Below is the schematic for my motorola (hope it shows up, I didn't clip it very well)- I'm replacing the 5 mfd cardboard electrolytic in the crossover circuit with a polarized 10 mfd 50 v electrolytic. The problem is I can't tell from the schematic exactly which way to wire them in. The other electrolytics in the schematic seem to indicate polarity, but here the symbol is just two straight parallel lines. I'm guessing that the hot end is coming from the E1 speaker (top right of schematic, middle speaker) and negative to the E2, but I'm not sure. I'm still learning and do most things "paint by number" as they say, but I got stumped here. Thanks for your help : )

AFAIK, audio crossover caps have to be non-polarized.

Bob

Connect two 10mfd back to back to repl the NP cap...

Actually, I think you want to connect the two caps is series. Maybe that's what you meant by back-to-back?



Rich

You'll note the little "NP" below the capacitor symbol. This, and the schematic symbol (without a + and -) means the capacitor is a non-polarized electrolytic. An ordinary (polarized) electrolytic will not work properly here.

You can buy new non-polarized caps, or you can make one by connecting two ordinary capacitors in series back-to-back (both + terminals connected together, or both - terminals connected together) as 35Z5 suggests. Connecting capacitors in series reduces the overall capacity, so you have to start out with bigger capacitors. In this case, two 10-uF capacitors in series will give you 5-uF. Each should have a voltage rating equal to, or greater than that of the original cap.

Another way around this is to use a metalized polyproylene capacitor of the same ratings as the original. Since metalized film caps are inherently non-polarized, you get away from the whole issue. They also tend to do a better job of passing high frequencies, which may make the radio sound better.

What 35Z5 said is exactly correct:

He needs a 5uf non polar... so he'll need to connect two 10uf polarized caps back to back. neg to neg or pos to pos.

"BACK to BACK" means ... neg to neg -or- Pos to Pos

That way you'll create a non-polarized cap of 1/2 the value.... same voltage rating.

"In series" ... means pos to neg ..... then you STILL have a polarized cap... of 1/2 the value but double the voltage rating.

I could interpret this to mean "connected in parallel, " with the neg of one connected to the positive of the other. I spent a lot of years in the semiconductor business. Back-to-back connection of SCRs was always in parallel, one going in each direction to make a complete AC switch.



Rich

I took back-to-back to mean caps in series, with polarities reversed (+ to +, or - to -). But I can understand the confusion. That's why we have pictures:



Or just screw it, and buy the the non-polar (sometimes referred to as "bi-polar") caps:

http://www.mouser.com/ProductDetail/Nichicon/UVP1J4R7MED/?qs=3Xh8WsvUCBFkPc4AV9a6Da7ijxsyj1ErAFWcmr0KKbM%3d

http://www.mouser.com/ProductDetail/Lelon/RN4R7K1HBK-0511P/?qs=Xsd3MJs19V9npTCsgaLk2GEPtC5mHkmYfGo5pkjzSQY%3d

or film caps, which aren't polarized to start with:

http://www.mouser.com/ProductDetail/Panasonic-Electronic-Components/ECQ-E2475KF/?qs=3ERjQB%2fgCVI47dyK2FaEot%2f7y%2fassRa%2f3gDPSdmHux8%3d

Note they are all 4.7uf, instead of 5uf. Most of the time its close enough. Note its a 10% tolerance, so 4.7 could be anywhere between 4.2 to 5.2uf.

Okay, thanks for the info! I saw the "NP" and thought it meant "non-polarized", but didn't realize that this nixed the polarized caps completely. Will look into getting some non-polarized caps, and now I know for the future. Looking forward to hearing this console with all six "golden voices" firing up at the same time....