Comments on: Beware when it comes to solder e-caps in PCBs

By: Gunnar Forsgren

Gunnar Forsgren — Wed, 07 Apr 2021 11:37:20 +0000

Japanese PCBs sometimes show the negative side of the electrolyte capacitor in THICKER size on the symbol on the PCB.
While western countries do the opposite.
Saw this on an ONKYO micro size stereo.

SO TAKE CARE TO DOUBLE CHECK and takes photos
of the PCB before you remove caps.

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By: Hermann

Hermann — Sun, 06 Dec 2015 13:06:38 +0000

What makes me go "DUH!" is the fact that on SMD tantalum caps, it's the other way round. The bar indicates the plus pole. I've not seen many tantalums in my repairs, however that makes this an even more dangerous trap, with my mind being used to e-caps.

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By: Robert Calk

Robert Calk — Wed, 25 Nov 2015 01:40:57 +0000

In reply to Gary Gemmell.

Yes, Paris has a great deal of knowledge and experience. I'm glad we have great guys like him helping us out!

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By: Robert Calk

Robert Calk — Wed, 25 Nov 2015 01:38:48 +0000

In reply to humberto.

I've put one in wrong on a breadboard before, but not soldered on a PCB wrong. I always double-check the placement of anything before I solder it. But I'm in no hurry. If I did it for a living and was in a hurry, I'm sure I would solder one in backwards at least once.

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By: Paris Azis

Paris Azis — Tue, 24 Nov 2015 16:10:19 +0000

In reply to Albert van Bemmelen.

Hi Albert

I agree with all you mention.
Bipolar caps do not need any similar diode protection, simply because they are not polarized.

Greetings

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By: Albert van Bemmelen

Albert van Bemmelen — Mon, 23 Nov 2015 23:19:49 +0000

In reply to Paris Azis.

Thanks Paris for your input. In the way you mentioned also many 3 pin regulators are protected to keep the voltage difference between the input and the regulated output within their maximum specs. And that's also the way how leds are protected when placed in higher AC voltage circuits.
Tantalum 'e-caps' are known to be most aggressive little chemical containers when they deteriorate. For instance in the well known great Tektronix Oscilloscopes when they eat copper layout from pcb's! But speaking about those bipolar e-caps I do wonder if they originally also are internally protected by diodes? (I think not?)

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By: humberto

humberto — Mon, 23 Nov 2015 17:10:56 +0000

In reply to mahin fofo.

Thanks mahin

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By: humberto

humberto — Mon, 23 Nov 2015 17:10:09 +0000

In reply to Robert Calk.

Yes Robert connecting an e-cap in backwards is a missfortune.

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By: humberto

humberto — Mon, 23 Nov 2015 16:57:13 +0000

In reply to Parasuraman S.

Yes Parasuraman, I think the best way of avoiding mistakes is marking at least one polarity on the PCB.

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By: humberto

humberto — Mon, 23 Nov 2015 16:41:32 +0000

In reply to Paris Azis.

Thanks Albert and Paris.

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