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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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2nd Sep 2022, 3:10 pm | #1 |
Pentode
Join Date: Apr 2011
Location: Bromley, Kent, UK.
Posts: 234
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Bi-polar electrolytic capacitors
Hi there, I’m working on a Sony pal decoder board from a professional piece of kit, and there are several surface mount bi-polar electrolytic capacitors used for signal coupling, which are in need of replacement (high ESR).
I’ve seen similar ones used in Panasonic Pro VHS models, and they are always a pain to source, especially surface mount types. In the past, I’ve used radials and sometimes the voltage rating has been quite a bit higher. CPC stock some of the values I need, but not all of them. I’m curious if anyone has experience of fitted non electrolytic capacitors instead, such as mlcc ? Though this may be trickier for some of the higher values. The values I’m looking for are: 10uf 16v 33uf 25v 47uf 6.3v 47uf 16v 100uf 6.3v Thanks |
2nd Sep 2022, 3:14 pm | #2 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
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Re: Bi-polar electrolytic capacitors
The dielectrics used in the very hich value ceramic capacitors have some nasty characteristics, not just large temperature coefficients. Microphony and non-linearity head the bill. They are also easily fractured in the larger physical surface mount packages both from board flexing and thermal shock from soldering/cooling. If you use them, look into the flexible-termination types for packages over 1206.
DAvid
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3rd Sep 2022, 8:15 am | #3 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 7,637
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Re: Bi-polar electrolytic capacitors
Hifi Collective sells a decent range of bi-polar caps - https://www.hificollective.co.uk/sea...r%20capacitors bit pricey but.
Andy.
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3rd Sep 2022, 1:36 pm | #4 | |
Pentode
Join Date: Apr 2011
Location: Bromley, Kent, UK.
Posts: 234
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Re: Bi-polar electrolytic capacitors
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3rd Sep 2022, 1:37 pm | #5 | |
Pentode
Join Date: Apr 2011
Location: Bromley, Kent, UK.
Posts: 234
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Re: Bi-polar electrolytic capacitors
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3rd Sep 2022, 1:56 pm | #6 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,706
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Re: Bi-polar electrolytic capacitors
Farnell seem to have plenty of non-polar (aka bi-polar) in radial through-hole types, https://uk.farnell.com/w/c/passive-c...st=non%20polar
Quite a lot of the surface-mount types are out of stock. David |
3rd Sep 2022, 2:12 pm | #7 |
Octode
Join Date: Mar 2016
Location: London, UK.
Posts: 1,046
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Re: Bi-polar electrolytic capacitors
If you have the physical space available and don't mind a bit of creative soldering origami, you can always put pairs of polar caps in series. If you consider this route, make sure to avail yourself to other points that give continuity with the SMD pads, i.e. nearby IC pins and the like, that you can anchor the caps to.
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6th Sep 2022, 4:37 pm | #8 |
Hexode
Join Date: Dec 2013
Location: Torrington, Devon UK.
Posts: 445
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Re: Bi-polar electrolytic capacitors
Unusual to see bI-polar smd electrolytics. Just had a look and Mouser seem to have all of them in stock.
Regards Graham |