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I have some old Bose 802-II speakers, they crapped out on me at an event when our MC stuck the microphone under some drums... A little investigation revealed that 3 of the drivers have no continuity, I'm testing them right where the wires penetrate the cone, so there's a break in the circuit somewhere inside. I'll probably end up buying replacement drivers, but I'm still curious to know if there's anyway to get inside these and find the break without destroying the cones?

Any guesses what might be going on inside there, or what the fix might involve?

I understand it's hardly worth the effort, I'm mostly curious to know if it can be done.

enter image description here

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  • This isn't really on-topic for here, but tbh, if you can't see the break on a quick visual inspection - ie it really near the edge, or on one of the jumps to the solder tags, then forget it. Even if you have a coil-winder in your workshop, you'll never reproduce that specific wind. if they went massively over-current, then either one tiny section melted & went open-circuit… or it took out the 10 nearest winds too. – Tetsujin Jan 6 at 19:47
  • Thanks, may I ask where this question would be on-topic? And perhaps that a mod could kindly migrate this question where it ought to be? – ShemSeger Jan 6 at 20:55
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    There isn't really anywhere on SE that could cover this. i see your answer suggests it wasn't an overheat but pretty much a DC event - . It might be cheaper, long-term, to invest in some sort of op-amp protection. BTW, you really can't solder copper coils unless it's right at the point it jumps out to the tags. Soldering heat will take out a large swathe of nearby insulation. That's why I went straight to re-wind, which again isn't a DIY job. Wish you luck with the re-cones. – Tetsujin Jan 9 at 17:05
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Figured out what the problem was.

The two wires penetrating the cone go down to the voice coil, which in this case is an aluminum coil wrapped around a foil cylinder. The voice coil had sustained significant damage...

enter image description here

With copper coils, if you're lucky, it is apparently possible to lightly solder small shorts or breaks in the coil, but with aluminum coils there's nothing to be done except recone the driver with a recone kit and essentially completely rebuild the driver, or buy a replacement driver.

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