Infinity Quantum Midrange repair with pictures !

jt45

Super Member
Here are a few pics of my latest Midrange repair. These are IMO a major
PITA to work on. A few things you might find that come in handy when repairing these.
1. Exacto Knife
2. Very small jewelers screwsriver (flat tip) It comes in very handy cleaning out those channels in the faceplate.
3. Straight pin or needle
4. Magnified Light
5. Soldering Iron with a small tip
6. Meter for testing
7. Good eyes (I kinda failed on this one) or just wing it.

There are 2 methods that I have used to repair these. The first method
is to solder a bridge wire across the break (provided you can find it without
causing another break).
The second method is to remove all the exposed tinsel wire and coating back to the voice coil and use 1 wrap of (Fresh) tinsel wire off of the Voice coil and retrace it back to the solder points of the Connectors.

In these pictures I will be using the second method because I believe it will last longer and doesn't require any tricky bridge wire soldering. Its a tedious job and anyone trying this should practice on a expendable driver before
trying it with a good one.

First up a pic of the victim (tested open)

IMG_1756.JPG


The first thing I do is remove all the old Tinsel Wire and coating from the Solder points back to the dome. I use the exacto knife and the jewelers screwdriver for this part.

IMG_1758.JPG


IMG_1759.JPG


Then remove the 4 faceplace screws (be sure to mark the position of the Faceplate/Dome in relation to the Magnet). Take off the faceplate and flip it over, you should be able to see the voice coil with the tinsel wire wrapped.
At this point I go ahead remove the Glued parts of old tinsel wire on the backside of the dome. (Its not easy to seperate it from the cloth dome)

IMG_1762.JPG

IMG_1764.JPG


This is the part where it gets tricky, I usually use a pin or needle to open
a tiny channel right where it runs between the dome and Voice coil (use caution here because if you punch through too hard you can damage the voice coil (bend it). Now I slowly pull 1 wrap off the coil and retrace it back thru the hole I made with the needle to the inside of the dome. I use one wrap from the top and one wrap from the bottom of the Tinsel wire.

IMG_1768.JPG


IMG_1769.JPG


Thread the tinsel wire back through the dome, at this point I add a dab of glue inside the dome like the original wire had to secure it to the cloth and let that dry before moving on to the next step.

Then I cut off the tinsel wire at the right length to make the solder point but still provide room for the wire to move. Before soldering you MUST scrape off
the coating on the tinsel wire or you wont get a reading.

IMG_1771.JPG


Notice how the last 1/4 inch is copper and not red like the coating.

IMG_1772.JPG


I used a black adhesive that dries tacky to coat the wire and seal the channel, Im still searching for the right type of glue or silicone and a smaller
method of applying it. Maybe a syringe type applicator with a small tip ! I know this would be helpfull in making a neater job.

Here is the final pics of the working driver. I usually get a slightly lower reading on the meter from 7.2 down to 6.9 ohms seems to be the norm
when using those new tinsel wire wraps from the voice coil. I cannot hear a difference in their performance though.

IMG_1774.JPG


IMG_1775.JPG


Hope this helps someone !

JT
 
Yeah, that's really nice! I sent mine to someone a while back to get a few leads repaired. I never realized how painstaking that repair is. It's definitely a driver well worth the repair effort though. Most of all, you must be extra patient to take the time to photo document your efforts! Well done! :tresbon:
 
I really liked you post to, as I repairs all of my mid domes on a pair of QLS=1's that I purchased. Unlike your post I cleaned the varnish off the tinsle wire on the back of the dome which was a real pain to get the varnish off and tin the wire since it was glued to the back of the dome, two of them I was unable to get any good wire to tin, I replaced them with some other spares I had purchased. Now that I see how you pulled a wrap of the voice coil I can probably repair them, I am glad I didn't trash them. What I found very useful was one of those jewelers magnifying lenses on an arm with a floresent lamp around it. It frees up your hands and makes seeing the wires much easier. Funny some guy who was moving had given me a bunch of stuff out of his home and garage and that light was one of the items, I had been using it for my stamp collecting but it was great for repairing those speakers.
 
Hi Ken, I have one of those tall lighted magnifier's here on my desk and couldn't get by without it, I also use my reading glasses, even so, those tinsel wires are hard to see and work with. Im not a patient person so I usually put on some Keiko Matsui for background music to help keep me focused and slow me down some.:D
 
As usual very nice pics, JT. You can also pull just enough voice coil wire without removing a full "revolution". It's wonderful to be able to repair these mids!
 
Hey all - Been a while since I last checked in.

I just picked up a pair of Quantum 5's that I'd like to restore. Seems the value is there.

Thanks for this thread. Great info and pictorial!
 
JT45

I used a modified approach to yours and so far the results are good. One one side of the dome, I bridged the existing tinsels with solder. There was enough material there to work with. I found that using a soldering iron on the OEM glue turns it brittle and makes it easier to flake away with an Exacto knife.

On the other half of the dome, I used your approach, cut the tinsel at the base of the VC, unwound 1 turn, and then used a sewing needle and thread to weave the tinsel back under the dome and out again. The needle punctured the alum VC sleeve very high up, almost in line with the OEM cut out. I'm hoping it's high enough up that the VC won't hit the bump stop on the magnet assembly.

I tested for continuity and have about 7 ohm across the terminals. Sweet!

I too, am experimenting with the right adhesive. I set aside a dab of automotive gasket sealer. My thoughts are that it sets hard enough to seal fluids, but soft enough to allow auto parts to be disassembled without damage. I also tried a 2-part resin epoxy. Not sure if it will be too rigid. The third option is some kind of rubber cement.

Macro pictures akin to JT45's coming tomorrow....
 
I've got two midranges down on my Quantum 2's that I need to repair as well. I like this approach the best of what I have read. Any tips on the soldering part? That wire is pretty thin.
 
The bridge connection wasn't that bad. The hardest part was making sure I didn't damage the tinsel wire under the plastic coating. But like I said above, heating the coating caused it to become brittle and flake off the wire (I expected it to melt, but didn't). Once the coating is gone, it's just making sure you have a hot gun and not too much solder. You don't want to heat the VC wire too much or risk fusing it together around the VC, essentially that would "short circuit" the coil and render the speaker useless.
 
Pictures as promised. I decided to use the same glue/sealant that came with the woofer refoam kit. It dries clear, but is strong, flexible and non-conductive. I applied the glue with a hobby brush. Did 2 coats to get the desired coating.

Bridge connection
7501663982_78742beb7b_c.jpg


Tinsel repair on other side. Nothing to work with.
7501663260_c298c0436c_c.jpg


Poked through VC with needle. smoothed the hole over with small pliers and then coated the wire with glue/sealant.
7501662930_37b7d7cc4f_c.jpg


Tinsel coming out of dome. I didn't want to push through in the same exact location as OEM because the old glue was too strong and I was worried my hand would slip and rip through the fabric.
7501661886_9bb467e08b_c.jpg


Testing continuity before the final assembly.
7501661486_993d3f3e81_c.jpg


Final shaping of the tinsel. Glue came next. Need to d/l those photos.
7501660410_71beb58fc0_c.jpg


Incidentally, the hardest part of this job was being sure the VC lined up with the magnet assembly and then being confident that everything was in place before inserting the 4 screws. I did this by hooking the dome up directly to the stereo and listening for abnormalities in the sound. There's about 1-2mm of room in any direction. I am fairly certain I lined it up. I relied on the same technique as the woofer repair, let the magnetic field to most of the work and assume the speaker would set itself.
 
Update! The Tech called and said he was able to find some voice coils locally so I will be able to pick them up today get them installed and rock out somthin' serious tonight!
 
My experience

I also had to repair one of my mid range drivers on my Infinity Quantum Jr. The bridge wire had disintegrated and fallen off on one of the connections. I took pictures but my photo skills are not as fancy nor do I have a nice macro lens for the closeups.

My procedure was the same as above but with these modifications:

- Once the magnet is taken apart and the channel on the housing craped clean, I scraped down the glue on the underside of the dome until the voice coil wire was revealed just before it passes through the dome. Then I scraped some more until it had a segment of bare copper.

- A hole was poked with a needle as stated previously about where the original wire passes through the dome.

- I salvaged a dead computer fan and took some of the winding from one of it's electromagnets as the wire was about the proper gauge and coated. I stripped the coating off one end and threaded it through the dome from front to back.

- The stripped end of the new wire was lightly tinned, but not with dobs and dobs of solder. I didn't want to effect the moving mass too much.

- I then attached the new wire to the exposed copper of the old voice coil wire on the back of the dome, checked continuity and sealed with glue.

The rest of the procedure is the same as above. If I were to do this again I'd want to find a better way to line up the voice coil in the magnet. I'm still not completely sure it's correctly aligned.

IMG_20130818_101921.jpg


IMG_20130818_101931.jpg


You can see the new wire soldered to the old voice coil wire on the bottom of the picture.
IMG_20130818_115202.jpg


IMG_20130818_121107.jpg


IMG_20130819_083513.jpg


IMG_20130819_083409.jpg
 
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they really should have put dimples on the faceplate to line the VC up properly.

you'll hear if the VC is not lined up. try a midrange tone test. you can find them on YouTube.
 
Dude you are Awesome! I have been looking for some of them on ebay because of the problem you just described.

Thank you! Hell, I will be the first to offer you a beer on me if I am ever in the area.
 
Thanks a ton!

Here are a few pics of my latest Midrange repair. These are IMO a major
PITA to work on. A few things you might find that come in handy when repairing these.
1. Exacto Knife
2. Very small jewelers screwsriver (flat tip) It comes in very handy cleaning out those channels in the faceplate.
3. Straight pin or needle
4. Magnified Light
5. Soldering Iron with a small tip
6. Meter for testing
7. Good eyes (I kinda failed on this one) or just wing it.

There are 2 methods that I have used to repair these. The first method
is to solder a bridge wire across the break (provided you can find it without
causing another break).
The second method is to remove all the exposed tinsel wire and coating back to the voice coil and use 1 wrap of (Fresh) tinsel wire off of the Voice coil and retrace it back to the solder points of the Connectors.

In these pictures I will be using the second method because I believe it will last longer and doesn't require any tricky bridge wire soldering. Its a tedious job and anyone trying this should practice on a expendable driver before
trying it with a good one.

First up a pic of the victim (tested open)

IMG_1756.JPG


The first thing I do is remove all the old Tinsel Wire and coating from the Solder points back to the dome. I use the exacto knife and the jewelers screwdriver for this part.

IMG_1758.JPG


IMG_1759.JPG


Then remove the 4 faceplace screws (be sure to mark the position of the Faceplate/Dome in relation to the Magnet). Take off the faceplate and flip it over, you should be able to see the voice coil with the tinsel wire wrapped.
At this point I go ahead remove the Glued parts of old tinsel wire on the backside of the dome. (Its not easy to seperate it from the cloth dome)

IMG_1762.JPG

IMG_1764.JPG


This is the part where it gets tricky, I usually use a pin or needle to open
a tiny channel right where it runs between the dome and Voice coil (use caution here because if you punch through too hard you can damage the voice coil (bend it). Now I slowly pull 1 wrap off the coil and retrace it back thru the hole I made with the needle to the inside of the dome. I use one wrap from the top and one wrap from the bottom of the Tinsel wire.

IMG_1768.JPG


IMG_1769.JPG


Thread the tinsel wire back through the dome, at this point I add a dab of glue inside the dome like the original wire had to secure it to the cloth and let that dry before moving on to the next step.

Then I cut off the tinsel wire at the right length to make the solder point but still provide room for the wire to move. Before soldering you MUST scrape off
the coating on the tinsel wire or you wont get a reading.

IMG_1771.JPG


Notice how the last 1/4 inch is copper and not red like the coating.

IMG_1772.JPG


I used a black adhesive that dries tacky to coat the wire and seal the channel, Im still searching for the right type of glue or silicone and a smaller
method of applying it. Maybe a syringe type applicator with a small tip ! I know this would be helpfull in making a neater job.

Here is the final pics of the working driver. I usually get a slightly lower reading on the meter from 7.2 down to 6.9 ohms seems to be the norm
when using those new tinsel wire wraps from the voice coil. I cannot hear a difference in their performance though.

IMG_1774.JPG


IMG_1775.JPG


Hope this helps someone !

JT

Did one successfully and am 2/3 of the way done with the second midrange
 
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