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View Full Version : le25 tweeter access to back of speaker to repair broken wire



bwireman
07-14-2012, 04:51 AM
jbl century l100 speakers, were tested and working, after transport one of the le25 wires is open.
measured ohmmage from the wire connectors to the wire going to the cone on both sides.
problem is located at the voice coil under the cone.
have removed the speaker and drilled out the rivots, to allow access for inspection.
question one, to remove the magnet/silver metal covering from the black frame, should i use heat gun
to loosen the glue.
have tried tapping with a rubber mallet, no success.
question two, when replacing the magnet to the previous location, should i clamp two wooden blocks
against the magnet to mark the position before removal.
have already used black marker to key the rivot holes when remounting the magnet.
question three, what glue is recommend to remount the magnet assembly to the frame.
this will be my first repair of a tweeter, and you feedback is greatly appreciated.
bwireman

hjames
07-14-2012, 05:00 AM
Suggest you just buy a fresh one here or off ebay ...
pulling the magnet assembly apart and expecting to get it all aligned again afterwards is pretty fiddly stuff ...

I believe originally they could de-magnetize them - do needed recones or whatever, reassemble, and remag them.

Those strong magnets make it pretty hard to realign everything afterwards otherwise.



jbl century l100 speakers, were tested and working, after transport one of the le25 wires is open.
measured ohmmage from the wire connectors to the wire going to the cone on both sides.
problem is located at the voice coil under the cone.
have removed the speaker and drilled out the rivots, to allow access for inspection.
question one, to remove the magnet/silver metal covering from the black frame, should i use heat gun
to loosen the glue.
have tried tapping with a rubber mallet, no success.
question two, when replacing the magnet to the previous location, should i clamp two wooden blocks
against the magnet to mark the position before removal.
have already used black marker to key the rivot holes when remounting the magnet.
question three, what glue is recommend to remount the magnet assembly to the frame.
this will be my first repair of a tweeter, and you feedback is greatly appreciated.
bwireman

bwireman
07-14-2012, 05:39 AM
once the magnet is pulled off the frame, to demagnify you can place it in the oven and pull out to test.
when the magnetic fields have been shut down, you could continue the repairs to the coil.
this should allow you to replace the frame onto the voice coil using the blocks of wood for positioning.
i could then use my stock of hard drive rare earth magnets pulled from old hard drives to remagnify
after gluing and inserting screws into the frame.

question, is the magnet assembly actually glued to the black frame, or is it using only the magnetic field to attach.
bwireman

hjames
07-14-2012, 07:00 AM
Pretty sure the pro shops use electromagnetic devices to demag & remag the old speakers.
Pretty sure popping it in the oven for a bake could affect other parts of the driver.
But its dead anyway, so you've got nothing to lose, right? and - its free.
Buying drivers is EXPENSIVE!

FWIW - its probably glued in place.


once the magnet is pulled off the frame, to demagnify you can place it in the oven and pull out to test.
when the magnetic fields have been shut down, you could continue the repairs to the coil.
this should allow you to replace the frame onto the voice coil using the blocks of wood for positioning.
i could then use my stock of hard drive rare earth magnets pulled from old hard drives to remagnify
after gluing and inserting screws into the frame.

bwireman

Earl K
07-14-2012, 07:34 AM
Heather is right of course, that the "easiest most direct route to a fix" is to simply get another . Mind you, I can understand the attraction in attempting the "herioc save" .

For inspiration and all-round good info, you should search out RobH3606(s) repair to a 2435H ( that he dropped resulting in a shifted magnet / toasting a very expensive driver ) .

He reglued it as well as recentered the gap ( so these things can be done ) . The 2435s neo magnet is stronger ( therefore it should be more difficult ) to deal with . His efforts resulted in an unexpected , happy ending .

You've got nothing to lose by trying your hand at a similar repair ( "necessity being the mother of invention" and all that ) .

:)

PS ; Robs great "driver-save" thread is HERE ! (http://www.audioheritage.org/vbulletin/showthread.php?11490-How-to-ruin-your-day&highlight=2435h+repair) ( bookmark it ! )

bwireman
07-15-2012, 11:09 AM
attempted to remove the rear cover on the le25 tweeter, used a low wattage heat gun with small nozzle directly heat the glue while a prying the frame up.
result, no movement, the glue must have a high temp. rating.
next, tried to insert a knife blade then an exacto knife moving side to side, again no movement.
how much force is necessary to brake loose the rear cover, while being careful not to damage the magnet.

have applied popsicle sticks to act as guides when replacing the cover.
added a few magnets, they help reduce the existing magnetic field size and strength, to help in removing the cover.
using a nail to test the field after installing the magnets, i found it would only attach lightly toward the outter edges of the cover.

question?, has anyone ever used gogone to help in removing the covers.
56291

POZiTRON
01-27-2014, 07:10 PM
more information:
http://www.audioheritage.org/vbulletin/showthread.php?33204-anyone-have-a-pic-of-le25-tweeter-with-back-the-cover-removed&highlight=LE25-2