This morning I received two KEF C30 speakers for free. I transported them home on the back of my bike, individually covered in a blanket and then tied together. When I got home one of the two speakers produced beautiful sound, the other only produced almost inaubibly soft high sound. I changed the cables and that proved the problem to be in the speaker.
Specs of the Kef C30 speaker:
KEF C30 - Manual - Two Way Stand Mounting Loudspeaker System - HiFi Engine
I decided to open the faulty speaker to see if I could find any damage of the transport by bike and I took some resistance measurements of different parts of the electronics.
However my knowledge of electronics is limited to what I learned in secondary school physics and how a cross-over exactly works is a complete mystery to me. So I need some help with investigating what the defect in this speaker is.
Description of situation when I opened the speaker:
Woofer (see info in attached pictures) was attached with a red and a purple cable. Red cable was attached to the connector on the driver marked with red dot.
Tweeter was attached with purple and blue cable. Blue cable was attached to tweeter-connector with red dot.
I disconnected the woofer and the tweeter to do the measurements. I did not remove the cross-over from the back of the speakerbox. As far as I can see without removing the cross-over I do not see any sign of over-heating damage or any broken solder or loose cables.
Resistance measurements:
Red binding post on outside red to red woofer cable: 1,0 ohm
Red binding post on outside red to purple woofer cable: infinite
Black binding post on outside red to red woofer cable: infinite
Black binding post on outside red to purple woofer cable: 0.6 ohm
Red binding post on outside red to blue tweeter cable: infinite
Red binding post on outside red to brown tweeter cable: infinite
Black binding post on outside red to blue tweeter cable: 0.6 ohm
Black binding post on outside red to brown tweeter cable: infinite
Between both connectors on woofer: infinite
Between both connectors on tweeter: 6,7 ohm
The conclusion I draw from these observations is that the woofer is probably broken (because of it's infinite resistance).
Can any of you shine any more light on my findings? Or maybe you have instructions for what more I should measure/investigate.
I did not dare to test the woofer or the tweeter in the other, still working, speaker, because I'm afraid that I could damage the undamaged electronics of the working speaker by introducing a faulty woofer/tweeter to it. Is this a true risk?
I'm looking in to this because I love to learn new things and also I hope to be able to repair/replace the broken part even if it costs some time/money.
Thanks in advance.