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Beovox S45-2 woofer repair

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Thorstein
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Thorstein posted on Tue, Oct 10 2017 10:39 PM

Hello fellow B&O friends,

I recently bought a pair of s45-2s to pair with a Beomaster 4000 that I am currently replacing the capacitors on. The speakers sounded fine when I tested them, checked for any scraping noises etc and nothing seemed out of order. I decided to replace the capacitors in the speakers anyways as I guess they will be less than optimal being some 40 or more years old. 

Disaster however struck when removing the woofer on one of the speakers to gain access to the crossover: Just as I was lifting it out of its slot my cat jumps onto the table to see whats going on and causes the woofer to slip out of my fingers and drop down onto the cabinet. At the time I cursed the cat, prayed everything had gone well and proceeded with the capacitor replacement, but today, when I was about to put the woofer back into the cabinet I noticed a scraping sound when pushing on the woofer. It still moves back and forth but there is obviously something inside of it scraping against the magnet assembly.

Now I am not an audio service technician but as far as I can tell this must be the voice coil. Is it possible that the magnet has shifted ever so slightly causing the coil to rub against it, or could something have happened to the coil itself? Is this a viable repair, or should I go looking for a replacement unit?

 

 

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Craig
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Craig replied on Wed, Oct 11 2017 6:05 AM

Thorstein

I have repaired two of these woofers in the past where the magnet has become detatched, when this happens the magnet pulls to one side and grips the coil very tightly.....this doesn't sound the case with your speaker, however its unlikely that a drop into the cabinet would cause the ingress of any debris that would cause partial binding, if the cone has become misaligned this could put the coil out of true and cause the scraping you describe.

As for a course of action I would examine the cone at the diaphragm for any damage before I pulled the magnet off the frame, some pics may help in the diagnosis.....

Craig

Thorstein
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Thanks Craig. I'll see if I can get a few pics when I take off the dust cap to inspect the insides. Externally it looks ok, don't know if they are helpful but here are a few I took just now:

 

Craig
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Craig replied on Thu, Oct 12 2017 6:40 PM

I agree the pictures are not very informative, the speaker looks in good condition. However if the coil is scraping on the sides of the frame or the magnet core it will have to be centralised...this can be done and its not all that difficult....bit tricky and requires some patience. The diaphragm should be holding the cone and the coil centrally in the frame....if there is no obvious damage to the diaphragm and cone them your going to have to remove the magnet and reset it, afte rall you have nothing to loose by making the attempt.....check out my thread on this subject before you start, and good luck ;¬)

Dillen
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Dillen replied on Thu, Oct 12 2017 7:11 PM

It's possible that one or more voicecoil windings have fallen off the coil former.

Martin

Thorstein
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Thanks a lot Craig, certainly much more helpful than the audio repair shops I called, who basically all said to throw it in the trash. (With sarcastic undertones of "that's where it belongs anyways".)

 

Martin: If that is the case, would it be repairable? If not, do you know of any place i could get hold of original spec replacements? Modern equivalents are acceptable but I'd like to keep these as original as possible. After all I didn't hunt down these beauties to replace everything inside with something new.

 

 

Thorstein
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A little update from me on this, Martin was indeed correct that one of the windings on the voice coil had fallen off and was causing the slight scraping sound. 

Is regular old epoxy a viable option for gluing it back on, or would there be an issue with temperature? The glue I have on hand begins to fail at 80 degrees C according to the data sheet, is that to little?

Dillen
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Dillen replied on Mon, Oct 16 2017 9:34 PM

80 degC would be fine
I suggest you attempt a repair - you have nothing to lose, really.
If it fails let me know and I'll dig around in the dungeons a bit after a good used original woofer.
I am known to have a little of this and a little of that.

Martin 

Thorstein
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Thanks Martin, I'll send you a PM if the repair doesn't go my way.

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