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Wagner
09-04-2015, 09:17 PM
I have two about ready to go back in their cabs
I have noticed that their male and female faston lugs can move
The core of the rivet appears to remain stationary, but the little lugs themselves can move
Not flopping loose but still can be moved
I have had conductivity issues develop all the way to infinite resitence with old Isophon drivers using this same attaching technique for wire lugs: the pressure or friction fit of only a brass rivet
Although they are working now, it's only a matter of time before corrosion/oxidation finds it's way into the crack as "rust never sleeps"
May even be an issue now, even if it's not audibly apparent yet
I am contemplating hitting these with a light tack of solder
Mistake? Anyone noticed, experienced or addressed this issue?
The tweeters work well but I'm just not crazy abot the fact that the connection is not tight
Best I can tell from photos and memory, the voice coil wires are attached via solder on the opposing side of the rivet and the rivet is isolated from the frame with a grommet
Anyone know what this grommet is made of and how tolerant of heat it should be?
My only other (real concern) is that even the momentary heat from a tack job may spoil my fresh foam diffusers
Wish I had noticed this beforehand!

What say ye? Tack them or leave them alone?

jarrods
09-04-2015, 09:50 PM
I'd be worried may damage foam. Have you considered an Electrically Conductive Adhesives? No heat required.

Wagner
09-05-2015, 12:34 PM
I'd be worried may damage foam. Have you considered an Electrically Conductive Adhesives? No heat required.

Yes I have, but the cost(s) are prohibitive for any formulation that has well documented efficacy (and I am still skeptical,there does not seem to be a unanimous consensus for any of them)
They also all seem to be recommended for extremely low voltage applications
Foam diffusers (assuming that is all that I ruin :)) are only $10 a pair
One example:

http://www.amazon.com/MG-Chemicals-Conductive-Extreme-Conductivity/dp/B00AJVAT3S/ref=cm_cr_pr_product_top?ie=UTF8

NickH
09-05-2015, 12:43 PM
Can you just re rivet it?

If not what about a screw and nut.

Nick

SEAWOLF97
09-05-2015, 12:53 PM
melt a drop of solder on them, if concerned.

I think they were pretty loose , even when new.

audiomagnate
09-05-2015, 01:08 PM
I've seen them like that. I wouldn't worry about it, but you're not me.

Wagner
09-05-2015, 01:10 PM
melt a drop of solder on them, if concerned.

I think they were pretty loose , even when new.
Now we're talking; thanks for that insight; let's get
Figured as much, but while I've got everything all apart 'em and hper scrutinizing everything just wanting 'em "to be all that they can be" :)
Just now noticed it for the first time during this restoration; pretty shitty Assembly if you ask me for a JBL product from the glory days (and these tweets are unmolested virgins to boot, so it's not s result of mishandling)

After all of this effort, I just optimal conductivity

Installing a stud for that magical 4th network screw as well; this'll be the first and the last time these foilcals will ever have to come off; what a DUMB ASS move that was

Already ticked; after a careful and complete strip and sand of the front baffle, hardwood doweling of the driver mounting holes (the old particle board strip outs), Famowood filler repair of all the small imperfections and about 2 pounds of pure black lacquer, I've still got particle board grain showing on the end cuts....................debating whether to just let it ride or do it again (edge clean up is a chore on a baffle redo with veneer in place) and I hate tape up/masking

They look fantastic, just not all smooth as original (although I have sen original factory cabs with more flaws in them than these) and my wood screw holes are nice and tight now (used Oak) Wanted to go with T-nuts but JBL cut the shit so close to the mid-range cup it was a big nix nix on that one

How you been man? Happy to tell you my boy is finally back from Afghanistan, hopefully for a while

Word is though that we're heading back to Iraq, and in a big way, not Nobama's bull shit drone strikes but people's kids on the ground (again)

SEAWOLF97
09-05-2015, 04:03 PM
Now we're talking; thanks for that insight; let's get
Figured as much, but while I've got everything all apart 'em and hper scrutinizing everything just wanting 'em "to be all that they can be" :)
Just now noticed it for the first time during this restoration; pretty shitty Assembly if you ask me for a JBL product from the glory days (and these tweets are unmolested virgins to boot, so it's not s result of mishandling)

How you been man? Happy to tell you my boy is finally back from Afghanistan, hopefully for a while

Word is though that we're heading back to Iraq, and in a big way, not Nobama's bull shit drone strikes but people's kids on the ground (again)

you want to see shitty ? Mission UK cabs from the 90's. Fall apart in your hands, so sloppy. fortunately the drivers were good. Looked like cabs were built in some 4th world country by blind beggars.

glad to see your son is back in 1 piece. Most likely changed him a bit. Give him some space for a while. Hope you are wrong about Iraq. :(

Wagner
09-05-2015, 05:06 PM
I've seen them like that. I wouldn't worry about it, but you're not me.
Understood
Clearly they've been this way for 40 plus years (and still work)
Still, I'm a fan of clean and tight electrical connecions
If the lug can move it's not as good as it could be, especially long haul
(I'm hoping one of my children will still listen to these things from time to time long after I'm dead and gone)
I know my Son will
Ergo the obsession with prophylactic perfection to coin a phrase
I try to address every potential failure mode I can think of with all of my restoration work be it electronics, furniture, automobiles or speakers
Robs some of the joy from the hobby, but my customers and friends sure appreciate my mental disease! :)