capacitor polarity markings

[GregDunn]

So weird to be posting in the Beginners thread, but I learn something every time I repair equipment, so I guess is some respect I'm still a beginner with every new piece of gear I work on...

I've been installing and replacing capacitors for literally decades.  The problem is that now caps are starting to come in packages which are unfamiliar to me.  I've seen almost every kind I can think of - big aluminum cans, tantalum cans, gumdrops, axials, radials, etc. etc. and usually polarity is obvious - but my latest Digi-Key order came with these and I want to check and make sure I've decoded them right.  I would expect the tapered end to be the + and the banded end to be the -, right? 

The only reasons I'm confused are that the data sheet shows both this package and the conventional aluminum can side by side, and they're depicted such that the negative end of the can is alongside the tapered end of the other one.  There are no legends indicating polarity for this particular package anywhere on the data sheet.  Also, a quick google for aluminum electrolytics came back with images showing some with stripes indicating + and some with stripes indicating - !!! 

I'm sure there's actually a standard and that some of these pictures are just wrong - does someone have a copy of the standard or a clear description of how to interpret this particular package?  This one is a D-K part 4201PHCT-ND if anyone cares.

[Old Printer]

I absolutely belong here in the beginner section so please take this with a grain of salt. Most of the polarized capacitors I have seen in the last couple years mark the negetive lead. Since this cap has a band on one end I would "guess" that to be the negetive lead. I would not be comfortable enough with my guess to install it that way so I would be looking for an answer myself. Curious to see how this plays out. Thanks for putting it here.

[fpliuzzi]

Figure 2 of the attached data sheet depicts the tapered end as being positive. Hope this helps.

[GregDunn]

Figure 2 of the attached data sheet depicts the tapered end as being positive. Hope this helps.

How did I miss that little + sign?  Yes, that's clearly it.

[fpliuzzi]

Figure 2 of the attached data sheet depicts the tapered end as being positive. Hope this helps.

How did I miss that little + sign?  Yes, that's clearly it.

That + sign in the data sheet is pretty puny. I had to enlarge the pdf on my small laptop screen to see it clearly.

[JS]

My guess would been the stripe on the negative, pretty standard.

But yes, they could make the datasheet more clear about that, I guess a little more black ink on the sign would be too expensive.

JS

[GregDunn]

Apparently some capacitors (SMD and some of the smaller, square packages) really do have the stripe on the (+) end, which was part of what confused me.  Look on this page under "polarity":

https://en.wikipedia.org/wiki/Electrolytic_capacitor

[vk6zgo]

So weird to be posting in the Beginners thread, but I learn something every time I repair equipment, so I guess is some respect I'm still a beginner with every new piece of gear I work on...

I've been installing and replacing capacitors for literally decades.  The problem is that now caps are starting to come in packages which are unfamiliar to me.  I've seen almost every kind I can think of - big aluminum cans, tantalum cans, gumdrops, axials, radials, etc. etc. and usually polarity is obvious - but my latest Digi-Key order came with these and I want to check and make sure I've decoded them right.  I would expect the tapered end to be the + and the banded end to be the -, right? 

The only reasons I'm confused are that the data sheet shows both this package and the conventional aluminum can side by side, and they're depicted such that the negative end of the can is alongside the tapered end of the other one.  There are no legends indicating polarity for this particular package anywhere on the data sheet.  Also, a quick google for aluminum electrolytics came back with images showing some with stripes indicating + and some with stripes indicating - !!! 

I'm sure there's actually a standard and that some of these pictures are just wrong - does someone have a copy of the standard or a clear description of how to interpret this particular package?  This one is a D-K part 4201PHCT-ND if anyone cares.

Interestingly, that package is not a new style----I first saw it used in a Gates/Harris Modulation Monitor in the late 1970s.
I never saw it anywhere else till now------I had started to think I imagined it!

[Terry01]

Give it a quick test with your DMM in resistance mode. If it's the wrong way around it'll give you a negative measure. The correct way around will give you a positive measure.