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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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2nd Jul 2022, 11:21 am | #1 |
Tetrode
Join Date: Jan 2020
Location: Ilkley, West Yorkshire, UK.
Posts: 92
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What's the polarity of this cap?
I removed a capacitor from the board to replace it and by Murphy's law I dropped it before I checked the polarity and it is the one cap that isn't marked with polarity either on the board or on the schematic! Maybe it is non-polar?
I'm attaching the part of the circuit which shows both ends going to around 9v - maybe someone can interpret this better than I can? |
2nd Jul 2022, 11:22 am | #2 |
Tetrode
Join Date: Jan 2020
Location: Ilkley, West Yorkshire, UK.
Posts: 92
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Re: What's the polarity of this cap?
Oh, I forgot to say, it is C7.
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2nd Jul 2022, 11:30 am | #3 |
Octode
Join Date: Dec 2018
Location: Llandeilo, West Wales, UK.
Posts: 1,092
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Re: What's the polarity of this cap?
Hazard a guess that it is an electrolytic bi-polar cap. Marked as 2.2uF 25 volt working. So either way round.
The other electrolytics you can see (C6, C33 and C34) are clearly designated with a + sign for their positive end.
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2nd Jul 2022, 11:33 am | #4 |
Dekatron
Join Date: Jul 2008
Location: Charmouth, Dorset, UK.
Posts: 3,601
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Re: What's the polarity of this cap?
If they are PNP transistors the negative would go to the 9.1v rail.
Peter You just beat me Snowman, yes there is only 0.1 of a volt across it anyway. |
2nd Jul 2022, 11:34 am | #5 |
Octode
Join Date: Jul 2009
Location: Carmel, Llannerchymedd, Anglesey, UK.
Posts: 1,498
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Re: What's the polarity of this cap?
Frome the partial diagram, it looks as though the top is probably slightly more positive than below. What was the type of cap you removed?
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2nd Jul 2022, 3:32 pm | #6 |
Tetrode
Join Date: Jan 2020
Location: Ilkley, West Yorkshire, UK.
Posts: 92
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Re: What's the polarity of this cap?
Thanks all. I had binned the capacitor but I dug it out and it said NP on it. So I tested it and as it seemed ok, re-used it.
Many thanks - it's the first time I've come across a nonpolar capacitor! Having replaced all the other electrolytics in this Pioneer quad decoder, maybe it will now work ok. |
3rd Jul 2022, 9:04 am | #7 |
Dekatron
Join Date: Jul 2008
Location: Charmouth, Dorset, UK.
Posts: 3,601
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Re: What's the polarity of this cap?
They are quite a modern invention - by my standards.
Peter |
3rd Jul 2022, 10:39 am | #8 |
Octode
Join Date: Dec 2018
Location: Llandeilo, West Wales, UK.
Posts: 1,092
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Re: What's the polarity of this cap?
If you do decide to replace it (might be a good idea) then a modern 2.2uF 63 volt poly cap will out live the tuner. Just an example https://uk.farnell.com/vishay/mkt181...oss_price=true
It will not care which way round it is fitted. You might find them cheaper on eBay.
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