Realigning the pole piece

[boputnam]

OK, doods, here's a heartbreaker...

Beauty vintage driver, just reconed arrived ruined during shipping by FedEx. FedEx is honoring the claim in full, but the damage is done.

The motor popped off the basket and jumped out of position. The vc was not damaged, but it matters not. Things are not right. The bostik glueing the motor to the plate had dried-out and become brittle - it could not stand the physical shock. THIS IS THE BIGGEST RISK WITH SHIPPING VINTAGE DRIVERS.

I struggled with how to get the motor off the basket and devised the boimechanics pictured. Plywood on my chest, wooden pole, wooden cup over the vent and a two-arm pull. Easy as pie.

Now, is there any way to realign the pole piece in the plate? On resetting, the basket/plate want to rest against the pole piece. Very strong magnetic flux right there (by design). The entire motor is held in-place by bostik - no algnment holes, no nothing but the gap.

Has any one done this successfully, or know a shop that does? JBL Pro will not...

[boputnam]

...

[Zilch]

Has any one done this successfully, or know a shop that does? JBL Pro will not...

Sure, Audivex, assuming the break was clean at the glue line and the magnet not fractured.

It's time you came over here for a visit, anyway....

[boputnam]

Wow - thanks, Zich! There is no break - just the bostik let go of the plate. No fracture to the magnet.

You're right - overdue for that... Festival season is soon coming to an end - that will free-up a lot of the lost weekends...

[Ken Pachkowsky]

There is a nice looking pair of what are becoming very hard to find drivers. Hope you can save it Bo.

Ken

[Guido]

This recone is perfect!!! I can guess who did it.

Save this speaker Bo! Good Luck...

[boputnam]

This recone is perfect!!! I can guess who did it.

An artform unto itself...

[Ian Mackenzie]

Bo,

Had you thought about using a shim like in recone kit.

I have a 2122 recone kit and I just looked at the shim, it would not be strong enough. You might be able to get one machined out of brass or aluminium. But perhaps it would be better to find a good fitter and turner. This is what they are trained for.

Ian

[Thom]

God I love alnico. I dropped a D130 and knocked it slightly out of alighnment. Recone would have cost more than what I payed at the swap meet. I determined which way the magnet had to move, smacked it with a 2x4 twice, good as new. Now as to your problem, I didn't even know they glued together. I had the rivets loose on an LE5, bought it that way so I don't know how it happned but were talking real loose, removed them with a dremol and replaced them with brass cap screws, but if this happened shipping than anyone who cones for a touring band must have seen it, so I'd look for someone who cones for touring groups. My experience has always been that if they are on jbl pro's list they probably won't admit to doing anything the factory doesn't do. There is a guy in sacto, His father started a shop there over 50 years ago. Don't know if he currently has a shop or is working from his garage. but if there is a way to do it he probably knows it. I'm not trying to say "he's the greatest". There are probably good people closer, but if you strike out his name is Ron Neil and if he currently has a shop it's probably called neils speakers. If this happened to yours while packaged fairly well, touring speakers shipped mounted must get more stress than that. It would seam that it would be as simple as the right glue and the right fixture. Have you seen this before? I think there are a couple of speakers on ebay like that right now.

[boputnam]

Had you thought about using a shim like in recone kit. ... I have a 2122 recone kit and I just looked at the shim, it would not be strong enough.

I did, but I agree. Plus, the shim is slightly thinner than the gap. This job needs a spacer ring at the gap size.

I think I now know why so many drivers have the same diameter voice coil - I need that spacing ring, dammit...

[Ian Mackenzie]

Yep, thats a given my friend.

A shop would be able to spin one off for you. The amazing Widget ..he may know someone.

Ian

[subwoof]

You think that JBL would of invested in a few screws to keep them together????

Nah - an extra 40 cents. The original gray ferrites actually did. BUT the screws would bend anyway from the heavy weight because they were non-magnetic softies.

Anyways that magnet is the same one as the 2214 ( they did reuse them all over the place ) - I happen to have one sitting in the shop with a cracked frame from the same "boys in brown" treatment

Forget the blood blisters - send me an address and it's yours.

I have sent a number of them to be re-cemented and NO it cannot be done with any amount of accuracy unless the ferrite is demagg'ed and even then I still had only a 75% success rate.

Overall not worth the expense.

sub

[boputnam]

Hey, sub!! Haven't talked to you in over a year!

Lemme first see what this dood in the East Bay can do - I think this can be restored. Thanks for the really generous offer.

[Robh3606]

Hello Bo

That stinks!!! I just went through this with a 2435 and it was difficult to do. You need shims made up that are about .001/.002 less that the gap. If you try to go dead on it will jam. You need some play to be able to position them. Figure one of them you will have to pull out with pliers so make sure you have a pull whole in it and you lubricate them as well. If I were you I would take Sub up on that frame.

Rob

[subwoof]

I noticed you cut out the spider.



Since this was a recent recone, a liberal dosage of MEK would of softened the glue and you can then seperate it with a well worn small flat blade screwdriver ( #1 ) . Knife blades are somewhat risky.

If you then unsoldered the leads, you could of saved the kit ( sans foam of course).

One trick is to use a stanley 3/4 wood chisel ( their steel is the best ) and seperate the mag from the piece that shifted with some love taps from a nearby hammer.

Now get a handful of pig stickers ( massive flat blade screwdrivers ) to act as levers, shims and finger protectors.

Then use a sucession wood shims until you can lift away.

At this point you can stop and you will have a PERFECT passive radiator.

At 190.00 for a recone, it's worth the risk. Done this many times and usually the cone survives.

sub

PS- the 128H mag is the same too.