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The mid on one of my prized L100's has stopped working. No sound at all is coming out of it. The cone and the surrounds look fine ... anybody know whats going on here? Is it a disconected lead or something like that? The tweeter and woofer are functioning properly. Any help would be great.
Measure the voice coil resistance, i.e., across the terminals of the disconnected driver....
I have a couple of these that have good continuity through the voice coil, but still no sound. As Gordon has mentioned here before, there is a tendency for the wire of the voice coil to come loose from the former. The glue just fails.
Have you taken the driver out yet?If not try moving the midrange control around,sometimes the pots get crappy and no contact.
I had an LE5-12 quit because one of the wire pairs in the cone no longer made contact. A few seconds with the soldering pencil took care of it.
It does seem, that due to the combination of paper former and the glue JBL used on the LE5-2 voice coils at that time, that probably, almost all LE5-2s will fail eventually, due to failure of the glue holding the coil windings to the former. I've come to believe that at least in some cases, it's got nothing to do with abuse or over-zealous SPL levels... it's just a factor of plain material failure.
Fortunately, these can be readily reconed. There's factory kits available from JBL at most times, or for less money (approximately $55-$65 including parts and labor usually, as opposed to about $120 or so for the factory recone kit), there are some pretty faithful (as in accurately-replicated cones and voice coils) aftermarket recone parts available. It's possible to recone one of these using these aftermarket parts, and afterwards wind up with something that's darn difficult to discern from a stock factory unit, both in sound and in appearance. But, if authenticity is your primary goal, there is still the factory recone-kit option, for those willing to pony up the cash for it...
Regards,
Gordon.
I'm pulling the driver out now ... time to break out the multimeter! Thanks for the advice, hopefully this isn't a huge deal.
So I pulled the driver, and it looks ok, but the entire speaker now doesnt sound. I fiddled with the crossover trebel/bass knobs, and then I got no sound. Could this be a crossover problem? If so, how do I get it out of the cabinet? Any of you people have schematics for the crossover? I'm at a total loss here. Also, there was zero slack in the wires to the mid driver. Is that standard?
Search the site for the crossover schematic, it is very simple.
Sounds like the adjustable controls are giving you grief. Try cleaning the pots that control the midrange volume
There is nothing but wire connecting the woofer to the crossover, then to the rear terminals. No L-pads or components in that circuit. So if there is no sound from the woofer, look for a bad connection.