JBL 035Ti repair

[spirou38]

Hi JBL lovers,

Yesterday I received a nice pair of JBL L80T.
But the 035Ti has lost its magnet during the trip :crying:
Fortunately there was no damage on the woofer cone.
Is it possible to reglue it ? It seems very difficult to center it :(
If it is possible, which kind of glue have I to use ?
Thank you for your help.

Pascal

[Frenchie]

Faut un générateur pour le centrer ; le 035TIA a des picots de centrage pour éviter ça.
Pourquoi l'aimant est tombé au fait ? Si les vis sont cassées… :blink:

[jbl_daddy]

I melted one of mine down in my L100t's about three months ago, ebay is your friend for 80 euros you will have a pair of tweeters with one for the next time one goes south.

Mark

[Ralph856]

Same thing happened to me recently. Received a pair of L20t's, which had not been packed well by their seller, and one of the 035Ti's had its magnet broken away. Seems to be a bit of a pattern with this tweeter:hmm:.

Look out for replacements on ebay. I luckily picked one up for only £20 but they usually go for over £50, incl shipping, or more for a pair. Alternately, buy an appropriate second-hand, local pickup, JBL speaker going cheap that already has the 035Ti (or 035TiA) in it. It could be more cost effective than hunting down parted out tweeters. I've seen some 035Ti-equipped speakers going for under £100 (such as a pair of L80T recently)

[spirou38]

Faut un générateur pour le centrer ; le 035TIA a des picots de centrage pour éviter ça.
Pourquoi l'aimant est tombé au fait ? Si les vis sont cassées… :blink:

L'aimant est tombé au cours du transport, ce malgré un super emballage. Il y a trace de choc sur l'emballage mais visible que de l'intérieur de celui-ci !

[spirou38]

Same thing happened to me recently. Received a pair of L20t's, which had not been packed well by their seller, and one of the 035Ti's had its magnet broken away. Seems to be a bit of a pattern with this tweeter:hmm:.

Look out for replacements on ebay. I luckily picked one up for only £20 but they usually go for over £50, incl shipping, or more for a pair. Alternately, buy an appropriate second-hand, local pickup, JBL speaker going cheap that already has the 035Ti (or 035TiA) in it. It could be more cost effective than hunting down parted out tweeters. I've seen some 035Ti-equipped speakers going for under £100 (such as a pair of L80T recently)

Unfortunately I live in France and I'm afraid that it will occur the same problem in transportation if I find 035Ti's on eBay.

[spirou38]

Same thing happened to me recently. Received a pair of L20t's, which had not been packed well by their seller, and one of the 035Ti's had its magnet broken away. Seems to be a bit of a pattern with this tweeter:hmm:.

Look out for replacements on ebay. I luckily picked one up for only £20 but they usually go for over £50, incl shipping, or more for a pair. Alternately, buy an appropriate second-hand, local pickup, JBL speaker going cheap that already has the 035Ti (or 035TiA) in it. It could be more cost effective than hunting down parted out tweeters. I've seen some 035Ti-equipped speakers going for under £100 (such as a pair of L80T recently)


I melted one of mine down in my L100t's about three months ago, ebay is your friend for 80 euros you will have a pair of tweeters with one for the next time one goes south.

Mark

Unfortunately I live in France and I'm afraid that it will occur the same problem in transportation if I find 035Ti's on eBay.

[Ralph856]

A tweeter on its own shouldn't break in transit, as long as its wrapped well with bubblewrap etc. Just make sure it's sent insured, if you are worried.

[ratitifb]

A tweeter on its own shouldn't break in transit, as long as its wrapped well with bubblewrap etc. Just make sure it's sent insured, if you are worried.and ... double boxed plus foam ;) with metal grill/dome protection (cardboard tube for example).
Several pairs got home by airmail from USA to France without any damage during overseas shipping :p

[Ralph856]

Someone recently sent me a pair of 035ti's in a small box with not that much bubblewrap and they arrived safely. I think they are far more likely to get damaged while inside a speaker that isn't packed well than on their own.

[spirou38]

and ... double boxed plus foam ;) with metal grill/dome protection (cardboard tube for example).
Several pairs got home by airmail from USA to France without any damage during overseas shipping :p


Someone recently sent me a pair of 035ti's in a small box with not that much bubblewrap and they arrived safely. I think they are far more likely to get damaged while inside a speaker that isn't packed well than on their own.

The L80T were profesionnaly packed ... but carrying was achieved by GLS

[Slare]

My memory might be wrong, but I thought the magnet assembly tied to the diaphragm assembly (front plate, dome, voice coil) with three small allen head screws. It's self-aligning assuming the diaphragm/voice coil wasn't damaged when the magnet fell off.

I think it's very unlikely that the motor would fall off without damage (usually the mounting plate breaks) but I suppose if the screws work themselves loose, it's possible.

Am I wrong?

[spirou38]

My memory might be wrong, but I thought the magnet assembly tied to the diaphragm assembly (front plate, dome, voice coil) with three small allen head screws. It's self-aligning assuming the diaphragm/voice coil wasn't damaged when the magnet fell off.

I think it's very unlikely that the motor would fall off without damage (usually the mounting plate breaks) but I suppose if the screws work themselves loose, it's possible.

Am I wrong?

Unfortunately, no self-aligning srcews :( just glue.

But when falling off the 035Ti, it made just a little chip in the paint of the L80T bass speaker, fortunately no damage on the woofer cone.

[Slare]

Well, I think that's the problem then. It shouldn't have been glued. There are four bolts that hold the motor to the diaphragm. The arrows show where these bolts bolt into the magnet assembly.

Maybe there were glued versions but I've never seen or heard of one as such.

Does yours look different?

[jbl_daddy]

Is there a person that has a picture of one with the engine broke off? I am going to take apart my burnt up one tonight and look for glue...

[spirou38]

Well, I think that's the problem then. It shouldn't have been glued. There are four bolts that hold the motor to the diaphragm. The arrows show where these bolts bolt into the magnet assembly.

Maybe there were glued versions but I've never seen or heard of one as such.

Does yours look different?

No, my one doesn't look different ... but have a look to the following picture and you will see that there are 2 metal parts : the one with the 4 screw holes should be glued on the magnet itself. Note that you can see the glue marks on both metal parts. Of course the metal part that is attached to the plastic diaphragm part is not glued on the plastic.

...


Is there a person that has a picture of one with the engine broke off? I am going to take apart my burnt up one tonight and look for glue...

Here it is

...

[BMWCCA]

Are those your L80Ts?

Are they black?

:hmm:

[mech986]

Ahh, the front plate with attached dome/voice coil screws down to the top plate which is glued to the magnet which is glued to the pole piece/back plate. What happened is the magnet came unglued from the top plate which is still screwed to the front plate.

Somehow can't imagine the voice coil is still round with the pole piece falling out unless the pole piece fell straight back with the speaker on its back (like if the package was dropped). But typically there needs to be a shear force at 90 degrees to break the glue?

Looks a lot like one of Scotty's drivers that lost its magnet.

[spirou38]

Are those your L80Ts?

Are they black?

:hmm:

Yes they arrived last week and as you can see, they are black :p.

When I was young the L80T were my first JBL speakers. I bought those for my grandson who is 10 years old. He must know what are JBL speakers.

A few hours ago I won a couple of 035TiA on eBay. They will replace both 035Ti ;) .

But I will repair the 035Ti : I will try to find a non metallic pipe of appropriate diameter for centering and gluing the to metal parts. Then just put the diaph in the centering pins and 4 screws.

[spirou38]

Ahh, the front plate with attached dome/voice coil screws down to the top plate which is glued to the magnet which is glued to the pole piece/back plate. What happened is the magnet came unglued from the top plate which is still screwed to the front plate.

Somehow can't imagine the voice coil is still round with the pole piece falling out unless the pole piece fell straight back with the speaker on its back (like if the package was dropped). But typically there needs to be a shear force at 90 degrees to break the glue?

Looks a lot like one of Scotty's drivers that lost its magnet.

Yes mech986, I think you are right :applaud:: some marks inside the packing show that the L80T fall on its back. And it seems that the shock was violent. Fortunately the packing was very good and there is no other damage than the 035Ti and the voice coil is still round and perfect ; I measured it with a digital "pied a coulisse" - I don't know the English word but I included a picture hereafter.

...

[pos]

Are those your L80Ts?

Are they black?

:hmm:

There is a "lacqueur" serie that is black:
http://lansingheritage.org/html/jbl/specs/home-speakers/1987-lacqueur.htm

But I think the one Spirou has is a L80T GI that shows up often on ebay Germany. It is mat black.

[spirou38]

There is a "lacqueur" serie that is black:
http://lansingheritage.org/html/jbl/specs/home-speakers/1987-lacqueur.htm

But I think the one Spirou has is a L80T GI that shows up often on ebay Germany. It is mat black.

you are right :applaud:my L80T GI come from Germany

[ratitifb]

But I will repair the 035Ti only hoping you are able to well centering all parts with magnetized motor :cool: and there will be no irreversible magnetic losses due to "air gap re-gluing" and/or reluctance change ;)

[BMWCCA]

I think the one Spirou has is a L80T GI that shows up often on ebay Germany. It is mat black.Appears to have a finish similar to the L7 and that series. Seawolf's favorite "black ash". :D

Interesting. I've seen the lacquer "BQ" series brochure in the library but never a matte-black version. Spirou, more pictures when you get them back together? Thanks. :applaud:

Hmm. I'd buy these: http://www.marktplaats.nl/index.php?url=http%3A//audio-tv-foto.marktplaats.nl/luidsprekers/260095260-jbl-l80t-gi-speakers.html

Another pair here: See if this link still works: http://74.125.47.132/search?q=cache:giAJfKtj22MJ:teszvesz.hu/item614741609_jbl_l80t_gi_2x150w_usa.html+jbl+l80t +gi&cd=8&hl=en&ct=clnk&gl=us

If not, maybe these will hang around:

http://img21.imageshack.us/img21/9150/jbl01.jpg

http://img21.imageshack.us/img21/6566/jbl07.jpg

http://img21.imageshack.us/img21/1415/jbl09.jpg

[spirou38]

Appears to have a finish similar to the L7 and that series. Seawolf's favorite "black ash". :D

Interesting. I've seen the lacquer "BQ" series brochure in the library but never a matte-black version. Spirou, more pictures when you get them back together? Thanks. :applaud:

Hmm. I'd buy these: http://www.marktplaats.nl/index.php?url=http%3A//audio-tv-foto.marktplaats.nl/luidsprekers/260095260-jbl-l80t-gi-speakers.html

Another pair here: See if this link still works: http://74.125.47.132/search?q=cache:giAJfKtj22MJ:teszvesz.hu/item614741609_jbl_l80t_gi_2x150w_usa.html+jbl+l80t +gi&cd=8&hl=en&ct=clnk&gl=us

If not, maybe these will hang around:



My L80T GI seem to be in a better shape except for one tweeter.

I will put some pics when I will receive the 035TiA.

[spirou38]

Looks a lot like one of Scotty's drivers that lost its magnet.



Hi everybody,

Good new :D Yesterday I tried to repair the 035Ti.

First of all, I took some measurements and found that the diameter difference between the "cylinder" that is centered in the magnet ( called polar part ??? ) and that goes in the hole of the ring ( that was unglued from the magnet ) and the hole of the ring was exactly 1.6 mm.

So I looked after some 0.8 mm non magnetic parts and found some plastic that was exactly 0.8 mm thick. I cut four 16 mm wide parts . Those plastic parts can easyly be bent.

Then I inserted the 4 plastic parts between the magnet and the cylinder inside the magnet, put some cyanoacrylique glue on the magnet ( taking care that there will not be some glue in the centering holes and screw holes of the ring when gluing the ring ), and put the ring that because of the plastic parts automatically centered itself.

Of course I first tried without glue !

I waited 24 hours so that the glue could dry. Then carefully mounted the diaphragm and put the 035Ti in the L80T.

Great sounding, no difference between the good one and the repaired one, no rubbing coil sound :). I hope that will last for a long time ...

Unfortunately I forgot taking pictures. I hope you could understand the process.

Here is a picture of that kind of plastic parts :

If somebody needs of some of those plastic parts for repairing a 035Ti ( Scotty ??? ), I can supply some.

[ratitifb]

Actually you applied the shim method to center the voice coil with four pieces of plastic of suitable thickness. ;)

"no difference between the good one and the repaired one" : could you confirm by measuring their respective efficiency ?

[spirou38]

Actually you applied the shim method to center the voice coil with four pieces of plastic of suitable thickness. ;)

"no difference between the good one and the repaired one" : could you confirm by measuring their respective efficiency ?

For checking voice coil centering I checked with stainless steel special blades and the error was less than 5/100 millimeter but more than 1/100 :D.

Then I made tests playing cd in mono mode with both speakers very close then very distant . Couldn't notice any difference.

For the moment I have not a lot of time for measuring ; in the following weeks perhaps I will have time to move my Tact digital préamp and Earthworks measurement mike to make response curve and efficiency measurements.

[Earl K]

Good new :D Yesterday I tried to repair the 035Ti.

Pascal, I'm very impressed when someone executes a successful repair such as you have . Good Show ! :thmbsup:


I was equally as impressed when RobH fixed a 2435h that he dropped ( it's ironic what sticks in my brain , ha ! )



First of all, I took some measurements and found that the diameter difference between the "cylinder" that is centered in the magnet ( called polar part ??? ) and that goes in the hole of the ring ( that was unglued from the magnet ) and the hole of the ring was exactly 1.6 mm.

So I looked after some 0.8 mm non magnetic parts and found some plastic that was exactly 0.8 mm thick. I cut four 16 mm wide parts . Those plastic parts can easyly be bent.

Then I inserted the 4 plastic parts between the magnet and the cylinder inside the magnet, put some cyanoacrylique glue on the magnet ( taking care that there will not be some glue in the centering holes and screw holes of the ring when gluing the ring ), and put the ring that because of the plastic parts automatically centered itself.

Of course I first tried without glue !

I waited 24 hours so that the glue could dry. Then carefully mounted the diaphragm and put the 035Ti in the L80T.

Great sounding, no difference between the good one and the repaired one, no rubbing coil sound :). I hope that will last for a long time ...

Thanks for the "schooling" on the method ! ;)


,,,,,,snip,,,,,, in the following weeks perhaps I will have time to move my Tact digital préamp and Earthworks measurement mike to make response curve and efficiency measurements.

- At the bottom is the response for one of my 035Ti(s) . This was taken a few months back . It was either 20 or 25 degrees off-axis .

- Previous to these ARTA measurements, just listening to the "crest-factor" of pink noise being run through this tweet led me to the conclusion that it was a nice tweeter .
- My CSD would seem to support that view .

http://www.audioheritage.org/photopost/data//500/JBL_035Ti_1_5uF_25_deg_off-axis_CSD_.png

>< cheers :)

[mech986]

Spirou: Great job on the repair. Excellent engineering of the solution, and certainly a good technique. For your information, the tool you pictured is called a Vernier Caliper and it is very handy to have.

See this reference:
http://en.wikipedia.org/wiki/Caliper


EarlK: That waterfall plot is great. What software and measurement system are you using? Do you have plots which extend the Frequency (X-axis) marking back to the Zero time mark so that it is easier to see where the resonance ripples and troughs are located?

You learn something new here at LH everyday!!

Regards,

Bart

[Earl K]

EarlK: That waterfall plot is great. What software and measurement system are you using?

- You're looking at some results as captured and dispalyed by ARTA . (http://www.fesb.hr/~mateljan/arta/)

- Author of this software is : Ivo Mateljan (http://www.fesb.hr/~mateljan/), Electroacoustic Laboratory, Faculty of Electrical Engineering, 21000 Split, Croatia.

- Download his shareware Here ! (http://www.fesb.hr/~mateljan/arta/download.htm)

- I use an M-Audio USB card. This is it ( it has more input channels than necessary / most people should look at the Fast Track Pro instead ) >
http://www.fullcompass.com/common/products/original/45209.jpg (http://www.fullcompass.com/product/348066.html)
- My test mic is this Audix TR40. >
http://www.fullcompass.com/common/products/original/66767.jpg (http://www.fullcompass.com/product/277714.html)


Do you have plots which extend the Frequency (X-axis) marking back to the Zero time mark so that it is easier to see where the resonance ripples and troughs are located?

- Sorry , but I don't have that file saved ( so, I have no ability to reprocess without retesting ) .

- I agree that these semi 3D perspective makes it quite hard to precisely connect a frequency to "some big bulge in the color" .

- It's easier to make the connection using the "sonogram" layout which is 2D ( and makes no bones about it ) .


>< cheers :)

[spirou38]

Pascal, I'm very impressed when someone executes a successful repair such as you have . Good Show ! :thmbsup:

Hello Earl K,

... But it should have been better with some pictures :( ...


- At the bottom is the response for one of my 035Ti(s) . This was taken a few months back . It was either 20 or 25 degrees off-axis .

- Previous to these ARTA measurements, just listening to the "crest-factor" of pink noise being run through this tweet led me to the conclusion that it was a nice tweeter .
- My CSD would seem to support that view .

http://www.audioheritage.org/photopost/data//500/JBL_035Ti_1_5uF_25_deg_off-axis_CSD_.png

>< cheers :)

ARTA seems very interesting.
I think I will soon try but I should have to enter my Earthworks M30BX mike calibration file first.
Here is a scan of the response curve on the Earthworks document :
I have 2 files on a CD : a .TXT and a .MIC.
Here are the beginning and the end of the .TXT and the .MIC files converted in .doc. The .MIC was specially made for the TACT RCS 2.2 digital preamp.


Sorry but I never succeed in inserting the pics and links where they should be :(

[spirou38]

Spirou: Great job on the repair. Excellent engineering of the solution, and certainly a good technique. For your information, the tool you pictured is called a Vernier Caliper and it is very handy to have.

See this reference:
http://en.wikipedia.org/wiki/Caliper



Hello Mech986,

Thank you for the free English lesson :applaud::D .

My 2 vernier calipers were very helpful for the repair but one of them was very dificult to use because it is not made of a good stainless steel :banghead: