Tired of seeing this?
No question, the Squeezebox Boom is a fabulous device. However, some small mistakes in the design as well as in the documentation make it susceptible to some annoying symptoms of aging, becoming apparent by a shadowy / fading display, or the display showing nothing at all any longer.
What happened?To make it short: we have a mix of aging of the display itself, plus aging of the power supply circuitry. Both lead to faded or completely dark displays.
Edit 2020-06-08: more details on this can be found in this new blog post: https://joes-tech-blog.blogspot.com/2020/06/vacuum-fluorescent-displays-how-they.html
The Squeezebox Boom, like many other devices of the Squeezebox series such as Transporter and Classic, employs a Vacuum-Fluorescent Display (VFD) for user interaction and entertainment. Look here for more info: Wikipedia.com
Why VFDs?VFDs are kind of old-school today. Most people know them from (older) table calculators, cash registers, video recorders, dash displays in cars, etc. Their main advantages are that they are pretty bright and fast. There is hardly any "lag" when a pixel is switched on or off. They are much better in this respect than LCD displays. They emit a bright cyan/green light which can be easily modified with filters to grey, green, orange or whatever.
I think Logitech chose VFDs because they simply look good in operation. As the Squeezebox UI uses a lot of animations and visualizations, VFDs are the displays of choice for this kind of application.
Logitech picked the Noritake MN16032 glass module and implemented the driver themselves. So what you need is a MN16032, not one of the GU160x32 modules that Noritake is selling as well. The GU series is basically the glass module mounted on a PCB with some microcontroller and power supply. The Boom contains all of this.
Edit from 2017-06-19: Noritake Itron is updating the MN16032 to a new revision. The previous one is the MN16032G, the new one is named MN16032GB. You can purchase any, both will do.
One main disadvantage of VFDs is that they are aging, just like old cathode-ray tubes (CRTs known from TVs), or plasma displays. The phosphor coating of a pixel burns up over time while it is on. The speed of decay is determined by the time the pixes is on, and its brightness. The longer and brighter a pixel shines, the faster it will fade. So aging is no issue when the display is completely blank.
The outcome of permanent content creates ugly artifacts such as these, from a display that actually shows "all pixels on":
Some static text has been in the same place for a very long time. It has burnt in so much you can read the shadow of something like "RDSI: 19,392Mbps" in the third line. The text in the bottom line seems to have varied but not really much as there are clear shadows of M, H, D and T characters.
How does Logitech make it worse? Screensaver!This process cannot be stopped except by not using the display at all. But things can be improved by limiting the maximum brightness of the display, and not using what Logitech prefers to call "screensavers". Because these actually do the exact opposite. A permanent display of the clock time or the current weather will lead to partial fading of your display. That's not what I would dare call a screensaver.
Moreover, the clock time is displayed in the same place all the time. It does not "wander around" on the display to make use of many different pixels and use them up equally. As a result, most Boom displays fade in the center first. The photos above show how bad this can get. It is clear to see that the shadows four large digits exist where the clock time usually appears.
Generally I accuse them of not mentioning the risk of VFD aging anywhere in their documentation. It's a shame but the people responsible for the documentation probably weren't aware of the problem at all.
Automatic Brightness and Why I Don't Like itBesides destructive screensavers, Logitech screwed up the automatic brightness behavior. While it is possible to set a minimum brightness and a sensitivity, it is not possible to specify a maximum brightness. And in my opinion, the sensitivity is a bit too far on the high side even on its lowest setting, i.e. the display is at the highest brightness most of the time.
Imagine you have a Squeezebox Boom on your bedside to act as an alarm clock. Sure you want to see the clock time at night, but what about daytime when you are at work? Daylight will cause the automatic brightness control to drive the display at its maximum capability, without anyone even looking at it. I think that is how most displays suffered from premature aging, while nobody cared.
So my recommendations to increase the life expectancy of your displays are:
- don't use automatic brightness. Set a fixed brightness as low as possible
- never exceed brightness level 3 (out of 5)
- in standby, do not have the display show a clock time or anything else that resides in a static position on the display
VFD Filament Power Supply Design IssueUnfortunately, there is also a design flaw in the Boom concerning the filament power supply. The filament wires are directly behind the front glass. In dark environments, you can see them in the form of six horizontal glowing lines. The Boom VFD has a filament voltage of just 5 Volts on the left and approx. 2 Volts on the right side of the display, but a current of up to 2 Ampères! The supply circuitry consists of SMD components so small they are hard to see, and they run almost red hot. I have measured 100°C and more. Here is a picture taken just after powering on a mainboard, showing the top-right edge of the board. Behind the display there is at least one transistor, MOSFET or something that heats up pretty bad:
It is likely that one of these components causes the lower of the filament voltages to become unstable which causes the display to look ugly, to fade, or to go dark completely. I have found the following symptoms so far:
- right display voltage ramps up to as much as 5.5 Volts after the PSU is connected. The display initially looks good, then begins to fade. The comparatively high voltage on the right means there is no more voltage drop across the filament which causes the electron emission to stop
- right display voltage is 0 so the circuit is open. No electron emission can take place then
The left side of the display is constantly supplied 5V. I think the left side is more or less directly connected to the main power supply whereas the right side is sub-regulated, and that regulation circuitry fails.
The hobbyist in us immediately assumes that there are electrolytic capacitors involved which evaporate their electrolyte over time, especially in warm environments. Known issue with tons of old electronic devices, but not in this case. As far as I can see, the circuitry around the display voltage generation does not use electrolytic caps.
Logitech does not make technical documentation for any Squeezebox device open for now, so it is hard, if at all possible, to find out what is the failing component.
There is one more thing to say about Logitech's mistakes: many Boom owners will have noticed that their Boom is pretty warm all the time, even if the unit is in standby and configured not to show anything on the display. This is due to the fact that the Boom keeps the VFD filament powered all the time! Even if nothing is shown on the display and the unit is in sleep mode, the filament power circuitry, besides some more components inside the boom, is constantly powered. Eventually you can switch on the Boom anytime through the Squeezebox Server UI, an app, the IR remote etc. so it needs to be aware and keep parts of its control logic running, e.g. the IP interface, the Wi-Fi board. But is is clear that Logitech did not focus on power saving whatsoever. I assume that the difference between standby and "on" is absolutely minimal. Maybe the power amplifier that supplies the speakers is really off during standby. Everything else is fully powered. That's why the Boom is instantly ready when we tell it to do anything while it is standing by.
This is a thermal picture of my Boom after 6 hours of standby with nothing on the display at all:
The constant "need" to supply the filament voltage surely adds to the aging of the circuitry.
By the way, the filament itself does not contribute to the display aging. While it's a shame the filament is always powered, the display just suffers if pixels are on. So the main concern here is waste of energy.
What you need for this repair is:
- a T10 torx screwdriver
- a spudger or flat but stable piece of plastic to get off the grilles and remove adhesive pads
- straight pliers
- Noritake MN16032-type VFD glass module (MN16032G is current)
- desoldering station (~ 300 °C, no more than 60W)
- soldering iron with fine tip (~ 285°C, no more than 40W)
- isopropylic alcohol (95% pure or better) to clean things up
- recommended: 3M 08984 adhesive remover
Tools Not Recommended
The solder pads on the main board should get as little stress as possible. So they should not be heated too much or they will easily come off the board, adding a completely new level of difficulty. So please use temperature-regulated soldering equipment, the reliable / expensive sort if possible.
I do not recommend using solder wick to desolder the old display. It takes too long and will not completely remove the solder in order to loosen the display.
When it comes to cleaning, avoid paint thinner or any other stuff that harms plastic surfaces. It is probably no good for the mainboard, too.
Steps to get down to the mainboard:
- remove the speaker grilles (left and right)
- unscrew the control panel, four T10 torx screws (one in each corner)
- pull the control panel flat flex cable
- unscrew the mainboard, five T10 torx screws (one in each corner and one in the center)
- pull the mainboard out
Disassembly: Remove the Speaker GrillesThe 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 thin shiny 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 PanelNext 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 PanelOnce 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.
Also make sure not to pull the flat flex any other direction than directly away from its connector. If you pull upwards away from the board with too much force, you may lift the connector or tear the cable.
Disassembly: Remove MainboardWith 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 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, thereby lifting the mainboard. It is recommended to push the right edge out first because of the speaker cable that prevents you from pushing the left edge out as easily. If you feel that nothing is moving, there might be glue between the backside of the board and the case. That is because Logitech production did not have the time to wait for the glue to cure before mounting the main board. 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.
A little more room can be made by lifting the board on the right side, then 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, with the right board edge pointing 90° away from the enclosure. 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:
Preparing the Mainboard
Now that the board is out, we need to take a few steps before the VFD can be desoldered.
First the Wi-Fi antenna that is stuck to the board at the top edge needs to go. It's the metal tab at the bottom edge in the following picture:
Why it needs to go? Because the sticker covers three of the display pins we are going to desolder:
So lift the black tape gently. Make sure you do not bend the antenna:
The antenna is usually glued to the black strip with another black adhesive foam pad which won't come off in one part. So at the bottom of it, you will find remains of the pad which I recommend to remove completely to make way for a new pad:
We will have to scrape down layer by layer. Beneath the foam, a tough layer of adhesive comes up:
This is where 3M 08984 makes things really easy. Just cover the entire pad multiple times and let it dissolve the adhesive. You can also use isopropylic alcohol but it will take more time.
One more layer of adhesive comes off now:
Eventually some spudger work removes the last bits of the adhesive, leaving only the metal. A Dremel will also do nicely. The surface will get scratched on the way but that does not do any harm. The antenna is still going to work as it should. Just ensure that the surface is clean so the new foam pad can hold it properly.
The black plastic strip probably left a paper-like layer on the board. Use adhesive remover or alcohol again to remove what is left:
Besides the three display pins we just uncovered, there are 15 more pins on the other side. All of these need to be desoldered:
You might find that Logitech has put some glue right on top of the display pins to tuck down the antenna cable. That's unfortunate because that glue is really tough. If you find something like this:
...be prepared for some extra hours. The upper picture shows a rather mild extent of the problem where only a fraction of the glue blob covers the soldering spots. The lower is rather extreme with at least five pins being completely covered and in need to be excavated.
In this state, it is rather easy to remove the antenna wire. Just perform a careful cut beneath the black wire into the glue material to create a slot through which you can push the antenna cable out sideways. It should not be in the way during soldering anyway.
The problem is that you cannot rip the glue off the board because there is a high risk you will tear off the SMD components to which the blob is firmly stuck. It won't come out as one piece and is potentially stronger than the adhesive that links the soldering pads to the main board material. You will need a sharp blade of some sort, and make sure that you do not touch the mainboard while cutting through the glue blob because you might easily damage traces or SMD components. Violence is definitely not an option here. "Shave" off the blob carefully, layer by layer, until the pins you want to desolder are free.
So far I found that the glue resists high temperatures so you cannot melt it. It will turn black but not go away. It will get a little bit softer though. Dissolving it with some chemical might work but my attempts with 3M adhesive remover and isopropyl alcohol were miserable failures as they changed nothing. So it comes down to a spudger or a blade and tons of patience. You must never slip because cutting any vias on the PCB might come out fatal. I have honestly spent hours with that, which is still better than doing this in a rush and creating yet another brick.
Once the display is out, the surface of this area is flat and thereby easier to work on to remove remaining glue.
Removing the Old DisplayThe display glass module is stuck down to the mainboard with three adhesive foam pads. You can see two of them at the lower edge of the display. Right edge:
And left edge here:
The third pad is hidden beneath the top edge of the display and is very hard to reach.
You can find the foam pad positions in the pictures coming up.
What is also important to note is the black strip on the upper edge of the display. The purpose of this is to protect the ambient light sensor (you can see it a little to the right or the center in the next picture) from picking up the display light which would distort ambient light measurements and confuse the automatic brightness circuitry, if you ever use that at all (again, I don't recommend it but it's still everyone's own decision).
Remove this strip and keep it for the new display.
Before desoldering the display, let's detach it from the sticky foam pads. I recommend a sharp blade or spudger. Be sure to stay as close as you can to the glass. Do not try to cut the foam pad anywhere closer to the mainboard because you will probably damage or even rip off SMD components hidden beneath the display.
The critical places are shown in the following picture. The display was already removed before, and the top side of the board is actually facing down on the photo. You can see the foam pads (left/top, center/bottom, and the black one right/top) as well as places where SMD components are in your spudger's way potentially:
So again, stay on the glass side when you cut the pads! It's really vital.
Also take care to stay in line of the foam pad. The next picture illustrates how you might accidentally hit an SMD component on the way if you don't stay under the display. As cutting through the foam pads requires some force, you might easily slip or break things. Be gentle and controlled, and take your time for this.
The third foam pad needs to be cut "blindly". Just push the spudger in so it touches the glass and is as far as possible from the PCB. Now that the black tape that protects the light sensor is gone, you can get a good view from the top edge while you cut the pad.
Eventually, the display should come loose like so:
Desoldering time. I recommend using a vacuum desoldering station set to ~300°C with a 0.8mm tip. There is one SMD capacitor that is quite close to the first three pins as shown here:
Try to work around that capacitor. Its plastic base may melt a bit, that's no problem. But try not to bend the capacitor as that would cause a considerable stress to the SMD pads it is soldered to. It can't be good if you happen to snap it off along with its solder pads.
It is hard to show here but I found desoldering easier when the display faces upwards, mostly because you can easily see when a pin is moving free, indicating that all solder around it is liquid and you are ready to remove it. So for each pin, I do this:
- hold the board with the display facing down
- put the desoldering nozzle on the pin to be desoldered
- flip the board around, keeping the nozzle on the pin (nozzle now points upwards)
- keep the nozzle in place until the solder liquefies
- wiggle the nozzle around the pin. The display pin should move accordingly on the top side of the board. As long as it doesn't, stay where you are (should only take a few seconds, otherwise something else might be wrong)
- activate vacuum and keep wiggling while the solder is being sucked away. This ensures that the pin is free afterwards and does not solder itself back anywhere
- if a pin cannot be desoldered, add some fresh solder with a soldering iron, if need be, on both sides of the board. Make sure the solder was liquid on both sides of the board, then retry desoldering
An alternative approach is to clip all display pins first (you are probably discarding the old display anyway), then get rid of the glass module and desolder each pin separately. Might be easier because you can then use pliers to pull the pin whilst desoldering it.
Once the display is out, check against a light source. All 18 holes should be free now. If any is clogged, use the soldering iron again to fill it with fresh solder, then remove it all with the vacuum station.
Mounting the New Display
So this is where we are now:
Depending on the state of the foam pads, we can reuse them by putting double-sided sticky tape on top of each like so:
If the foam pads are in a bad shape, feel free to remove them. It is a time-consuming piece of work though. Keep in mind that there are SMD components covered by some parts of the foam pads so you cannot use a metal spudger here. Instead, you will have to use adhesive remover, something soft (plastic spudger, Q-tip, whatever) and a lot of patience again.
The foam pads should be replaced due to the delicate nature of the glass display. It should be stuck down somehow or the display will experience vibration and its pins might wear out sooner or later. So if you removed the pads, try to obtain new ones as close as possible to the specification of the ones you just removed. The thickness is about 2mm, and each is about 30mm x 6.5mm in size.
Apply the black tape to the new display. If needed, use double-sided tape if the adhesive stayed with the old display:
Carefully position the new display on the PCB. Align the pins so they are in a row and have equal spacing between all pins. Insert the pins into the soldering holes, then, while keeping a safe distance from the sticky foam pads, use the white frame that is printed on the PCB to align the display. When you are sure that the position is good, push the display down onto the sticky pads.
Side view before resoldering:
Do the 18 pins, using solder sparingly to avoid shorts. Eventually the pin spacing is only 2mm so using a fine soldering tip is definitely recommended. Do not heat up the pads for too long to protect them from coming off the board.
Final CleanupAfter the soldering work is done, I recommend to remove the flux that is left from the factory assembly of the old display (well, Logitech did not really excel there), and probably also from the solder you just used. Flux is corrosive and some are even hygroscopic which might cause trouble later. Isopropylic alcohol is perfect for removing the flux and won't cause any trouble electrically, plus it evaporates quickly. Use a brush or a toothbrush and generous amounts of alcohol, wipe across the solder pins until the liquid that comes off the board is no longer brown or yellowish but clear.
After cleanup, the site should be nice and tidy:
To reattach the Wi-Fi antenna, I recommend a double-sided sticky foam pad cut to size:
Before you stick down the antenna, ensure that its body will not touch any of the surrounding metal contacts. It should be centered between the contacts next to it in all directions. The following photo shows it between the first group of three pins of the VFD on the left, and the three contacts of the IR receiver diode on the right:
Eventually, the inside of the control panel's screen should be cleaned up so there is no distortion from it. Over the years, the screen collects some fine dust that covers the entire inner surface and might lead to a milky / blurry vision. This is a good opportunity to remove all dirt from it. You may need multiple passes with a soft cloth and alcohol. No worries, there is no coating on the screen. But please ensure that the material you use does not cause any scratches and won't attack plastic surfaces by any means. Paint thinner for instance is sure to ruin the job.
The picture illustrates how smears from a previous cleanup attempt remained and can be seen against light:
These smears will be illuminated by the display and we just don't want that. Just keep on cleaning until all that crud is gone. It will improve the experience even more.
Notes on Reassembly
Verify EverythingAs we get closer to the first power-up after the repair, it's time for a full check of our work:
- Check all solder connections for shorts and cold joints. A continuity tester is great for this. The groups of three pins on the left and right side of the display have the same potential so it is okay if they appear shorted. But no neighbors among the remaining 12 pins should be shorted
- If you find that the solder on a pin looks dull, or the pin can still move, heat the connections in question up another time
- If you want 120% safety, measure each display pin against the respective trace on the mainboard to see if any connection is not actually working
- Ensure that the reattached Wi-Fi antenna does not have direct contact to anything
Speaker CableAs 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, later causing dropouts and distorted sound. If you use pliers, it is much easier. Squeeze until the connection clicks into place:
The speaker cable can be pulled out of the casing by some millimeters which gives you more freedom. But consider that there is not much room to stuff the wires away eventually so keep the wires as short as possible.
Sanity CheckAfter 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. Just observe whether the display lights up bright and shiny after a maximum period of 5 seconds. If it does, see if the board passes the boot sequence. You may use the IR transceiver, the mobile app or the Squeezebox Server interface to play some music for verifying that the speaker connection is intact. If everything works, congratulations! You are practically done. Just unplug everything for the final assembly.
If the display stays dark, you hear noises, smoke comes out somewhere, detach the power supply as fast as possible. Let's just hope this never happens. There is no technical support for that situation.
Mainboard Fixing Screws / Metal TabsMake 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:
Please make double sure that the unit is not powered while you put the screws and metal tabs back in. They are electrically conductive and any shorts on the mainboard are probably fatal.
More InformationYou might have noticed that some photos and part of the disassembly / reassembly instructions is familiar. I have copied it from my other blog entry about how to repair the bass woofers of the Boom. See here if you are interested: Bass Repair
Final WordsSome 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.