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how to replace crossover cap (1 Viewer)

Will.MA

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Oct 23, 2004
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After noticing that the high-end was missing in a pair of bookshelves I picked up used and had stored until now, I discovered that the tweeter hasn't failed but instead the capacitor wire is severed. One end of the cap is soldered to a lead that connects to the binding post, and the other end of the cap is soldered to a lead that connects to the tweeter's terminal. The circuit is broken on the part of the cap that looks like soldering flux. Literally it is sliced in two parts. How do I know what size cap to use for replacement w/o sending it to Polk? I don't want to pay the manufacturer an exhorbant cost for a simple repair that I can do myself. The system is Polk Audio R10.

Thanks, WMA
 

PaulT

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Oct 28, 2002
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You could email Polk and they may reply what the value of the cap is, or you could take the other speaker apart, desolder the good cap and measure it with a capacitance meter.
 

Will.MA

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Oct 23, 2004
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I took the drivers out of the cabinet to get a good look at the cap. It has the following markings covering it:

T.I. (maybe Texas Instruments)
4 MFD
50 V
+/- 5%

Are these values that I can reference to replace the damaged cap?
 

Andrew Pratt

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Dec 8, 1998
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I'd replace both caps on each speaker just to make sure things remain even. This or this cap should do what you need I believe. I used Solen caps in my cross overs and given the minimal cost I'd likely suggest them over the Dayton's but either should work fine.
 

PaulT

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Messages
932


You bet
4 microfarad, 50VDC, tolerance is 5%. You are not really worried about the 50V value in this case. Either of the caps suggested by Andrew should work.

I also agree that if you change both speakers caps at the same time, then the crossovers should be fairly well matched again.
 

Brian Fellmeth

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Jul 30, 2000
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789
If you are going to solder directly onto the tweeter terminal, be careful- the voice coil can't tolerate much heat. You might was to check if your local radioshack has 4 mfd poly caps- that will work fine too, but don't use one with plus or minus marked on the leads. Also, I wouldn't bother to replace the other speaker unlesss you hear a difference after fixing the bad one. It is probably unnecessary and there is risk of creating a leaky cabinet or damaging a driver.
 

Will.MA

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Joined
Oct 23, 2004
Messages
98


What function does the other cap serve? Does it prevent low frequency signals from passing to the woofer?

I am replacing the cap because one of the leads is severed, not because it has failed. I can get program playback from the woofer. That means the other capacitor is okay, right?

Thanks for all of your insights into a solution for my problem. It is appreciated.
 

Andrew Pratt

Senior HTF Member
Joined
Dec 8, 1998
Messages
3,806
I meant replace the corresponding cap on the other speaker not the one on the woofer crossover.
 

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