[beat]

Hey guys,
I have a pair of old polk monitors I was giving to the lil sister to find that one of the tweeters quit working. I assumed a shot voice coil so I dug up another vintage pair...well, after troubleshooting a while I find the crossover is to blame. I suspect the big cap in there and I would just replace it since it is old anyway but I cant find any specs written on it. Is it possible to use my multimeter to find the value of it? The only markings say e-0012-1 and 12j 100v. Just to confirm, they are 3 way and there are 3 caps..the tweeter cap will be the largest of them right?

thanks, beat

[ctviggen]

I'll guess 2,400uF (microfarad) or 2.4 millifarad.  I used E = (C V^2)/2, so that E = 12 joules, C is the unknown capacitance, V  is 100 Volts.  That's quite a large cap, so large that it can't be correct! 

[BradJudy]

Is it possible to use my multimeter to find the value of it?

Does your multimeter measure capacitance?  Most cheap ones don't, but a lot of DMM's do.  Unfortunately, many of them have a limited range on capacitance and can't measure beyond 200uF or so. 

Edit: Naturally, you'd have to measure the good one from the other speaker, not the blown one. 

[beat]

Thanks guys,
my meter measures between 20 micro (that is the upside down h right?) and 2 nanofarads (lowercase n?). I cant get any sort of reading at all even with new caps I have laying around. 

[ctviggen]

Is there just the capacitor between the input and the driver?  If so, you could use the following and guesstimate the value:

http://www.apicsllc.com/apics/Misc/filter2.html

Basically, you'd need to guess the crossover frequency and the impedance.  You could get a good estimate of the crossover frequency if you had test tones and used the good speaker. 

[ctviggen]

For instance, using 4 ohms nominal impedance and 5,000 Hz crossover point for a first-order crossover, the capacitance would be around 8 uF (microfarad). 

[vman71]

Beat,

If you need somebody to fix your xover for you, drop me an email.

Mike
mvansloten@gmail.com

[dangerbird]

Hey guys,
I have a pair of old polk monitors I was giving to the lil sister to find that one of the tweeters quit working. I assumed a shot voice coil so I dug up another vintage pair...well, after troubleshooting a while I find the crossover is to blame. I suspect the big cap in there and I would just replace it since it is old anyway but I cant find any specs written on it. Is it possible to use my multimeter to find the value of it? The only markings say e-0012-1 and 12j 100v. Just to confirm, they are 3 way and there are 3 caps..the tweeter cap will be the largest of them right?

thanks, beat

 What model ?

[Rick Craig]

Hey guys,
I have a pair of old polk monitors I was giving to the lil sister to find that one of the tweeters quit working. I assumed a shot voice coil so I dug up another vintage pair...well, after troubleshooting a while I find the crossover is to blame. I suspect the big cap in there and I would just replace it since it is old anyway but I cant find any specs written on it. Is it possible to use my multimeter to find the value of it? The only markings say e-0012-1 and 12j 100v. Just to confirm, they are 3 way and there are 3 caps..the tweeter cap will be the largest of them right?

thanks, beat

It's probably not a capacitor but a polyswitch that needs to be replaced.

[pecker]

Did you try here:
http://www.polkaudio.com/forums/showthread.php?t=38755

[ctviggen]

Woah!  That's a nice site. 

[beat]

Hey thanks guys,
They are monitor 10s....I believe the original release before the sl3000 tweeter. Thanks for the link to the schematics I think I can get it from there. I still wonder though why my meter wont measure the caps at all. Are you supposed to just place the black and red leads to both sides of the cap and hold them there? does the cap need to be charged first or something?

thanks again, Beat

[dangerbird]

If you have ruled out the tweeter,then most likely it's the polyswitch(tweeter protection),if you e-mail polk, they will send you a pair for the asking. As the poly's age,they are easily tripped,which is most likely your problem. It's a relatively simple procedure and you might as well change both since you are in the neighborhood. Good luck.

[beat]

If you have ruled out the tweeter,then most likely it's the polyswitch(tweeter protection),if you e-mail polk, they will send you a pair for the asking. As the poly's age,they are easily tripped,which is most likely your problem. It's a relatively simple procedure and you might as well change both since you are in the neighborhood. Good luck.

Thanks DB, I will look into that.

[beat]

DAmmit!!

stupid!! yeah it was just the protection..should have checked it first. What threw me was that the bottom end was working fine. I figured if the protection blew it would kill the whole circuit and not just part. I assomed..I made an ass o me.

thanks and sorry to trouble y'all.
Beat

[dorokusai]

Great post Dangerbird! 

Beat - I can't hear you yet, turn it up 

Mark