Bi-Polar Capacitor Confirmation (please)

jetusenet

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Hi;
I'm working on an Aztarac PCB and came across an electrolytic cap that had appeared to have the negative stripe installed into the positive pad. Upon closer examination it looks like a bi-polar cap but I would feel much more comfortable if I could get some confirmations on my hypothesis........

It was pulled from location C4 on the CPU/Sound PCB, if that helps.


Thanks much
Jeff
 

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Looks normal to me. Bi-Polar caps are usually labeled "BP" or "NP" somewhere on them. That and there's clearly a negative symbol on the cap.
 
I attached another picture of a capacitor that there is no doubt with regards to the polarity. Notice the "arrow" which runs in one direction only.

With the one in question, it seems to be indicating "either way".

I am not too sure that the symbol on the cap in question is actually a negative symbol, it looks a little different, almost like a - no parking sign, you know what I mean, a "P" with a line through it........

Jeff
 

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Last edited:
That is definitely a polarized electrolytic and the marking is on the negative lead... as everyone else has said. Now...

On your Aztarac, C4 is used as an input coupling cap for the power amplifier.

Rule of thumb:
For coupling caps... positive lead to signal source and negative to amplifier.
(it will work either way!)(Aztarac shows it that way and datasheet for MB3730A shows it the other way)
For circuit boards... if it works correctly don't mess with it. (especially if it is 25+ years old)

My 2 cents worth.

Kenneth
 
Thanks guy for all the help, talking me down etc.....
I have the schems and will be verifiying polarity tonight.
Peace
Jeff
 
I have seen bipolar caps marked with the negative stripe but it will have NP or BP on it.
On the second pic you can see the arrow that points to the negative side. Also, on axial caps one side will have a rubber seal which is always the positive. If you see a rubber seal on both sides it might be a bipolar but not always.
 
It LIVES!

Great news - I fired it up and got game!!!!!!

I installed the cap with the positive towards the IC (as per the manufacturer specs) and all is well.........

Now I am onto the CP fabrication...........
 
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