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Discussion Starter · #1 ·
I picked up some speakers cheap. The kid that had them blew them up. I mainly want the cabinets, but may think about replacing the damaged parts. the tweeters are done, for sure.

Right now I am wondering how to test the tweeter section of the passive cross over with a volt meter.
 

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Discussion Starter · #2 ·
Turns out that one peek is worth a thousand test.

The resistor (I have it lifted up in the picture) is badly burned. It's cracked along it's entire length. One wire was burned through. That black stuff is thoroughly cooked hot glue, or whatever they used to stick the parts to the board.

Electrical network Circuit component Resistor Wire Optoelectronics
 

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Elite Shackster , HTS Moderator Emeritus
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Yikes. I've never seen a resistor used as a fuse :)

That looks like the inside of one of my power strips at work after a lighning storm. When we cracked the case it was all charred and you could see several components burned/exploded.

Resistors are easy enough to replace, I'd give it a whirl and see if the speakers are worth saving.
 

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Discussion Starter · #4 ·
I think I'll try and fix it. The yellow cap next to the resistor is also toast. The rest of it seems OK.

I found out the OEM woofers and tweeters are available. I would need 1 woofer and 2 tweeters. It may make sense to use them with their crossovers rather than replace the speakers with another brand.
 

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Hi Joorge,
The yellow ones are probably multilayer polyester film capacitors and are typically a higher voltage rating & are better for high frequencies. However they are larger than electrolytics for the same value.
Electrolytics as their name implies are fluid filled.
This is straight from wiki:- http://en.wikipedia.org/wiki/Capacitor
An electrolytic capacitor is a type of capacitor that uses an ionic conducting liquid as one of its plates with a larger capacitance per unit volume than other types
 

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Probably because thay couldn't get a reasonably sized yellow one or to save costs.
The electrolytics are a lot smaller & cheaper for the same value but they tend to fail earlier. Normal lifespan of an electrolytic is 10 - 15 years.
 

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Discussion Starter · #12 ·
PE wants $7. It was only $5.75 for both of the other ones. I see why they used the electrolytic cap. I think I will keep looking.

I tested the old cap and it was 27.25uf. That's about 10% over the stated 25uf on the label. Maybe it will be OK for awhile.

What would happen if I used a 22uf? They are readily available for less than a dollar.
 

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Caps have a 5-10% tolerance on marked values, depending how much they cost, but you can always get very close by paralleling caps of similar design and voltage rating. I'd use a 22 + 3 uf to replace the 25uf, or build with the 22 and see if you need the 3uf; it's easy enough to add. We're still talking single digit expenses...
Frank
 
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