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View Full Version : JBL 4311 pot cleaning question!!!



gotmojo
10-19-2008, 08:48 PM
Hey all,
I have pair of 4311's and a pair of L88 Plus12's with super scratchy presence/treble controls. I need to get to these pots to spray "em out with Caig cleaner, but see no way to get at them without tearing off and ruining the aluminum stick on labels. Taking out the woofers seems to be one access, but it'll be blind or require a mirror to do it. Any tips here?
Thanks,
James

invstbiker
10-19-2008, 11:37 PM
James, I've used a hair dryer before on the foilcals with great success. A little heat and they peel off to get access to the screws. Once you get the L-pads fixed up get some 3M spray on glue and replace your foilcals.

Good Luck

Regis
10-20-2008, 08:46 AM
James, I've used a hair dryer before on the foilcals with great success. A little heat and they peel off to get access to the screws. Once you get the L-pads fixed up get some 3M spray on glue and replace your foilcals.

Good Luck

That is the 'tried-and-true' technique that works very well. You may also want to get a very thin and flexible putty knife to work under the decal carefully. That will help speed up the process of removing the decal intact. Patience will get you an undamaged decal or foilcal!

gotmojo
10-24-2008, 09:26 AM
Thanks for responding! The hairdryer and some patience paid off well. Got the plate of in good shape, but in these old speakers there is no removable panel for the pots! These actually were originally L88's that I bought in '73 after my freshman year in college, and they already had the midrange speaker hole covered with a plate. The next summer I saved up my money and bought the midrange kit to convert them to L100's - well worth it! Been listening to 'em ever since. Interestingly the name plate says model L88 Plus 12 (adds up to 100!) - purty creative of them JBL boy's back then. Back then I somehow had to add the Presence control, but don't remember how I did it - had to be that I removed the woofer to get in there - almost seems like I can remember that, but dang, its been 34 freakin' years. Anyway, thats my plan for today - to pull the woofer out and see if I can spray those pots out so they work OK. If anyone has a better idea, please post it quick! 'Cause I got four of these speakers to spray today!!!! By the way, right now I have the "new" Ry Cooder "I Flathead" playing on these bad boys and, course, sounds awesome. Life is good, if a little challenging. gotmojo

gotmojo
10-24-2008, 11:08 AM
OK. So, on the kitchen countertop, I have the woofer removed, and the midrange presence pot is removed but resides in a aluminum box that has no entry way. There is a hard cork layer on the front of the box - the side with the presence knob - and I imagine there are some screws under there to take the face off, but this cork sheet will be totally ruined to take it off. Any knowledge of where the screws are so that I can take just a little of the cork off? The little woman comes home in 3 hours. Not good.
gotmojo

gotmojo
10-24-2008, 11:47 AM
OK, OK, OK. So I scraped some cork off the corners: Not screw, rivets. So I drill a hole in the aluminum housing directly opposite the poles and was able to slip a cleaner spray tube thang into one of the pole holes and spray into that. Hope it works!
gotmojo

gotmojo
10-25-2008, 12:40 PM
So ............ Peeled off the aluminum face plate sticker thang with the hair dryer and a putty knife. Tthen I drilled a hole (over the spot where the screw is) in the faceplate sticker thang so if I ever have to do get at it again, I can get to the screw with out so much risk and trouble. Its a small blemish but seems so functional! Removed the woofer to get at the Potentiometers. Drilled the hole in the box to get access to spray the presence potentiometer, sprayed it and the brilliance one. Reassembled. Used a hole punch and hammer to cut a hole in the other speaker nameplate sticker thang so I could get to the screw, pulled out the woofer, drilled the hole in the other box and sprayed the pots. Reassembled. Now three hours, later plugged 'em in and .......... both the tweeter pots work like a charm, but both the midrange pots both had big holes in their sweep - one from - 1 to +1, the other from 0 to +3 (comes back on at wide open). So they work, but not ideally. Turns out I prefer the mids at about -1 anyway, so still functional, but dang, for all that time and effort wouldn't I like 'em to be back to brand new, functionally? When you yank these puppies apart you realize JBL built these things very well and used the highest quality components - you'd think the pots would be a little hardier and less troublesome. Anyway, guess if I want perfection I'll have to pull "em apart again and try to more thoroughly spray out those mid pots. Just need that rare whole afternoon free to get to it. Later, gotmojo

Doc Mark
10-25-2008, 12:55 PM
Hey, gotmojo,

Hummmm, your methods of "how you did it" sort of remind me of OJ's!! Lots of drilling and slicing, and stuff spraying all over the place, until certain things didn't work anymore!!! :blink::blink:;):D Sounds like you had fun messing with it, and that is the most important thing. Take care, and God Bless!

Every Good Wish,
Doc

gotmojo
10-26-2008, 08:41 PM
Hey Doc,

Any suggestions on how to get at those pots in the sealed aluminum boxes? The DeOxit spray seemed to work well on the tweeter pots, but I could actually see what I was doing with those, and they came out working like new. Any suggestions would be appreciated.
Thanks,
gotmojo