Logitech / SlimDevices Squeezebox Classic Display Replacement Guide

Squeezebox Classic (v3) Display Replacement Guide

Hi folks! With the Squeezebox Classic 3, a rather rare item was here today for a display refreshment. I'd like to share the experience with you of course.

Please take a look here for general information on VFDs and what is their problem.

If your Squeezebox Classic display has faded or has shadows, you've come to the right place.

An example of what I mean:

Or even worse:

You'll see the new display in comparison later.

 

Tools Needed

What you need for this repair is:

• a T10 torx screwdriver
• a spudger or flat but stable piece of plastic to remove adhesive pads
• Noritake MN32032-type VFD glass module (MN32032A is current)
• desoldering station (~ 320 °C, no more than 60W) and leaded solder
  
• 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.

 

Disassembly: Open the Case

Remove the two screws indicated here:

 

You can remove the front piece of the housing now, if it didn't fall off already. Beside these screws nothing holds them to the back casing but you may need to pry the gap between both halves a little.

What you are going to see: the display in its full glory, the IR receiver diode, and a row of connection pins.

Please take a second to check the inside of the front cover. It is typical that it collects a very fine dust on the inside due to static charge. If you move your finger, or a cloth, over the surface, and it is then grey or even black, some dust has accumulated. It causes the display to appear milky so it should be removed for the desired like-new experience.

What you may also see is that people before you have tried to remove the dust. I would say that was not a perfect improvement though. The dust is gone but the surface is full of thin scratch marks:

Again, this photo is from is the inside of the display cover. It may look similar on the outside though.

Be aware that we are dealing with plastic here, no glass, and the surfaces are absolutely delicate so if you go off and clean it, use the softest materials available. We will come back to this later.

 

Disassembly: Loosen the Mainboard

Undo these four TX10 screws indicated: After that, a slight push on the connectors at the back of the device is all you need to get the board out of the case completely.

A quick view of the back side of the mainboard: 

Now, similar to what you can find in the Boom repair blog, you will have to follow these steps:

• desolder the display (18 pins, 2mm spacing)
• cut the adhesive pads beneath the display

 

Desoldering the Display

To desolder the display pins, my recommendation is you use a quality vacuum desoldering station. Alternatively, you may try one of the manual one-shot vacuum pumps but it's considerably more work. As the old display isn't worth anything, you can also cut all its connections with a side cutter, then get rid of the display, and eventually desolder each pin one by one. You will still need to free up all the 18 holes one way or the other to put the new display in.

While in the Boom repair guide I tried to explain how to desolder with a vacuum station in pure text, I have created a video here that shows the desoldering process on the Classic: https://www.youtube.com/watch?v=XDod-obw6Iw

Once the display pins are free, we can go ahead and remove it entirely.

First off, the display is stuck to the mainboard with two adhesive pads, one on each side. Luckily there is just the flat PCB surface directly under the display so there is little risk of damaging components. Still, there is no need to be careless. Some traces hide under the display and they should not be scratched.

Use a spudger with a sharp edge to cut through the adhesive pads on both sides.

 

Viewed from the side; observe how the spudger is slightly bent and the cutting edge stays close to the glass, not the board (to avoid accidental damage to PCB traces):

See here the remains of the adhesive pads once the display is out:

I can totally recommend the following to remove the pads. Isopropylic alcohol will do it but more slowly. The 3M chemical is a powerful agent that softens up almost any sort of adhesive:

You'll probably have a lot of trouble removing the pads without a solvent. While it is not vital to clean it up perfectly, why not take the time?

Using the 3M stuff is easy. Just soak up the remains of the adhesive pads and give it some minutes to do its magic. Soak it up another time and let it sit for a minute. After that, the pads can virtually be pushed off from their position even though I would advise you to pull them off to avoid smearing the adhesive remains.

And there will be some remains once each pad is gone. The adhesive layer is still there but now you can wipe it up with a cloth. If need be in multiple steps, and with another application of 3M. Eventually clean everything up with Isopropyl Alcohol.

The result rewards you with a board good as new:

 

Putting the New Display

The adhesive pads mainly serve the purpose of keeping a little distance between the display and the board (about 2mm, I would guess), and ensuring that the display cannot move. You could set the new display flat on the mainboard with no distance at all, and use double-sided adhesive tape to secure it, however, that spacing might make sense, so this is a nicer alternative:

This is basically double-sided tape with a foam layer in between. It is available in all shapes and sizes and thicknesses. Try to find one that has about the same thickness as the original pads. Craft shops are usually full of them, otherwise eBay or Amazon might be your source of choice.

Before you put the adhesive pads down, please exercise placing the new display. Its 18 pins need to go straight into the holes, none of them should be stuck anywhere. If that works out, stick it down with as many adhesive pads as you desire.

Now we can start soldering the pins. After you soldered the first three pins on one side of the display, take a look at it from the side to ensure that the distance between board and display will be the same on both sides. Therefore, it is best to solder down the other three pins on the far end before turning to the twelve pins in between.

Logitech's production process is mostly automated but the display was hand-mounted. You can see that from solder flux residue around the pins of the old display. As it is likely that your solder wire has flux built-in, more flux will accumulate. Besides looking ugly, it may also be pretty aggressive to the board so my recommendation here is to remove it all after you are done soldering. Isopropyl is ideal here again, best combined with a toothbrush.

With little effort, you can make it look like this:

Please inspect your work carefully. The outer sets of three pins may be shorted. That's not a problem because they have the same potential anyway. Check the other pins, too.

If you have a multimeter or other means of continuity checking device, use that to ensure that each pin is a different potential than its neighboring pin(s).

 

Here is what these pins are, it may help you determine pins that may or may not be connected to each other, and the expected operating voltages:

Pin/group	Specification	Typical voltage range	Description
1..3	F1	+5V DC	Filament Voltage 1 (block of three pins on the extreme left)
4..5	NC		Pins left out (not present) to separate filament voltages from other signals
6	VDD2	+55V (!)	High-voltage rail for grid. Be sure not to touch this pin or accidentally short it to any other pin
7..8	VSS (GND)	0V	Digital ground (these two pins are internally joined together)
9	VDD1	+3.3V	Digital supply voltage for internal circuitry
10	BLK	unknown	Display blanking input
11	LAT	unknown	Data latch control
12	GCP	unknown	Tone control pulse
13	SOUT2	unknown	Serial data output 2
14	SOUT1	unknown	Serial data output 1
15	CLK	unknown	Shift register clock
16	SIN1	unknown	Serial data input 1
17	SIN2	unknown	Serial data input 2
18..79	NC		Pins left out (not present)
80..82	F2	1.4V to 3.9V	Filament Voltage 2 (must be lower than F1, in the block of three pins on the extreme right)

Once that is done...

Testing time!

For the first test, I left the board outside of the case so I could quickly intercept if anything goes bad. Greeted with a logo so bright it is almost blinding:

Nice! Putting it all back together is basically doing the disassembly in reverse. 

But while it's still open, you may consider to review the SMD capacitors. If the SB3 appears to become unstable, for instance reboots when playback starts, or reboots multiple times before it can be used on powerup, you may want to check the SMD replacement guide here: https://joes-tech-blog.blogspot.com/2018/11/logitech-slimdevices-squeezebox-classic.html

Don't forget that the four shorter TX10 screws are the ones fixing the mainboard inside whereas the two longer ones are applied from the back of the device to hold the front piece of the case.

Finally:

Taking a look at the poor little old display, I noticed a considerable amount of burn-in! See how you can easily read (German) text here?

So that display had the worst form of aging. The pixels covered by the text have burnt so bad they actually went darker than the surrounding ones.

It probably sat around uninterrupted for years, just showing the first step in the setup process. So that Classic wasn't even used most of the time. Why the owner had it plugged in at all remains a mystery.

 

Advice for VFD Display Maintenance

If you like to get more information about VFDs and how they are best treated in operation, you may want to read this article. It discusses failure scenarios and also some advice how to avoid damage in the future.

Final Words

I hope you liked this guide.

If you want to have this repair done for your Squeezebox, feel free to contact me. I am available as JoeMuc2009 in the US-based SlimDevices Forum, or  as JoeMod2015 in the German Squeezebox Forum. Or just drop me a note here in the comments. Or contact me via e-mail to johannesfranke74@gmail.com.

I have collected experience with Squeezebox devices for some years now and can fix more issues than just the displays. Always glad to help so don't hesitate :o)

Cheers,

Joe

 

Legal Concerns

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!