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Beovox S45.2 woofer repair - unglued magnet, stuck woofer

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Irata
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Irata posted on Sun, Jan 22 2017 1:18 PM

Thought I'd add another thread about repairing a pair of S45.2s.

Following the basic concepts from Orava http://forum.beoworld.org/forums/p/1243/10546.aspx#10546

and Machineage http://forum.beoworld.org/forums/p/4738/42890.aspx#42890

I was able to repair my stuck woofers. I got a really nice set of 45.2s of eBay, listed as parts or repair. I took a chance and when they arrived both woofers were locked up solid. Not something I've come across before.

After opening up the cabinets to see what the hell was going on in there, I saw the magnet just lying in the back, voice coil exposed. I couldn't tell if someone had already tried fixing them, or if they had just fallen off.

Luckily a few guys on here had success in repairing them, so I figured I'd give it a shot.

 

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Irata
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Irata replied on Sun, Jan 22 2017 1:23 PM

After having removed the second woofer, which still had the magnet attached, I removed it with a tile wedge and a couple taps from a 5 lb sledge. Popped off easy enough.

It definitely had a lot more glue residue than the other, so either someone before me had cleaned off the one in trying to repair, then gave up, or there was almost no glue on from the factory.

Next step was to clean off all the old epoxy. I taped off the voice coil so I didn't damage it. Then I took it to my wire wheel to clean off all the garbage. It took a little while, but it's a lot less effort than doing it by hand or with chemicals.

I cleaned off the magnet surface the same way. Those went quickly.

Irata
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Irata replied on Sun, Jan 22 2017 1:28 PM

Taking the dust covers off wasn't too tricky; I used a heat gun to soften the old glue, a small screwdriver to pry up the edges as I gently pushed through the bottom with my finger. I left it in place at the wires to save a little work and taped them out of the way.

This way I didn't have to cut through the dust covers at all, they stayed completely intact.

 

Irata
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Irata replied on Sun, Jan 22 2017 1:33 PM

The pole pieces had some corrosion on them, and were scratchy as I dry fit the pieces together. So I sanded the sides with 220 grit sandpaper to take down most of the crud. Then I followed that with 600 grit. 

Don't know if it matters or not, but I made sure to go up and down the sides, so as not to cause any cross grain scratches with the voice coil's path of travel. They shouldn't be touching when finished, but I figured might as well try to make things work smoothly.

After

Irata
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Irata replied on Sun, Jan 22 2017 1:34 PM

I'm sure this was overkill, but then I took the pole pieces to a buffing wheel, and hit them with some emory compound. These aren't visible show pieces, so I didn't go crazy and get a mirror finish, but I wanted them to be pretty dang smooth.

Irata
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Irata replied on Sun, Jan 22 2017 1:39 PM

Here's where I took a shortcut from Orava's process, and traveled the machineage path.

I did not remove the surround, cone and spider from the frame. I left those alone since everything was still intact. I figured I could then just straighten everything up around the pole piece.

Magnets and pole pieces ready for gluing:

 

I put the magnet in a vice to hold it in place. Found what appeared to be center and clamped it in place. On one of the magnets, the old adhesive was still in the center and I was able to use that as a guide to center. On the other I had to go with a bit more of a gut feel.

 

Irata
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Irata replied on Sun, Jan 22 2017 1:42 PM

I let those dry for a few hours before attempting to line up the cone/coil. Again, using the base locked in a vice so I only had to move the frame/cone/coil, with a bit of fiddling around and using some thick paper shims, I was able to get them aligned with free movement up and done and no rubbing/scratching of any kind.

Irata
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Irata replied on Sun, Jan 22 2017 1:46 PM

Once they were in place, I put a thick bead of epoxy around the edges to lock them in. There's no glue between the magnet and frame, but that didn't work too well from the factory anyway.

I ran a little bead of speaker glue following the old glue line from the dust cap, and gently eased it back into place. It held nice and tight and I didn't need to weight it with anything to keep it in place.

I let them dry overnight. Here's on little patient fresh out of surgery this morning:

Irata
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Irata replied on Sun, Jan 22 2017 1:49 PM

Almost exactly 24 hours after having started this project, I now have 2 fully functional and beautiful S45.2s back in business!

I'll also note that this is the first time I've ever been inside a woofer, and managed to successfully complete this repair in a day, so I don't think anyone should be too intimidated by the process.

Dillen
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Dillen replied on Sun, Jan 22 2017 1:56 PM

Nice work!

Martin

Peter
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Peter replied on Sun, Jan 22 2017 10:42 PM

I echo that - lovely bit of work and well documented. Thank you.

Peter

Rich
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Rich replied on Mon, Jan 23 2017 1:57 AM
Well done, sir. Now find some P45s and save them!

Blah blah blah, blah blah ba ran

Irata
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Irata replied on Mon, Jan 23 2017 7:49 PM

Thanks guys, fun work this weekend.

Though, it got me thinking as I was driving around. Now that I know what everything is, and how they all function physically...

I have no idea what sort of sorcery makes these things work. The more I think about it, the weirder it becomes.

You've got a magnet, a piece of wire to receive electric impulses, and a piece of paper. And out of that comes symphonies, jazz vocals, crushing death metal, thundering rap, thumping electronica...

From the simplicity of one vocalist's voice, to a hundred piece orchestra, all coming out of the same speaker.

The idea that this works is some crazy witchcraft black magic. I like fixing them, but thinking about why it works mildly terrifies me.

DMacri
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Irata:

The idea that this works is some crazy witchcraft black magic. I like fixing them, but thinking about why it works mildly terrifies me.

Don't worry- it's not magic. It's a function of electro-motive force. An electro-magnet interacting with a permanent magnet.Big Smile

Dom

BeoSystem 5000, BeoSystem 6500, AV 7000, BeoSound 4000, Playmaker, BeoLab 2500, BeoVox S-45, BeoVox S-45.2, RL-140, CX-50, C-75, CX-100, 3 MCL82 link rooms, A8 earphones, A3, 4001 relay, H3, H6, and ambio 

Irata
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Irata replied on Tue, Feb 7 2017 12:11 AM

Exactly. Black magic voodoo. 

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