Hi. I'm new to this forum. I'm from Germany, so bear with me and my humble and clumsy english. I love JBL speakers for their excellent sound and design and loved them already in the sixties and sixties.
Now I collect these speakers and use them in bass and organ amplifier equipment and such.
From time to time I buy a speaker and even succeeded in repairing some. My first reconing project will start soon. That's why I joined this forum - to gain some insights and participate in the experience and skill of others.
Now to the point:
I had two speakers during the past two years, one D120F and a D110F which both suffered from the same symptome: A hi-impedance voice coil. Examining that in detail I found on both speakers, that they had an interrupted voice coil wire right after the rivet (or solder lug) in the cone.
Scraping cautiously away the black glue - what material is that by the way? (footnote 1) - a white powder (instead of an aluminum wire) came to the light of day.
As if the aluminum had powderized itself (oxidized?) or reacted with some other chemical under the glue. I laid free a piece of the wire and wrapped a small spiral of copper wire around it and resoldered it to the rivet. (Soldering aluminum is critical, anyway - see footnote 2)
I would like to know if this problem of rotten wires is known or has been addressed in the past.
Thank you.
Christoph
Footnote 1: What liquid/glue is used to cover the voice coil wire on the cone surface?
Footnote 2: Is there any flux resin or something recommended to get these
aluminum voice coil wires soldered ? (I understand that voice
coils come with the wire ends tinned)