In article , Bob Urz wrote:


GregS wrote:

In article , wrote:

I had a customer bring in an Infinity KPX00 crossover for a 6.5" car
unit. Coil L2 has burnt marks on it, Its a 24db linkquitz riley filter
(or so the spec sheet says).
Customer claims low tweeter output

http://manuals.harman.com/INF/CAR/Owner's%20Manual/KAPPA%20PERFECT%206-1%20om
.p
df

in:
(+)
-------|
|
== C=15.7ufd
| C=14ufd R=(1,2,4) OUTPUT
|------------][------------/\/\/\/\/\------|
|
L2 (burnt) |
*
(tweeter)
| *
| |
------------------------------------------------
(-) (-)

So, the input is a series cap inductor combination with a 15.7 MFD and
unknown coil in series with the amp. The center tap of the two feeds a
14MFD cap and then goes through a series resistor adjustable pad
to the tweeter. I tried to read the coil on my sencore, and it measures
about .3 MH. It won't pass any ring test (air core) so i know turns are
shorted and this value is suspect. Any clue on the value of this coil?

Strange, this seems to be a 3rd order filter rather than what the tear
sheets says.
Only one coil on the high pass with two caps.
Minus the pad, it looks like the 3rd order 18 DB filter he

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

and these calculated 3500hz values are (4 ohm nominal)
C=7.5 ufd
L=0.1364 mh
C2=22.7

standard replacement coil values are .1,.13,.15,.20,.27,.33 and etc.

Thoughts?

Bob


Plugging in the values, I seem to get slightly higher values of L1.
but not much. A crossover cannot be tested by itself. The
drivers also play into the crossover, also making poles and things.
I would try some real time values and listening test. the value should be
between .3 and .5 mh. If you could measure the R, unwind the coil,
and measure R, that might tell the extent of the damage.

greg
The link i provided was found with a quick search.
I am guessing its that topology.
Some of the information seems to be conflicting.


What do you mean by measure R with the coil wound and unwound?

Bob

Unwinding removes the short. You may actually see where the short is, ir
may be welded together.

grge