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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Repir problem on Velodyne F-1800RII subwoofer speaker
I have a Velodyne F-1800RII that failed. One wire that connects to the voice
coil on the speaker has disconnected. There is a tab on the tube that the voice coil is wound on where braided cables attach to the voice coil wire. The braid and connection is then sealed under what looks like white epoxy. That epoxy separated from the tab it was one, allowing the braids to move and break their connection to the voice coil. To repair the connection, it seems I need to remove the epoxy from the tab to get to the voice coil wire I need to solder. Does anyone have any hints on how to proceed, which I imagine means removing the epoxy? I've thought about using my heat gun with a small tube to direct the heat at only the offending area, but don't know if this would be appropriate. If I need to carefully cut loose the rear spider from the voice coil tube to get enough voice coil to solder to, is it likiely that the coil is a bit below the spider so I won't damage it while cutting the glue joint between the spider and the tube? |
#2
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Repir problem on Velodyne F-1800RII subwoofer speaker
Bob F wrote in message
... I have a Velodyne F-1800RII that failed. One wire that connects to the voice coil on the speaker has disconnected. There is a tab on the tube that the voice coil is wound on where braided cables attach to the voice coil wire. The braid and connection is then sealed under what looks like white epoxy. That epoxy separated from the tab it was one, allowing the braids to move and break their connection to the voice coil. To repair the connection, it seems I need to remove the epoxy from the tab to get to the voice coil wire I need to solder. Does anyone have any hints on how to proceed, which I imagine means removing the epoxy? I've thought about using my heat gun with a small tube to direct the heat at only the offending area, but don't know if this would be appropriate. If I need to carefully cut loose the rear spider from the voice coil tube to get enough voice coil to solder to, is it likiely that the coil is a bit below the spider so I won't damage it while cutting the glue joint between the spider and the tube? With good forced ventillation, excavate it with an old soldering iron and a needle of some sort |
#3
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Repir problem on Velodyne F-1800RII subwoofer speaker
On Aug 12, 9:43*am, "Bob F" wrote:
I have a Velodyne F-1800RII that failed. One wire that connects to the voice coil on the speaker has disconnected. There is a tab on the tube that the voice coil is wound on where braided cables attach to the voice coil wire. *The braid and connection is then sealed under what looks like white epoxy. That epoxy separated from the tab it was one, allowing the braids to move and break their connection to the voice coil. Epoxy is used to make rigid connections, not flexible connections. The cone will flex and the wire should flex with it. The white glue should be some sort of emulsion. To repair the connection, it seems I need to remove the epoxy from the tab to get to the voice coil wire I need to solder. Does anyone have any hints on how to proceed, which I imagine means removing the epoxy? The glue should just peel off. You could carefully peel it with a razor knife. I've thought about using my heat gun with a small tube to direct the heat at only the offending area, but don't know if this would be appropriate. If I need to carefully cut loose the rear spider from the voice coil tube to get enough voice coil to solder to, is it likiely that the coil is a bit below the spider so I won't damage it while cutting the glue joint between the spider and the tube? This is more likely to fuch the speaker up royally. I wouldn't try it. For linearity, the coil should extend well out of the voice coil gap. Pull up the VC stub, and solder a bit of same gauge magnet wire to it to where the braid goes in. |
#4
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Repir problem on Velodyne F-1800RII subwoofer speaker
"Bob F" wrote in message ... I have a Velodyne F-1800RII that failed. One wire that connects to the voice coil on the speaker has disconnected. There is a tab on the tube that the voice coil is wound on where braided cables attach to the voice coil wire. The braid and connection is then sealed under what looks like white epoxy. That epoxy separated from the tab it was one, allowing the braids to move and break their connection to the voice coil. To repair the connection, it seems I need to remove the epoxy from the tab to get to the voice coil wire I need to solder. Does anyone have any hints on how to proceed, which I imagine means removing the epoxy? I've thought about using my heat gun with a small tube to direct the heat at only the offending area, but don't know if this would be appropriate. If I need to carefully cut loose the rear spider from the voice coil tube to get enough voice coil to solder to, is it likiely that the coil is a bit below the spider so I won't damage it while cutting the glue joint between the spider and the tube? I suspect the speaker most probably didn't fail, it was overdriven and was broken by a Human Being. If you force the cone to move way beyond its limits, it will indeed eventually pull its own braids out to stop the torture. I gave up years ago trying to repair this sort of damage as it never holds up for very long. Mostly because the user is incapable of understanding that it was him that broke it, so quickly breaks it again, but also because it is very difficult to make a proper flexible repair using solder. Gareth. |
#5
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Repir problem on Velodyne F-1800RII subwoofer speaker
"Gareth Magennis" I suspect the speaker most probably didn't fail, it was overdriven and was broken by a Human Being. ** Still called a failure by most. If you force the cone to move way beyond its limits, ** That should never be possible using electrical input alone. It is simple enough to arrange things so the voice coil moves out of the magnetic gap and loses most of the driving force before mechanical damage occurs. However, some sub woofers are designed (?) with very long voice coils rendering this precaution impossible. Such woofers are bound to fail. it will indeed eventually pull its own braids out to stop the torture. ** That should not be the case - easy to make the braids long enough so any possible excursion is allowed I gave up years ago trying to repair this sort of damage as it never holds up for very long. ** Fitting longer braids is possible, done that a few times. I had one job where the two braids had welded together half way along - the maker ( Alesis ) had arranged to braids to vibrate towards each other and touch if enough level were applied. Shortening each braid fixed it. Mostly because the user is incapable of understanding that it was him that broke it, so quickly breaks it again, ** Had one guy who repeatedly damaged his JBL K120s this way. He had them in an open backed 100W Marshall combo amp and played BASS guitar through them. JBL specifically warn against doing this with the K120s. ...... Phil |
#6
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Repir problem on Velodyne F-1800RII subwoofer speaker
"Phil Allison" wrote in message ... "Gareth Magennis" I suspect the speaker most probably didn't fail, it was overdriven and was broken by a Human Being. ** Still called a failure by most. If you force the cone to move way beyond its limits, ** That should never be possible using electrical input alone. It is simple enough to arrange things so the voice coil moves out of the magnetic gap and loses most of the driving force before mechanical damage occurs. However, some sub woofers are designed (?) with very long voice coils rendering this precaution impossible. Such woofers are bound to fail. it will indeed eventually pull its own braids out to stop the torture. ** That should not be the case - easy to make the braids long enough so any possible excursion is allowed I gave up years ago trying to repair this sort of damage as it never holds up for very long. ** Fitting longer braids is possible, done that a few times. I had one job where the two braids had welded together half way along - the maker ( Alesis ) had arranged to braids to vibrate towards each other and touch if enough level were applied. Shortening each braid fixed it. Mostly because the user is incapable of understanding that it was him that broke it, so quickly breaks it again, ** Had one guy who repeatedly damaged his JBL K120s this way. He had them in an open backed 100W Marshall combo amp and played BASS guitar through them. JBL specifically warn against doing this with the K120s. ..... Phil I've seen a lot of Peavey black Widows with broken braids, mostly 15" drivers from the 1 x 15 bass bins. Is there anything about their design that makes them more susceptible to this than other models, or are there just a lot of Peavey bass bins out there? Gareth. |
#7
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Repir problem on Velodyne F-1800RII subwoofer speaker
"Gareth Magennis" I've seen a lot of Peavey black Widows with broken braids, mostly 15" drivers from the 1 x 15 bass bins. ** Fatigue failures - not being yanked off by force. There is only so much a piece of cotton cored tinsel can take. .... Phil |
#8
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Repir problem on Velodyne F-1800RII subwoofer speaker
spamtrap1888 wrote:
On Aug 12, 9:43 am, "Bob F" wrote: I have a Velodyne F-1800RII that failed. One wire that connects to the voice coil on the speaker has disconnected. There is a tab on the tube that the voice coil is wound on where braided cables attach to the voice coil wire. The braid and connection is then sealed under what looks like white epoxy. That epoxy separated from the tab it was one, allowing the braids to move and break their connection to the voice coil. Epoxy is used to make rigid connections, not flexible connections. The cone will flex and the wire should flex with it. The white glue should be some sort of emulsion. This really does seem to be epoxy. It is hard and brittle. To repair the connection, it seems I need to remove the epoxy from the tab to get to the voice coil wire I need to solder. Does anyone have any hints on how to proceed, which I imagine means removing the epoxy? The glue should just peel off. You could carefully peel it with a razor knife. I tried snipping between the two leads, and separated the damaged one. The covering came off in flying chips. Very brittle stuff. Unfortunately, the voice coil wire coming out is broken off right where it comes out between the rear spider and the tube of the voice coil, so I am going to have to separate the spider from the voice coil tube a bit to repair it. It appears they used the same glue to glue the spider to the tube. This speaker is interesting. It has the normal front spider, and another at the back of the magnet assembly. The two are maybe 5 inches apart. I've thought about using my heat gun with a small tube to direct the heat at only the offending area, but don't know if this would be appropriate. If I need to carefully cut loose the rear spider from the voice coil tube to get enough voice coil to solder to, is it likiely that the coil is a bit below the spider so I won't damage it while cutting the glue joint between the spider and the tube? This is more likely to fuch the speaker up royally. I wouldn't try it. For linearity, the coil should extend well out of the voice coil gap. Pull up the VC stub, and solder a bit of same gauge magnet wire to it to where the braid goes in. You are suggesting that if I can get a hold on the wire, I can just pull a little loose from the coil to get enough to solder to? Thanks for your help. |
#9
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Repir problem on Velodyne F-1800RII subwoofer speaker
"Phil Allison" wrote in message ... "Gareth Magennis" I've seen a lot of Peavey black Widows with broken braids, mostly 15" drivers from the 1 x 15 bass bins. ** Fatigue failures - not being yanked off by force. There is only so much a piece of cotton cored tinsel can take. ... Phil I replaced one of my customers' Peavey baskets which had a detached braid, and told him he was probably overdriving his speakers. 6 months later he came back and the new basket had suffered the same damage. Either he IS overdriving it, or it is suffering from some sort of Bang, Pop thing coming out of his amplifier. I can't see a speaker failing, in weekend use, from fatigue in 6 months. Curiously, neither of the voice coils showed any abnormal signs of overheating. Gareth. |
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