Squeezebox Touch - what I learned so far

Dear readers,

there have been a lot of contacts regarding the Squeezebox Touch recently. It's finally time to open a post on this subject.

So I would like to share here what I know. In contrast to most of the other Squeezebox models, I cannot share only just a tiny amount of "how to repair" approaches here as in my opinion the Squeezebox Touch is not repairable in most cases. You will see why shortly.

Disclaimer

Spoiler: the tone of this post is going to be very dark and pessimistic. This is due to the fact that the Touch really frustrated me. I had at least 15 units on my bench, and only one was recoverable because it was just the IR receiver that failed whereas everything else was okay.

Hardware-wise the Touch (and Radio) create a sharp contrast to the older models where repairability was a lot better. I hope nobody feels attacked by the straight-from-the-heart utterings.

As usual, I cannot present any schematics here to explain things as Logitech won't ever disclose them. So it's a mix of guessing and uneducated reverse engineering. Everyone who can shed more light on the Touch internals is invited to share more information in the comments or e-mail me at johannesfranke74@gmail.com so I can complete the information given here with some better-founded knowledge.

Failure Modes

A rather popular issue with the SB Touch is that it stops receiving infrared commands whereas all commands from the mobile app or Logitech Media Server are processed immediately. While it is unclear why it happens after all, the replacement of the infrared receiver diode is possible and explained further below.

Other than that, there are only two capital failure modes that I can report here: one is the display flex cable being damaged as a result of too little care when disassembling the Touch. If you read the disassembly guide below, the chances this happens to you are far lower. This can certainly be recovered by using a new display. There is plenty of these displays or front panel assemblies available nowadays due to the other failure which is unrecoverable, and usually the front panel is what survives.

Last but not least, the most critical failure presents itself in the form of one or multiple power regulator components burnt out on the mainboard. Unfortunately, they are spread to both sides of the board so the device needs to be completely disassembled for a complete inspection.

As far as I have learned, the issue is caused by:

• reverse polarity - when the wrong power supply was connected
• too high voltage - ditto
• a combination of the two
• self-destruction - yes, I'm not joking. This may also happen
• MAYBE: dying power supply causing high ripple current
  

Details on Power Supply Issues

The Squeezebox Touch comes with a wall-wart power supply that delivers regulated 5V at a maximum of 3A which the Squeezebox never actually needs, but this is the specifications anyway. The power is delivered to the device by the regular 5.5/2.1mm barrel jack connector with the positive terminal inside and the negative on the outside metal sleeve. So there is nothing in the way of connecting a 12V Boom power supply or even a 18V Radio power supply which have the exact same style of connector. If you are lucky, you picked a 5V Classic power supply, that would not do much harm but might deliver too little power. The barrel jack is the connector style used for the vast majority of consumer devices so it may seem tempting to try just any power supply whose connector fits when the original power supply fails. Sadly, this has probably bricked a lot of Touch devices that have appeared to be faulty to their owners, and only the wrong choice of power supply actually killed them.

The Squeezebox Classic (a.k.a. v3) is well known for issues which actually stem from the aged power supply whereas the device is working perfectly with a fresh one. Likewise, the Transporter has a built-in 5V power supply suffering from the same root cause: the output filtering capacitors dry out over the years and consequentially the power supply is no longer able to deliver the current and voltage needed for operation. As a result, it starts up which may cause a spike in the output that quickly collapses because the capacitors are not flattening the ripple any longer, the feedback circuit detects the failure and restarts again, repeating this process indefinitely. The consuming device may either get no power at all because it breaks down before anything even has a chance to start up, or even worse, the consuming device is also turning on and off constantly at a rather high frequency which might be destructive and cause voltage spikes in the consuming circuitry. So dying power supplies might tear things down with them as they fail. My recommendation therefore is to check them regularly if they are 5 years or older, and see whether they can still deliver the current and hold the voltage under the load they are designed for. This requires a battery tester though which almost no household will have available.

It is a true dilemma. Waiting for the power supply to fail may cause loss in more hardware if that gets damaged by erratic input power. However, replacing power supplies for good measure without knowing if it is getting unstable is wasteful and the opposite of sustainability. Unless you acquire a battery tester that will give you a qualified answer on the status, you are technically flying blind and need to decide what is your preferred approach between these two.

All this is probably true also for the Touch power supply. It is rightfully the prime suspect when trouble comes up in just any Squeezebox, and is also the cheapest fix (if it helps) as there are tons of offerings for these ubiquitous sorts of power supply. It's a great relief for all the Squeezebox owners if they learn that their Squeezebox is in perfect shape despite the symptoms observed, and a new 10-dollar power supply was the solution. Even if it does not resolve the issue, it's rarely a waste of money as the Logitech stock power supplies reach the end of their life after 10 to 15 years at best when constantly powered.

So a lot of people are replacing the stock power supply with a different one, unfortunately in many cases without carefully checking out the specifications first.

What to Buy

So to repeat the above another time: double-check specifications before you connect any foreign power supply to your Touch, or else!

Watch for these data:

• output voltage: 5V stabilized DC (no other voltage is acceptable!)
  
• output current: 3A (if it is capable of delivering more, it's no issue)
• connector: 5.5/2.1mm barrel jack
• polarity: [ + ] inside / center pin  and [ - ] outside sleeve / ring

It does not matter if it's a wall-wart / plug style or a brick like it's typically used for notebooks. I would prefer the latter as they have more room to spread heat and have good chances of lasting longer.

There are audophile circles that proclaim snake-oil power supplies ranging from 200 to well above 700 US-$, each!. I find it hard to believe that a mostly digital device will profit from such a power supply but one bonus will be that it will last longer than the dreaded wall warts. In my humble opinion, it's only truly audiophile if, on top of that, you use the digital output, bypass the built-in Touch DAC, and use an external DAC weighing in at 2000 US-$ minimum to recondition and de-jitter the signal input.

Basically the Touch DAC has a pretty impressive quality so it will be good enough for most people, even when a crap power supply is used.

Why the Choice Matters

Input protection in the Touch is practically non-existent. While a Boom will easily tolerate more than 12V of input (still not recommended to try though), the Touch bricks itself immediately if any mistake is made. There is no input fuse, no reverse polarity protection, really just nothing. There are lots of power regulators in the Touch but they fail to step down a too-high input voltage, will fail themselves, and that will damage just about everything between the input jack and the CPU (central processor). Eventually it looks like a short circuit in just every corner.

As the Squeezebox / UE Radio is the same hardware development generation as the Touch, the same goes for it, too. Do not try just any power supply but only one with the same specifications as the original. Just to be complete here.

Findings

Documenting here some of the cases I have seen already.

Infrared Receiver Defect

Nobody knows why, but actually the black 3-legged infrared receiver diode fails in some units. You may notice at first that the Touch gets less responsive, or only picks up IR commands if you point the remote control directly at it from a short distance. There are reports of this issue building up slowly, others had a completely failed receiver diode from one day to the other.

The original receiver diode looks pretty solid and is probably not the lowest quality. Maybe it's designed for 3.3V and driven with 5V which may slowly destroy it.

As is often the case nowadays, it's hard to find an exact match when it comes to a replacement part. But infrared diodes are mostly compatible with each other as long as you choose the correct response frequency which is 38kHz for the Squeezebox product range. Deviations in the pinout between the original and replacement are not a big problem. The parts are pretty large and there is some room to swap pins if needed.

See further below for instructions to replace the IR receiver if yours is giving you any trouble.

Blown Power Regulators

Well, if you see any blown-up or warped component such as these, it's practically time to give up. Sad as it is, the damage goes a lot further than the eye can see.

<<photo>>

Disassembly

This is what you need to open your Squeezebox Touch. Be sure to read everything here, it will keep you from making expensive mistakes that many have made already!

Tools Needed

1. a TX-10 torx driver for the two screws that attach the metal stand
2. a driver to open the case
   
3. a PH-1 screwdriver if you plan to get the mainboard out
   
4. to lift the front panel:
1. a spudger or other flat piece of metal OR
   
2. a suction cup

Advice

There are multiple different types and lengths of screws used. It's recommended to keep track of which screw went where and not get them confused later.

Also, take a lot of photos along the way. For instance, there are ways the microphone wires are laid out to keep them from getting squished.

Procedure

Many SB Touch are damaged by curious people who want to have a look inside, be it to fix another issue or just to see what makes it tick. There is a high risk of damaging the display connection if the disassembly is not done very carefully.

Here is how to do it:

Step 1: Remove the Stand

Step 2: Remove Casing Screws

Step 3: Separate Front Panel from Back Case

This is the most critical part actually. Be slow and careful here!

Step 4: Open the Flat-Flex Connectors

Step 5: (if needed) Get the Mainboard Out

Assembly

Step 1: Microphones and Wiring Placement

Step 2: Reseating the Mainboard

Step 3: Plug Microphones

Step 4: Connect Flat-Flexes for Display

Step 5: Attach Front Panel

Step 6: Close Casing

Step 7: Re-Attach Stand

Measurements in a Working Touch

I had a lot of questions on the reference voltages that can be found in a working Touch. This is supposed to help people find out what parts are broken.

 

Infrared Receiver Replacement

The Infrared Remote