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View Full Version : L100 woofer screws stripped?



Puddintane
03-17-2013, 10:40 PM
I'm hoping someone can help out a JBL noob here. I have a pair of L100s, and the mounting screws on one woofer seem to be stripped--or else they're seized up in the anchors, and it's the anchors that are turning in the cab. I think it's probably the latter. Any suggestions on how to get at these so I can pull the woofer? Any and all advice would be greatly appreciated.

rdgrimes
03-18-2013, 05:18 AM
Usually its the t-nut spinning loose. If you can get the other screws out, try gently prying up the speaker flange while turning the screw.

Puddintane
03-18-2013, 12:55 PM
Usually its the t-nut spinning loose. If you can get the other screws out, try gently prying up the speaker flange while turning the screw.

Unfortunately, none of them will come out. They're all doing the same thing. It's as if they were put in with Loctite or something.

rdgrimes
03-18-2013, 01:02 PM
That's some pretty old MDF, and the t-nuts routinely come loose. that doesn't rule out some nitwit putting loctite on the threads some years ago, or they are just rusted.

Worst case you remove the mid or tweeter and go in that way to grab them. You may have to knock loose the isolation can behind either one of those. Patience is a virtue in this situation. Plan on needing new t-nuts when its all done.

subwoof
03-18-2013, 02:35 PM
if you drill the center of each bolt with a series of increasing size bits ( 1/8 to 3/16 ) the head will simply break off from the shaft. The depth is just a little deeper than the bottom of the "+"

You can jam a very small finishing nail in between the head and speaker frame if needed.

use a shop vac to suck away the metal shavings while drilling.

Most often the bolt ( and/or ) t-nut is corroded.

been there many times...it's always the consumer models that have this issue...wonder why..??

Puddintane
03-18-2013, 05:37 PM
That's some pretty old MDF, and the t-nuts routinely come loose. that doesn't rule out some nitwit putting loctite on the threads some years ago, or they are just rusted.

Worst case you remove the mid or tweeter and go in that way to grab them. You may have to knock loose the isolation can behind either one of those. Patience is a virtue in this situation. Plan on needing new t-nuts when its all done.

It's been a while since I was working on them and ran into the problem. But if I recall correctly, I pulled the mid and there was some kind of port tube or something behind it. The idea at the time was to try and get hold of the back end of it with a vise grips or something. But the way they're made (with the port tube or whatever it was) meant it wasn't simply a matter of displacing some insulation. I'll have to pull it again to check, but that's about where the process stalled the last time I messed with them.

Puddintane
03-18-2013, 05:40 PM
...been there many times...it's always the consumer models that have this issue...wonder why..??

Have you really had to do this before?

Argh! That's kind of what I was hoping I wouldn't need to do.

Don C
03-19-2013, 08:08 AM
You might try pushing in the plate on the back that the terminals are fastened to. Just push it into the cabinet by tapping with the handle of a hammer. It's usually held in place by a few staples. It's behind the woofer, and the hole is a bit bigger than the tweeter hole. You will have to use a few screws to put it back in place later.

badman
03-20-2013, 09:25 AM
I recently had this problem with 2206h in a cab- removed the non-spinning screws (only one had come loose) and had to leverage the driver and cut the bolt out with a hacksaw.

Big fun!

But fortunately only minor damage to the replaceable cabinet, driver's fine.

Don C
03-20-2013, 10:37 AM
Part of the trouble is that you sometimes have to push in hard on the screwdiver while turning to keep the tip from slipping in the screw, but pushing on the screw while turning also tends to push the T nut out of the back of the baffle. Prying up on the woofer while trying to remove the screw can help in this case. Too bad that woofer is often stuck to the baffle and can't be pried up. It's a struggle many of us have been through.

subwoof
03-21-2013, 12:09 PM
home depot has a small blue thin metal prybar that can be "tapped" under the frame where the problem screw(s) are....this might do the trick - and the most important thing about these restorations is use NEW, high quality screwdrivers with the right tip size!

Those cheapo wonder sets or anything you've had for years is useless for this app....:)

BTW - look at the next post to see EXACTLY what a dull phillips screwdriver does to a speaker...!

http://www.audioheritage.org/vbulletin/showthread.php?34210-My-JBL-K-140-need-some-care-!

SEAWOLF97
03-21-2013, 12:34 PM
Part of the trouble is that you sometimes have to push in hard on the screwdiver while turning to keep the tip from slipping in the screw, but pushing on the screw while turning also tends to push the T nut out of the back of the baffle. Prying up on the woofer while trying to remove the screw can help in this case. Too bad that woofer is often stuck to the baffle and can't be pried up. It's a struggle many of us have been through.

absolutely correct ..take out all the screws that you can , break the woofer loose by laying on its face, pick up one edge 4-5 inches and let drop (do on carpet) ....when some have come out, you can lift that area ..putting pressure on the stuck one, securing it so no T-nut turn and then try to back out the screw.

worst case ...drill out the screw head or grind off.

Mike F
03-21-2013, 05:18 PM
home depot has a small blue thin metal prybar that can be "tapped" under the frame where the problem screw(s) are....this might do the trick - and the most important thing about these restorations is use NEW, high quality screwdrivers with the right tip size!

Those cheapo wonder sets or anything you've had for years is useless for this app....:)

BTW - look at the next post to see EXACTLY what a dull phillips screwdriver does to a speaker...!

http://www.audioheritage.org/vbulletin/showthread.php?34210-My-JBL-K-140-need-some-care-!

LOL, I made that very same mistake once.......:banghead:

hjames
03-21-2013, 06:38 PM
Part of the trouble is that you sometimes have to push in hard on the screwdiver while turning to keep the tip from slipping in the screw, but pushing on the screw while turning also tends to push the T nut out of the back of the baffle. Prying up on the woofer while trying to remove the screw can help in this case. Too bad that woofer is often stuck to the baffle and can't be pried up. It's a struggle many of us have been through.

Go get a Dremel moto-tool and grind the heads off those screws right now -
don't gamble - why risk punching out your cones with a screwdriver or anything less.

Puddintane
03-21-2013, 08:13 PM
Go get a Dremel moto-tool and grind the heads off those screws right now -
don't gamble - why risk punching out your cones with a screwdriver or anything less.

That may be what I'll end up doing. I actually have a Dremel 3000 kit that was just given to me as a gift, and I haven't even tried it out yet. This may just be it's initiation!

Woofer
04-01-2013, 06:50 AM
That may be what I'll end up doing. I actually have a Dremel 3000 kit that was just given to me as a gift, and I haven't even tried it out yet. This may just be it's initiation!

As already mentioned, be extra aware, that whatever you do, (drill or grind), that you will have metal filings/grindings everywhere, and that stuff will kill your speakers. I can't stress that point enough.
If this is all new to you, then get some newspaper and tape/mask off the immediate work area to catch all the debris caused. Better to be slow and cautious rather than be quick, and sorry...
It pays to keep a vacuum running with cleaner nozzle pointed at the job, as subwoof suggested in his post or a small magnet handy close to your working area to attract these bits before your speaker magnets do.
I've done lots, and I prefer to drill, and again as subwoof suggested, start small and work your way up, drilling just deep enough to only take the head off and let the bolt and t-nut fall through.
You will have to apply a little pressure from the side of the head or just under it if there's enough of a gap with a small flat screwdriver to stop the head from spinning though.

Good luck, and let us know how you go.

sonofagun
04-01-2013, 02:59 PM
I think going in thru the back is best - like someone suggested, knock in the terminal plate on the back - you could then make the hole bigger with a drill or saw giving you plenty of access to the back of the woofers. You can fill the hole in later.