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Old 2nd Jul 2022, 11:21 am   #1
jmcilkley
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Default 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?
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Old 2nd Jul 2022, 11:22 am   #2
jmcilkley
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Default Re: What's the polarity of this cap?

Oh, I forgot to say, it is C7.
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Old 2nd Jul 2022, 11:30 am   #3
snowman_al
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Default 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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Old 2nd Jul 2022, 11:33 am   #4
Peter.N.
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Default 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.
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Old 2nd Jul 2022, 11:34 am   #5
lesmw0sec
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Default 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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Old 2nd Jul 2022, 3:32 pm   #6
jmcilkley
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Default 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.
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Old 3rd Jul 2022, 9:04 am   #7
Peter.N.
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Default Re: What's the polarity of this cap?

They are quite a modern invention - by my standards.

Peter
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Old 3rd Jul 2022, 10:39 am   #8
snowman_al
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Default 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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