JBL LX7 Crossover Restore

[2string]

How do you open up a sealed LX7 crossover so I can replace the caps?. Thanks

[BMWCCA]

How do you open up a sealed LX7 crossover so I can replace the caps?. Thanks

How many threads does it take to ask the same question? ;)

If you have an LX7 crossover, I suppose it'd be easier for you to answer the question—or at least give us a look at the back of the case. Certainly no one who has opened one has seen your last thread, yet, or this one. Maybe you could post a photo for those of us who don't happen to have an LX7 sitting around and then we could all speculate on the how, and perhaps some good might come of it?

[2string]

Moderator please delete this topic...Thanks

[2string]

OK I figured out how to open them Pretty simple and I feel stupid. Does anyone restore these? http://i67.tinypic.com/24delhu.jpg
http://i64.tinypic.com/vwygeg.jpg

http://i65.tinypic.com/24n2ow4.jpg

[Earl K]

Few ( to zero ) active members have the LX7 network ( & apparently even fewer have ever wanted to crack that model open ).

That said, that specific era of ( larger networks ) are typically riveted together.

Once the rivets are drilled out, most of them expose a box full of components that are encased in wax ( though some others might of used tar ).

The wax can be removed ( others before you have done that successfully ) by using a source of constant heat ( like an oven or large stove-top water-filled boiler ).

I've seen pics from members where they have successfully replaced the wax ( paraffin wax, I presume ).

Re-assembly will rely on sheet metal screws ( or rivets, if you own one ).

:)

[2string]

Few ( to zero ) active members have the LX7 network ( & apparently even fewer have ever wanted to crack that model open ).

That said, that specific era of ( larger networks ) are typically riveted together.

Once the rivets are drilled out, most of them expose a box full of components that are encased in wax ( though some others might of used tar ).

The wax can be removed ( others before you have done that successfully ) by using a source of constant heat ( like an oven or large stove-top water-filled boiler ).

I've seen pics from members where they have successfully replaced the wax ( paraffin wax, I presume ).

Re-assembly will rely on sheet metal screws ( or rivets, if you own one ).

:)
I hadn't looked at them in a long time. It has screws that I didn't see. Very easy to open. Looks like tar and it's very hard.

[Joseph Smith Jr]

That's any easy one, you should try one that's been filled to the brim!

Put the potted networks in the freezer for about an hour and the material will chip out fairly easily, done it many times

Disconnect the wiring from the front cover face and level switch first
As the potting material warms up to room temperature while you're working on it things will start to get a little messy (the stuff will start to smear and grub up your hands)
Have some mineral spirits near by and some paper towels

Just prepare your work area and work smart, it's not as bad as it looks

Heating is NOT the way to go, yeah it'll work eventually but 10x the work and clean up
And even in a molten state the stuff will barely pour but for a few seconds and once it's been melted and re-cooled it's an even bigger mess and even more difficult to remove because now it's been reactivated and stuck to warm parts like glue (the factory pour was hot potting material on room temperature parts)

In other words, don't do this with heat even though that's instictively the way to go

You will need several tools, a good ice pick, a small sharp chisel and a flat blade screw driver
Cut gently and hammer lighty, this is not a brute force proposition
If you make your initial cuts in the right places the stuff will come out in nice big chunks, if you study things carefully and make your strikes in the right spots, the entire assembly will pop out of the box which will make things go much faster

Once you start to really expose the components you can break off a lot of it with your fingers
Work slow and carefully and as soon as things start to warm up re-chill the box to keep the tar hard and brittle
After everything's out and in the open and most of the junk's been removed from the assembly you can do a final cosmetic clean up with a heat gun or hair dryer and some mineral spirits

As chunks of the material start to pop out, little slivers will fly around, like chipping a block of ice, so do this in a place where you can clean up easily (like don't do it over a white carpet)

I sit out back on my deck when I do them

Have fun!

Joe

[Earl K]

That's any easy one, you should try one that's been filled to the brim!

Put the potted networks in the freezer for about an hour and the material will chip out fairly easily, done it many times

Disconnect the wiring from the front cover face and level switch first
As the potting material warms up to room temperature while you're working on it things will start to get a little messy (the stuff will start to smear and grub up your hands)
Have some mineral spirits near by and some paper towels

Just prepare your work area and work smart, it's not as bad as it looks

Heating is NOT the way to go, yeah it'll work eventually but 10x the work and clean up
And even in a molten state the stuff will barely pour but for a few seconds and once it's been melted and re-cooled it's an even bigger mess and even more difficult to remove because now it's been reactivated and stuck to warm parts like glue (the factory pour was hot potting material on room temperature parts)

In other words, don't do this with heat even though that's instictively the way to go

You will need several tools, a good ice pick, a small sharp chisel and a flat blade screw driver
Cut gently and hammer lighty, this is not a brute force proposition
If you make your initial cuts in the right places the stuff will come out in nice big chunks, if you study things carefully and make your strikes in the right spots, the entire assembly will pop out of the box which will make things go much faster

Once you start to really expose the components you can break off a lot of it with your fingers
Work slow and carefully and as soon as things start to warm up re-chill the box to keep the tar hard and brittle
After everything's out and in the open and most of the junk's been removed from the assembly you can do a final cosmetic clean up with a heat gun or hair dryer and some mineral spirits

As chunks of the material start to pop out, little slivers will fly around, like chipping a block of ice, so do this in a place where you can clean up easily (like don't do it over a white carpet)

I sit out back on my deck when I do them

Have fun!

Joe


Good Stuff ! ( all that )

:)

[2string]

Thanks for the great help. Good to know these things ahead of time. My local repair guy said, if they are working with no issues to leave them alone. He said there's mostly resistors in them. Will I gain any performance by restoring them?

[Joseph Smith Jr]

Thanks for the great help. Go to know these things ahead of time. My local repair guy said, if they are working with no issues to leave them alone. He said there's mostly resistors in them. Will I gain any performance by restoring them?

OK is there any way to restore a LX7 crossover?

52 views and no help!!! I must be on the wrong forum. Can someone direct me to the right place. Thanks

Moderator please delete this topic...Thanks

Two threads, and an expression of impatience for not receiving an instantaneous answer over a holiday weekend and now this?

So, I have to ask, why did you ask the questions in the first place? But yes, I agree, always good to have a plan. It's also good to know what it is you want to do

Thought you were going to do this work yourself from the way you posed your initial inquiry

Now it sounds like now you are looking for a reason to not put in the effort as work is involved
I'm not into the mechanic A says, mechanic B says speculation opinion game, it's a losing one, so I can't offer much help with that

I know what I would do if they were mine and I had them out and torn down to the point that you have, but that's another story

Sounds like your local repair guy isn't into it unless it has a zipper or buttons (and most vintage gear doesn't)

To answer the new question, yes, you will gain performance and especially so if any of the caps have drifted
For every 4 I change out at least one is off spec enough to make a difference
Whether it's enough to justify the effort to YOUR ears is a question that I can't answer
Only you and God know the answer to that one

Best of luck whatever you decide to, or not to, do

Joe

[2string]

Two threads, and an expression of impatience for not receiving an instantaneous answer over a holiday weekend and now this?

So, I have to ask, why did you ask the questions in the first place? But yes, I agree, always good to have a plan. It's also good to know what it is you want to do

Thought you were going to do this work yourself from the way you posed your initial inquiry

Now it sounds like now you are looking for a reason to not put in the effort as work is involved
I'm not into the mechanic A says, mechanic B says speculation opinion game, it's a losing one, so I can't offer much help with that

I know what I would do if they were mine and I had them out and torn down to the point that you have, but that's another story

Sounds like your local repair guy isn't into it unless it has a zipper or buttons (and most vintage gear doesn't)

To answer the new question, yes, you will gain performance and especially so if any of the caps have drifted
For every 4 I change out at least one is off spec enough to make a difference
Whether it's enough to justify the effort to YOUR ears is a question that I can't answer
Only you and God know the answer to that one

Best of luck whatever you decide to, or not to, do

Joe
The holiday didn't seem to effect the amount of views I had. Anyways Thanks for your help. Just trying to get some advice. Cheers:)
Oh you didn't need to add an extra comment. Just answering my question would have been fine.

[Joseph Smith Jr]

The holiday didn't seem to effect the amount of views I had. Anyways Thanks for your help. Just trying to get some advice. Cheers:)
If advice was all you wanted then that is what you should have asked for, in "General Information"
And maybe, over the Independence Day holiday no one had 20 or 30 minutes they were willing to spend typing to give you specific help and answers to your very specific questions

Joe

[2string]

If advice was all you wanted then that is what you should have asked for, in "General Information"
And maybe, over the Independence Day holiday no one had 20 or 30 minutes they were willing to spend typing to give you specific help and answers to your very specific questions

Joe
Yes sir.. I was wrong I should have waited until after the holiday to get advice. My bad...
edit...3 months a member and you already think you rule the roost! 175 post. You are a busy guy... That averages out to almost 2 post per day.

[BMWCCA]

Oh you didn't need to add an extra comment. Just answering my question would have been fine . . .

Yes sir.. I was wrong I should have waited until after the holiday to get advice. My bad...
edit...3 months a member and you already think you rule the roost! 175 post. You are a busy guy... That averages out to almost 2 post per day.

Wagner is operating currently under the alias "Joe Smith". He's been around for years under the name Thomas Wagner. His treatment of you is simply his normal behavior. Probably why he "left" and re-joined with the current alias. Who knows? :dont-know:

Patience, Tadpole! All in good time.

[2string]

Wagner is operating currently under the alias "Joe Smith". He's been around for years under the name Thomas Wagner. His treatment of you is simply his normal behavior. Probably why he "left" and re-joined with the current alias. Who knows? :dont-know:

Patience, Tadpole! All in good time.
Joe Smith...lol. No problem I can take it. I most likely was a little impatient.

[2string]

If I decide to get these crossovers restored where should I go to do so?

[boputnam]

I've looked - I have no schematics in my files. Odd that one has never come-up while I've been here. Doesn't even search!

Maybe some of the mentors here know better than I do... :dont-know:

[2string]

Click on the link and scroll down you will see it. Is this what your looking for? I was told a long time ago that the black speaker binding post was positive and the red was negative on some older JBL's. Is this true? How do I test it to find out?
http://www.audioheritage.org/vbulletin/showthread.php?6170-Network-Schematics&p=255013#post255013

[grumpy]

Just means cone will pull in with + terminal of a battery on red.
Normal convention now is for the cone to push out. Wiring internal
is usually self consistent with black or black stripe wires going to black terminals.

[2string]

Just means cone will pull in with + terminal of a battery on red.
Normal convention now is for the cone to push out. Wiring internal
is usually self consistent with black or black stripe wires going to black terminals.
So are my C51's designed to pull in or should they push out or does it really matter as long as they both are moving the same way?

[grumpy]

So are my C51's designed to pull in or should they push out or does it really matter as long as they both are moving the same way?

the latter-est. If it still bothers you, then swap +/- on both input terminals, but it has to be both.

[2string]

the latter-est. If it still bothers you, then swap +/- on both input terminals, but it has to be both.
Thanks