KLF-30 crossover problem (no mid-range)

[masterxela]

One of the mid-range horns went silent on me, I pulled off the crossover, and the 22 ohm resistor in the white ceramic case had fallen clean off. (This after pushing them very hard for hours, then moving them. The solder melted?!..............)

I re-soldered it in place... horn is still silent.

Suggestions? Possible to send it to someone? Possible to replace?

Is there a circuit diagram available? I've had some EE courses recently

Thanks,

Alex

[Southern]

If you have a meter measure the resistance of the resistor that you soldered back on. Also measure the resistance of the midrange driver. If you don't have a meter then swap the midrange driver from the working speaker to see if the problem is with the crossover or midrange driver.

Here is a link to crossover schematics: http://forums.klipsch.com/forums/t/130178.aspx

[masterxela]

23 ohms

1.7 ohms (while still wired to the crossover)

Thanks for the schematic

[Southern]

Measure the restance of the midrange with it disconnected from the crossover. I believe that you were reading the resistance of the inductor.

[WMcD]

Shame on you for overdriving that poor unit. Smile. To make up for this you are obligated to take pictures of your autopsy. That is just to build our knowledge base here. Seriously.

You might realize the following. When you measure resitance acoss the midrange terminals you are actually measuring the parallel resistance of the voice coil of the mid , the inductor which is wired across the voice coil, and the secondary windings of the autotransformer which is also wired across the voice coil. It is difficult to tell but any two of the three could be burned out.

So I say:

Take apart the wiring. At least to make sure that all the current coming from the ohm meter is going across the device under test and not something connected to it.

Using the ohm meter:

Test the resistor to confirm resistance.

Test the autotransformer .This should be done from 5 to 0, 3 to 0 and 5 to 3. All of these should be somewhat less than 10 ohms d.c. and probably less than 2 ohms. If one of these tests show open, you've fried the autotransformer.

Test across the inductor. This too should be less than 2 ohms or so.

The overall problem may be that you've fried the voice coil. That somewhat high reading could show a fault. Voice coils usually are lower around 4 - 10 ohms. And if burned out, they are usually infinite. Occasionally the windings are melted in such a way that you get something higher like the 23 you're seeing.

On old classic ohm meters, here is enough current to make a clicking noise from the driver. Newer ones, maybe not. So you could try tickling it with a 1.5 ohm battery and see if you get a click and scratching noise. That would be a good sign.

If it is silent, you've got a partially burned out voice coil.

If so, call 1800KLIPSCH and see if they have a replacement voice coil assembly. If is like some other units of the era, it is relatively simple to make the mechanical and electrical swap.About $40.

Again, and in all seriousness. Please take pictures and post the process of changing out the voice coil.

WMcD

[masterxela]

Got the entire thing taken apart and started poking around w/ my multimeter - didn't have a good connection when I re-soldered the resistor. All better

Don't think I'm gonna put the crossover back in there though...

[Mighty Favog]

Bob Crites can build you a pair that are better than whats in there. I've got a pair in my 20's.

[masterxela]

Estimate for $$, and time without tunes?

[Mighty Favog]

What they look like:

http://critesspeakers.com/crossovers.html

(Those are my 20's on there, I have the first pair.)

How much they cost:

http://critesspeakers.com/prices_-_new_crossovers.html

Turn around? Send Bob and E-mail.