimic the impedance of a tant cap. Trouble with electros is they don't last as well as the others do (although they tend to fail to a break rather than a short, so less in the way of fireworks!)
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Re: Replacing tantalum caps, advice needed

Postby wez » Wed Oct 12, 2016 12:49 pm

Hey thanks Rob & Chris, much appreciated.

I managed to source some 22uF 35V Vishay tantalums, but at $6 each (and coming from the UK) I might give those recommended electro's a go next time!

Big thanks again!
Last edited by wez on Wed Oct 12, 2016 4:43 pm, edited 1 time in total.
wez prictor
composure music
http://www.composuremusic.com.au/

Australian importer of Crumar Mojo keyboards & accessories. Vintage keyboard fetishist.
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Re: Replacing tantalum caps, advice needed

Postby rob » Wed Oct 12, 2016 3:37 pm

*** eek !
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