Saturday, March 12, 2016

Logitech Squeezebox Boom / UE Radio Bass Woofer Repair

[Update 2016-06-14]
A new blog entry describes the VFD display replacement procedure (another popular Boom issue). See here if you are interested: Repair Guide

Logitech Squeezebox Boom / UE Radio Bass Woofer Repair

Hi everyone,

if you have ever experienced a Squeezebox Boom in action, it is likely you just wanted one of them. I cannot remember any other device that produces this stunning sound from such a small case. It's pretty good with low volume but also loud enough to run a mid-sized party. After about 10 years, many Boom owners find that the bass gets distorted. The probability of this happening gets higher when the units are turned up loud for longer periods of time.
This is commonly known as the "farting bass" syndrome. The bass is overlaid with some clicking or slapping noise in sync with the low frequencies being played back. It can be heard with any kind of music but a clean signal exposes the problem best. Therefore I have prepared some OGG samples for you. Just right-click and select "Download" in your browser:



Here are some screenshots from Audacity where I created the samples:
left-only
right-only
both channels
Opening the resulting OGGs reveals that only one channel is affected in the respective files:
left-only, resulting OGG waveform
right-only, resulting OGG waveform
These samples are a practically lossless representation (OGG quality level 9 of 10) of a 30 or 50Hz sine wave. Each is 30 seconds long featuring a clean sine wave of 30 or 50Hz which fades in within 2 seconds at the start, and fades out 2 seconds towards the end. Each second, a "tick" signal is included. It is supposed to help you guess the volume. 
As it might be hard to locate sounds at frequencies this deep, I have also provided samples which are silent on one channel. So if you play the "only left" or "only right" samples, and get distortions, you know for sure which is the faulty channel.

EDIT 2017-04-25: I reduced the volume of the tick channel, it was just too loud. I also found that a Boom apparently never plays one channel solo. The "only left" and "only right" OGG files are clean as can be seen in the screenshots above. Despite that, the Boom is moving both woofers at all times. I think the explanation is that if one woofer is moving, it is also moving air inside the air-tight Boom's body, and creating pressure differences. The other woofer may move just as a result without being actively driven as it is the only point where the pressure difference can be equalized. So imagine the left woofer moves outward. This reduces pressure inside the Boom body. As a result, the right woofer is being pulled in, just from the negative pressure.
This effect will also cause the stereo samples to fail because both woofers are driven simultaneously so the basically cancel each other out. The result is that both are trying to create the same pressure differential. Both moving outward will cause the internal "vacuum" to keep them from freely doing so, and likewise both moving inward will stop them after a bit because of the internal pressure peak.
It's an interesting matter, and pretty sure the SlimDevices engineers had to take it into account in their DSP design.

So testing with these samples is not 100% accurate unless you remove the speaker faceplate from the back side of the housing. Only then will both woofers be able to move completely unaffected by each other.
So the best way to point out defective woofers is putting your face next to the Boom, nose next to the knob, for the best possible separation, playing the left-only or right-only files, and in each case carefully listening to both sides. It gets easier and safer only when you disassemble the housing as shown below.


While the 30Hz sample should be practically inaudible, the 50Hz is in a range that everybody should be capable of perceiving. What you should hear is either nothing or just a very low single frequency. What you should not hear is any additional hum, high-pitch sound, flutter or whatever. If you do, welcome to the club.

To verify that the correct channel is playing, you may also consider removing the speaker grilles (see disassembly instructions below), and take a close look at the bass woofers or slightly touch them - no force there, please! Best use the back of a finger and just ever so slightly get close enough. You should feel the vibration at the woofer that is playing, and feel nothing at the one on the other side. When a woofer is playing the sample, it should also move visibly, the cone becoming "blurry".

This image shows a defective unit. At first glance it is hard to see anything wrong there, and it's even harder to see if the woofer is mounted:


We get a little closer and you may see the fissure now:


When the woofer is still in place, most of its outer ring is covered by a plastic surround of the Boom case. What you may see then on close inspection is that the shape of the speaker surround is not even. It arches more (or appears less flat) in areas where the lateral support is missing.
This is where the bass cone and the surround are no longer moving in a controlled manner. Where the surround is cracked, the edges that face each other are touching as a result of the speaker cone vibration, creating the additional noise.
Don't even consider applying just a bit of glue here to fix it. There is too much motion so either the glue won't hold at all, or if it is powerful enough, its chemical aggressivity will harden the surround and make things even worse. Forget about even the softest and toughest sort of adhesive tape. Bear in mind that this surround is the connecting element between the highly mobile bass cone and the rock-solid metal cage. So there is a lot of motion involved and I cannot imagine any way to fix a weakened material without causing undesired impact on its physical properties, and eventually the sound. Really, there is no other way than a full-scale replacement of the surround, or the entire speaker.

Now everybody knows that Boom units are getting rare, and spare parts even more so. Many used Booms at eBay have defective woofers but it is rarely ever mentioned. Many are sold as 100% intact, or have defects of other sorts, and many people don't even know there is something wrong. Those who didn't hear an intact Boom before might assume that's all normal. For those who really care, here is a guide on how to repair your Boom speakers.

Depending on where you live, it may be hard to get hold of the parts that I am referring to here. If that's the case, feel free to ask me, I may jump in as a "proxy" if I can.
There are actually two ways for you to solve the problem. You may replace the entire woofer with a new one (or a used one in better shape). That is the rather easy but more expensive approach, and probably not possible for long anymore because the world is running out of suppliers. Then there are repair kits available to fix broken speakers in a DIY fashion. That's what this guide is mainly about.

Tools Needed

What you need for this repair is:

  • a T10 torx screwdriver (shaft length > 4cm is recommended). Use one with a big grip for good torque. You will need that for undoing the eight screws that hold the case together. They are so tight that one might believe they were fixed when the case was still hot from the mold
  • a spudger or flat but stable piece of plastic to get off the grilles
  • straight pliers
  • a stronger sewing needle to remove glue from the screws that hold the bass woofers in place. You need to do this in order to make the screws operable again. They are soaked up in hardened glue so much that the torx screwdriver will not lock
  • lots and lots and lots and lots of patience
If you do the advanced repair, you will also need:
  • a pair of nail scissors (or any other sort of precision scissors)
  • a rasp to remove glue remains
  • a blade, knife, or a scalpel (for the brave)
  • replacement speaker foam surround for each defective woofer
  • repair glue

How to Get to the Speakers - Boom Disassembly

You will have to disassemble your Boom pretty far to change the speakers in any case. It is not possible to fix them from the outside. So what you need to do is:
  1. remove the speaker grilles (left and right)
  2. unscrew the control panel, four T10 torx screws (one in each corner)
  3. pull the control panel flat flex cable
  4. unscrew the mainboard, five T10 torx screws (one in each corner and one in the center)
  5. pull the mainboard out, thereby undoing the speaker connector
  6. unscrew the front half of the case, eight T10 torx screws
  7. pull the front piece of the case out
  8. remove glue from the four torx screws that hold each bass woofer
  9. unplug and unscrew the woofer(s) in question, four T10 torx screws each

Disassembly: Remove the Speaker Grilles

The grilles are attached to the case with rubber-covered tabs. I recommend using a flat spudger that can be pushed in between the outer case rim and the grille. Take care here because the outer case rim is plastic so it is very delicate. You may easily leave marks there that look ugly ever after. So be very gentle and take your time.

Once we're in, lift the grille a bit but do not try to remove it completely yet. Do not use the case rim to crank the grille away because that might ruin the look.


The same needs to be done on the other end. There are also fixing tabs on the outer edge of each grille but they will give way once the upper and lower edge are free.


Eventually this is what you see:

Disassembly: Loosen Control Panel

Next level: let's undo the control panel because it is in the way later. First undo these four TX10 screws:


Disassembly: Undo Control Panel Flat Flex and Remove Control Panel

Once the control panel is loose, be aware that there is a short flat flex ribbon cable in the bottom right corner that needs to be loosened on one of its ends. I find it easier to remove the mainboard-side end of it. This is what you will see when you lift the control panel (gently!)


Just grab the flat flex cable and pull it away from the connector. This should not be done more often than absolutely necessary because the blade contacts in the connector begin to damage the cable contacts after about five times unplugging and reconnecting. You may end with a broken flat flex, and these things are close to unobtanium.

Disassembly: Remove Mainboard

With the control panel gone, we see the mainboard in all its glory:


Loosen five TX10 screws in these positions. They are the same length as the four we have already removed earlier. Keep in mind the positions and orientation of the two metal tabs beneath both the top screws:

The ribbon cable in the top-right corner connects the snooze buttons at the top of the device. Pull it out gently

The mainboard won't come out easily because the speaker connector on the back is still plugged in. It is positioned behind the left side of the VFD display.
To remove the mainboard, push the backside connection panel inwards - do this more to the right. If you feel that nothing is moving, there might be glue between the board and the case. Be extra gentle then. Keep pushing with as little force as possible. The glue should tear off eventually. If you are too violent or do this too quickly, the SMD components on the board which are covered by the glue might be torn away.


You will notice that the left side of the board cannot be lifted much. A little more room can be made by lifting the board on the right side and pushing it to the right a bit until its left edge can face towards the backside of the case as shown here:


Eventually here is the speaker connector. It's a really firm connection and the wires are pretty short so there is not much room to work:


I recommend the pliers to pull the plug out (away from the connector). If that does not fully succeed, you can also try to pull the entire board away - but well-controlled, please:


Congratulations, you are now here:

Disassembly: Remove Front Case Piece

Now you will see why we need a long-shaft TX10 screwdriver. Six of the eight screws we need to undo are deeply buried, and they are incredibly firmly stuck in there, too:
 

So be ready for some heavy torque. The first time it seems as if they are not designed to go out at all, and doing the same thing again later still requires some muscles.
These eight screws are considerably longer than the ones extracted so far so keep them apart from the others and don't confuse them later.

After the screws are out, the halves of the case are held together only by a sealing rubber strip inside. You will have to pull the front piece away from the back like so:




It is not shown in the photo but the back half needs to be pulled in the other direction. It is easiest if two people are involved. I would not recommend using tools like the spudger here because prying open will hurt the delicate plastic surfaces.
If you are done, this is what you see:


We don't need the back case so put it somewhere safe.

IMPORTANT: The tweeters protrude from the frame by 1 or 2 millimeters. If you put the front plate face down, they will touch the workbench surface which may give them a dent! This is what I mean:


So please consider putting something underneath to ensure that the tweeters don't touch anything. I am using three CD jewel cases here, one in the middle and two on the outer edges. Note that the tweeters (top left and right) now have the clearance needed:
 

Disassembly: Clean Speaker Fixing Screws

The bass woofers are held down each by another four TX10 screws which are initially covered in a white or yellowish glue blob. You will have to remove as much as possible of that adhesive because the screws are inoperable otherwise. The most important part is to remove the glue from the star-shaped socket in the screw head. I recommend a sewing needle that you poke inside the glue and then lever / lift it out:



The screw head should then look like this or better:


Even if there is surrounding glue left, turning the screw will loosen it whereas the glue remains around it. That's okay for now.
Do not attempt to push your TX10 bit through the adhesive (without removing any of it first). That will damage the screw head and push the adhesive even further into the head.

To disconnect the speaker from the wires, use the pliers again. The connectors each have a different width so they cannot be connected in the wrong polarity. If the connectors do not give way easily, wiggle them to the sides a bit while pulling. Note that there is a small white piece of board to connect the metal tabs to the copper wires that go to the speaker cone. This board will bend considerably - do not overstress it.


With the woofer out, you see that it sat on a rubber surround. What you also see is that beneath that surround, there is a plastic edge. It is a 45° bevel, however, the outermost edge of it is what may cause many speaker surrounds to fail if touched. You may consider sanding this edge to take off the 45° edge, or even widening the entire opening to reduce the risk of the new speaker surround touching any part of the housing.


The following detail shows where to smooth out the bevel's edge. The yellow mark is just a section to show the exact position of the edge in question.


And here is what superglue does to that rubber surround. The speaker was firmly stuck down here and needed to be torn off, doing considerable damage.


If you face something like this, you will also have to take extensive care of the edge around the opening because the remains of the superglue create another sharp-edged damage point for the new speaker.


Easy Repair / The Expensive Way

There is a German eBay seller who sends you a set of one woofer plus one tweeter for 23.89 EUR plus shipping. It's actually a Logitech UE Smart Radio speaker set but the chassis carry the same item numbers as the ones in the Boom so they are 100% compatible. This is the link to the offer: eBay
If Germany is too far out of reach for you, please check the national eBay market for similar offerings.
There are not many units left so this eBay item is likely to expire soon and then the last source for fresh speaker units in Europe is dry. So you may want to read the guide anyway because in the long run it's the only way to get back to a good bass.
If you prefer to replace the entire woofer, please consider selling the defective one via eBay or other channels. They are much too valuable to just scrap them, and others may give the actual repair a try. As these speakers have probably run out of production by now, we need to value every single one of them.

Advanced Repair / Cheaper but Demanding

I found an eBay seller in the Netherlands who has stock of speaker surrounds and who can also deliver the glue that is required. This is the link to the offer: eBay
Again, if you are outside the EU, there might be a more convenient source for you to get a repair kit. There are some manufacturers who have specialized in producing repair kits for all sorts of speakers. Eventually the measurements are what counts (image is not to scale!)


inside diameter: 50mm (blue)
outside diameter: 76mm (red)

outside edge width: 3mm (light green)
inside edge width: 3.8mm (purple)
embossment width: 7.0mm (black)

And this is what you get (actually you'll get two of the surrounds, only one of which is shown here):


The glue here appears familiar to me. It is water based and has the same smell as universal wood glue. After some days of usage, I found that it does not seem to dry out completely. The surfaces you applied it to stay sticky. So keep in mind to use it sparingly. There might be better choices but as it comes from the same guys that sell the replacement surround, I decided to use it.
To replace the broken surround, you will have to cut the old one away. The manufacturer used a highly powerful glue to keep things together which makes this repair quite demanding. You will have to use force but it has to be well-dosed not to break something accidentally.
We start by cutting the outer ring of the surround, so start cutting as far outside as possible so what remains on the metal frame is only the part that is stuck down by the glue:


When you are done outside, cut the other side of the surround. This is where the process requires a lot of attention. Prefer taking only just a little of the material away in multiple rounds. Do not cut too deep into the cone. Leave about 3.5mm of the original surround on the cone because that's the area where it covers the cone material which appears to be merely a sort of thick paper. It is easily cut, torn, or bent, all of which should not happen. So cut the soft material away first, which also helps you get a better overview.


 After this step, you should have this:


Seen from the top:


This is not a good base to mount the new surround yet. First the remainder on the cone should be removed to the minimum. Cut that down further to achieve a circular cut (or at least close to a circle). Do not cut beyond the radius that gives you considerably more resistance during cutting.


The result: another piece of the original surround is away now. What is left of it on the cone needs to stay.


I have tried to cut the remains of the original surround away from the cone with a scalpel to leave only the cone material itself. But the glue is so dense that I actually needed three blades. And it was not really much of a success. I cut into the cone accidentally, and as you need to apply exactly the right amount of force and maintain a precise angle at the same time, it is almost impossible to get that right. So for now I recommend leaving the inner ring of the surround and putting the new one on top of that.
Now for the piece of the original surround that is stuck down on the metal cage. It is far less delicate than the cone so we can get a little more violent here:


I used a firm blade and really quite an amount of force because this stuff does not come off easily. First you have a rubber layer, and below that, some really powerful superglue. You need to shave most of it off.
Make sure the blade never hits the cone! While this glue removal is really strenuous, you need to make very controlled movements. Cutting into the cone is likely to be fatal. Hitting the cone too hard may cause the coil to be deformed which is also fatal. Keep in mind that he entire cone assembly is not designed to go any other direction than the "roll axis" of the speaker. In other words: towards the magnet or away from it. Any other movement should be as gentle as possible.
If you don't care much about the black finish (which is hidden anyway once the speaker is mounted), you might consider using sandpaper or even an electric grinder to get rid of the rubber and glue. As the cone does not protrude there is little chance of damaging it thereby. But I did that and found the result is not very compelling - I'll show you what I mean in a minute.
I went the hard way and scratched away as much as I could by hand:


Which left me with this result:

 
Here's another closeup of the metal surface. I went too deep in some places where you can see the metal shine through. The surface should be smooth and even to allow for the new surround to be level and free of any warping.


Before you apply the glue, clean the surfaces with isopropylic alcohol or something of that sort. There should not be any dust or flakes of old glue. Do not use acetone or paint thinner because they might cause the remaining rubber material on the cone to become brittle which would decrease the surface available to stick down the new surround:


After that, apply a tiny amount of glue to the inner ring surface. Avoid the cone.


Next up, the metal frame:


I actually made a mistake here. The outer 3mm of the outside ring should be free of adhesive because the surround won't cover the surface completely. Therefore, around the new surround, some excess glue will stay sticky forever as you can see in the following image :(


Now for one of the most critical parts. The surround should have an optimal position, i.e. should be perfectly centered. It is easier if you start with the cone and try to put the new surround in a way that it covers the remains of the old surround to the same amount all around the cone. You may have to remove the surround again and start over. The glue is quite forgiving but take care that you do not stress the surround too much, otherwise its lifetime may suffer.
There is no photo of it unfortunately, but I found that putting a thin film of glue on the inner ring of the surround before mounting it creates a much better result, compared to gluing only the cone outer ring. But again, do be careful not to apply too much glue. When you push the surfaces together, any excess glue will squeeze out and ruin the result.
To avoid that, go around the innermost area of the glued area first to ensure that if glue is squeezing anywhere, it will not go to the front facing side and smear onto the cone, but rather get distributed outside / to the underside of the surround where it does far less harm. I used another cotton bud here that I pushed down where the overlap begins, then turned the entire chassis around. I did that multiple times, stepping further out with the cotton bud. Do not give it too much pressure at this time because the glue is still very liquid and may still be pushed inside where you don't want it.


During the hours and days after the repair, revisit the woofer from time to time and push the glued areas of the surround down gently if anything has lifted. It will settle eventually if the whole thing was centered right.

Notes on Reassembly

Putting the device back together is basically doing the above backwards but there are a few things to note:
  • check all connections. The metal tab connectors of the new speaker chassis should have the cables attached in the right polarity. Double-check this as you won't get back to this place easily later.
  • check speaker alignment. Do both woofers fit exactly? Did all screws go back in easily and to the same extent in all places? If not, reseating may be required.
  • plus the following:

Snooze Button Ribbon Cable

When you reassemble the case back into one, make sure you don't forget about that tiny little ribbon cable from the snooze button:


If you overlook the cable, it will stay hidden inside the case and leave the snooze button nonfunctional.
Make sure the cable sticks out at the maximum length, and pull it gently while pushing the case back together:


If you don't pull, the available piece of the cable may be too short eventually and pulling is no use then because the rubber seal between the case front and back side fixes it really strongly. So this must be done before or during the case is reassembled and fixed with the eight long TX10 screws.

Speaker Cable

As before, there is not much room to move the speaker connector back where it belongs. So place the board with its left edge facing the main board recess in the case so the connector and plug are close together. Then align them and push them together with the pliers. It is very hard to do this by hand. The connector may seem fast but actually it might still be loose. If you use pliers, it is much easier. Squeeze until the connection clicks into place:

Sanity Check

After mounting the mainboard might be a good time to verify the results of your repair progress so far. Even though the control panel is not yet attached, you can power up the Boom. If you are using Wi-Fi, the only connection you actually need is the power plug. Wait until the box has finished initializing, then use the infrared remote control or the SqueezeServer web interface to have the box play the test samples and some music. Also verify that the woofers as well as the tweeters work properly on both channels. If anything seems wrong, a typical reason is that the speaker connector is still loose and does not provide good contact.
If everything is alright, disconnect the Boom from power again.

Mainboard Fixing Screws / Metal Tabs

Make sure you place the metal tabs the way they were before. Note that the top-right metal tab pushes down on the snooze button ribbon cable so the cable must run beneath the metal tab, not across:

Previous FAIL

#1

Now here's a little gallery of my progress and former failures. Today I fixed the third chassis. The first one was really an accident in comparison:


There are many problems here, the most evident one being the excessive use of glue everywhere. As this was my first, I thought the glue might dry off and get un-sticky eventually. That's why I glued the outside surfaces, too, just assuming it would help to connect the surfaces better. But the glue never dried completely ever since, so if this woofer is pushed into its end position in the Boom case, it might be hard to remove it again without damaging the surround. It will stick to the case for sure, and just as well stick to the speaker, so it will probably tear. I might have to cover the outside ring with paper or something to prevent this from happening.
Secondly, the surround is poorly centered. You can see in the photo that it is shifted to the right by 1mm approximately. The resulting problem is that cone movement will not elevate the surround evenly. It is designed to be moved only in the axis that the cone is moving but will also experience pinching and squeezing where the degrees of freedom are reduced. Even if that happens ever so slightly, it will reduce the lifetime expectancy of this surround drastically. It might even be audible right from the start that something is not right.
And last but not least, I used my Dremel with this unit to grind the glue away from the metal frame, and quickly hit the metal. Once that had happened, I went around the entire frame to at least make it look the same all around. It may be functional but is just ugly.
I need to confess that I was too impatient back then, too. Even though there was no need to, I did it in a hassle and underestimated the impact on the result.

#2

The next attempt ended considerably better. There is still too much glue involved (you see it squeezed out to the cone) but the centering is better this time. The photo may suggest otherwise but that is just an optical illusion. Also I left most of the black finish intact on the frame.

#3

Eventually number three that I finished today. There is practically no excess glue inside and just a little outside. If the new surround were black, it would be hard to differentiate it from the original.


It's still not ten out of ten because there is glue left on the metal frame (still used too much) that might need to be covered but otherwise the repair went really fine. If you pay attention to the advice above, chances are good that your first repair will end up with something like this.

Good luck!

Final Words


Please let the speaker cure for some days (!) before powering it. The glue needs a lot of time to get firm enough to do its job.
High-end enthusiasts should consider doing the repair on both woofers at once even if only one has a problem. That's because the sound characteristics of the chassis will probably change a little bit, and it might be disturbing to find a different sound on the left than on the right. For most of us that's not a concern. Just mentioning...

Some legal stuff because you never know: please bear in mind that I am writing this as a hobbyist, not a professional. I describe personal ideas here which is only one of many ways such a repair can be achieved. I cannot guarantee that following this guide will lead to a good result, and cannot be held liable for any personal, physical, or monetary damage anybody suffers by following this guide.
I am open to advice if anything described here is wrong or can be done better. Please let me know in the comments if you find there is anything left to be desired.
Thank you!

19 comments:

  1. Hallo Joe,
    danke für die tollen Infos, die Bilder und die Links zu den Ersatzteilen. Ich habe dich noch einmal über das Squeezebox Forum kontaktiert (sehe nicht wie das hier gehen könnte).
    Viele Grüße aus Hamburg
    Andreas / andi_boom

    ReplyDelete
  2. Brilliant guide. Many thanks for your work, and, for publishing it in the amiable form as it is

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  3. Really good article. As a fan of Squeezebox (radios, ex-boom, touch) owner, I still feel that such a wonderful product should not been abandoned by Logitech.

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  4. Thanks a lot for the guidance. I've now ordered the repair kit and I hope to have more success with that than with my previous attempts at fixing the problem (fixing the cracks with silicone works somewhat but doesn't last very long).

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  5. Johannes - thanks for the detailed guide. Your instructions made for a very easy repair. My boom sounds great again, and since it is one of the very early versions signed by both Tim Westergren and Sean Adams I'm really glad I was able to restore it to its former glory. Cheers, Ken

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  6. Thanks, that is just what I was looking for. Much appreciated.

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  7. Excellent guide, thanks very much for putting it together.

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  8. Neat! It seems like pretty much 100% of those speakers fail over time, whether or not they were used. We never did find the root-cause because Logitech got rid of the Squeezebox group before they started failing. They put us over on that wonderful product -- google TV. I quit shortly after that :-/ Squeezebox was what I really cared about.

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  9. Did you think they may works?
    http://www.ebay.it/itm/2pcs-For-Logitech-3-inch-4Ohm-45W-Full-Range-Speaker-Stereo-Woofer-Loudspeaker-/122434028511?hash=item1c81a303df:g:SoUAAOSw~CFY5lRn

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    Replies
    1. hi there, looks like a perfect fit to me, not even expensive at ~36EUR for two. What is also great is that they are in new condition. The item number 170089-0000 is the same as in the Boom speakers. The only thing these replacements are missing is a rubber ring at the back side of the magnet to isolate against the Boom housing. I think that can be improvised though.
      Thanks for the advice anyway!

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    2. Glad to help your work and your great site
      May you suggest a method for the missing rubber ring?
      Regards

      Delete
  10. Just measured one of them. The material is a rather tight foam, not rubber so it is soft. It can be compressed easily to just a fraction of a millimeter in height.
    The outer diameter is 40mm and the inner is around 18mm. The thickness is around 2.5mm uncompressed. One of the images above shows both woofers from behind so both rings are visible. You can also see the counter side in the back of the housing where it becomes apparent that the hole in the woofer's back should not be covered. It is connected to the inside of the housing by its own little channel. So *do not* use a simple round adhesive pad, you will need a ring with a hole in it with a minimum diameter of 10mm (which is the diameter of the hole in the speaker backside cap).
    I did a little research, albeit with little success. Nobody sells exactly these, or I used off criteria.
    My approach would be the self-adhesive sticky foam pads which I am also using for Boom and Classic display repairs (see the respective posts in the navigation bar of this blog). Nobody claims these rubber spacers need to be round or air-tight. You could just arrange them in a square and it would probably work just as well.
    Anyway, this is not as critical as it seems. The important thing is to put just anything between the woofer and the housing to prevent vibrations between both parts to create rattling or other distortion by touching each other. And it should let the air channel in the woofer connect to the inside of the housing somehow.
    The outer diameter should be 40mm or more (any larger size will do just as well), and the inner hole should be 10mm or more. The thickness should not exceed 1mm if you buy rubber because it compresses far less than foam. If you find a ring made of foam, the thickness is practically insignificant. So almost any replacement will do.

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  11. Great guide, thank you! I just repaired my own Boom the weekend with a new ring. The old one was torn for about 1/3 of the diameter. The construction of the Boom is very good, no dust inside at all after 7 years of use. It was very easy to take apart and re-assemble. Because of all your warnings, I initially applied too little glue, but in the end I think I found the right dose. The sound is great again, and I can hear no difference between the left and right speaker. Thank you!

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  12. Great guide...thanks for posting!

    Am looking to order replacement woofers for my boom and found these.

    http://www.ebay.ca/itm/1pcs-For-logitech-3-inch-4Ohm-4-20W-full-range-speakers-Loudspeaker-car-Audio-/132099358553?var=&hash=item1ec1bc3f59:m:mI_jMBNG8XbjfwZYZmNvYUw

    noticed there are two versions - without terminal line or with. Which one do I need? Thanks in advance!

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    Replies
    1. Hi there, good find, looks like these are good replacements. You do not need the terminal wires, I think if they are included it just means that a cable is attached to the speaker which you would have to remove anyway. The Boom has internal wiring which you connect directly to each speaker's connectors so there is no need to buy more than just the speakers.
      Good luck with your repair! :o)

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    2. Thanks for the quick reply! Have gone ahead and ordered.

      I am also looking at replacing the VFD which is starting to show its age. I think you mentioned in that repair article that you might have access through Noritake local. Please let me know if yes and shipping to Canada.

      Thanks,
      Van

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    3. Dear Van, please send me an e-mail to jf [at] jf-it-services.de, I can offer you a MN16032G display (which is same as Logitech used in manufacturing) for 40 EUR plus shipping (which is around 7 EUR). It's crazy but Noritake in the US charge double that price for the same display as they are not interested in supplying small amounts to non-companies. It is totally different here in Germany where Noritake present themselves as maker-friendly and very forthcoming also regarding sales prices.

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  13. Great guide. Two Booms repaired and sounding like new. Four new speakers from China via ebay for £55.

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  14. Bitte schickt mir Eure Fragen ggf. an johannesfranke74@gmail.com. Posts hier bringen nicht viel, wenn sie anonym gestellt werden, weil ich sie dann nicht direkt beantworten kann.
    Sofern Eure Mails nicht im SPAM-Filter landen, werden sie zeitnah beantwortet. Danke! ;o)

    Please contact me at johannesfranke74@gmail.com if you have any questions. Using the comments here is not going anywhere if posted anonymously because I have no way of replying directly. Thank you! ;o)

    ReplyDelete

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