Saturday, December 16, 2017

Logitech (Slimdevices) Transporter Repair Considerations

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Logitech (formerly Slimdevices) Transporter Repair Considerations

Hi all,

apparently more and more of people's Transporters are having problems lately as they are getting around 10 years old. This is to point out the issues and how to solve them.
This is a documentation of my experiences so far with my own Transporter as well as four devices that I had on the table to fix them. So this is certainly not comprehensive or complete but covers popular issues anyway.
The most popular issues I found so far are:

  • (non-fatal) fading displays
  • consequences of a failed front panel power supply:
    • (non-fatal) "dead" displays no longer showing anything while the rest of the unit works
    • (fatal) boot loop
    • (fatal) not powering up at all
  • (fatal) noisy DAC / bad analog output
(non-fatal) means that the unit is still operational and the issue is rather cosmetic.
(fatal) means the Transporter is useless until it is repaired.

Let's get into the details of each.
You will need some tools for disassembly:
  • a 1/16 inch hex bit for the outside screws holding the top part of the case, and, if needed, to separate the back panel from the bottom part of the case
  • a TX10 torx driver for the internal screws holding the board down
If you plan to repair the existing PSU (power supply unit), you will also need:
  • desoldering tool or material like solder wick
  • an appropriate soldering iron (I recommend one with no more than 20 Watts, set at ~320°C)  
  • small diameter heatshrink tubing and a heat gun
  • a hot glue gun
  • some adhesive tape

Fading Displays

Just like any Squeezebox that employs a VFD-type display, the Transporter's displays are also susceptible to the burn-in problem. See here for my blog entry on the Boom that explains the VFD and its potential problems in depth.
Just to add here, the Transporter is also keeping the displays on at all times except when it is unplugged. Many people use the "screensaver" feature to have clock time, date, weather info, or RSS feeds displayed while the Transporter is not busy otherwise. Similar to the Boom, the automatic brightness adjustment exaggerates things a little and tends to put the displays on a rather high brightness level which encourages accelerated pixel burn-in.
This is the main reason for shadows appearing "over" the actual display content. But the VFDs are also aging evenly with the years. Comparing a display that was driven rather softly to a brand-new one will also show that the newer one is overall considerably brighter.
I think it's safe to say that the displays age only while being powered. The filament wires are constantly on even in standby, and even if the displays are configured not to show anything in standby mode. I used to state that the filament can bear this easily but I might be wrong here. I could not explain the overall aging (of all pixels, also the less-used ones) otherwise.
Anyway, after 10 years of constant use the displays will show some form of aging for sure. Enthusiasts will enjoy the result of a display replacement.
There is no blog entry on this yet but a lot of the Boom-related article applies to the Transporter as well in terms of the actual desoldering / removal process of the old displays and setup of the new ones. The housing is totally different of course. I may add a separate article on this when I have time.

Consequences of a Failed Front Panel Power Supply

This is all about the yellowish small PCB between the front panel and the green mainboard in the left half:

This module is switched on by the mainboard through the relays and takes 100-240V AC input to create 5V / 2.3A out of it. This voltage is used to drive the display filament wires as well as part of the front panel circuitry. It's as simple as that: two wires in, two wires out.
Here's a closeup of the module in question:

In my opinion, Logitech made a questionable design choice here. While the rest of the Transporter is state of the art in terms of build quality, this looks like a Chinese 3 US-$ part, really something not up to the quality standard of the unit at all. So it's no surprise this is the most popular point of failure. Probably an afterthought. However, there are three (out of four) screw posts in the Transporter housing which fit the screw holes of the PCB perfectly so this power supply is part of the concept.

Symptom 1: Dead Displays

When you observe that your Transporter is playing music as it used to, so it is fully controllable via LMS in the browser, a Controller, or the infrared controller, but the displays stay dark (and the usual heat they radiate is missing), then this is a pretty safe indication of a failure in the display power supply module.
So one of the failure modes is that the displays stay off while the power supply is apparently still capable of powering the front panel enough to make it communicate to the CPU. In some cases, even the front panel controls (the TransNav knob for instance) are still usable.
The repair options for this are discussed further below.

Symptom 2: Boot Loop

Another failure mode stemming from this PCB is when the Transporter starts with the usual relays clicking and the Logitech / Transporter logos appearing on the displays, then restarting with the same procedure indefinitely. A usable level is never reached, and it is not possible to control the Transporter through IR controller, or LMS. It won't even become visible on the network.
In this case, the power supply board is capable of doing its thing for a few seconds until it collapses. The CPU triggers a reset once the communication to the front panel is lost which will also restart the display power supply board.
The repair procedure is same as for the previous issue so continue below to find out.

Symptom 3: Transporter Not Powering Up At All

If your Transporter stays dark and does not give a single click after plugging in, it's the third failure mode of the display power supply. In this case it has virtually no output anymore, i.e. the front panel has no power. As the CPU checks rather early in its boot sequence for the presence of the front panel's circuitry, it will reset before anything else observable happens. An indication of this failure is the LED that is near the CPU board is blinking permanently. It is usually off and flashes along with infrared commands coming in.

Failure Analysis

I had not taken the chance to get deep into the analysis of the failed boards but the main reason for PSU failure is apparently heat. Everybody who is a little more into fixing Hi-Fi equipment from the eighties or nineties knows that, most of the time at least, issues arise from aged capacitors. Electrolytic capacitors specifically because their liquid or gel electrolyte dries out over the years which lowers their capacity more and more until the circuitry that relies on them can no longer work. Another problem is that the design of consumer appliances is often focused on maximum turnover, i.e. the components used are sometimes not ideal for their place because manufacturers picked the cheapest ones.
Electrolytic caps have three values to be taken care of: maximum voltage, capacity, and maximum working temperature. Voltage and temperature are determined by the surrounding circuitry and it is always a good idea to add some headroom to these values. For instance, if you know the circuitry will use the capacitor in a place where up to 240 Volts may be present, use a capacitor that is specified up to 400 Volts. Because 240 Volts are converted to peaks as high as ~350 Volts in rectification, and the primary filter capacitor is typically placed right as the next component after the rectifier. But also in a pure DC area it is better to pick capacitors capable of handling considerably more voltage than they actually have to in daily life. They will hold up longer because they are never stressed by working at their designed limits.
Likewise, capacitors are often specified for 85 °C temperature where 105 °C would have been the better choice, just to be sure. In switching power supplies, there are multiple components that run pretty hot by nature. If an electrolytic cap is placed in the same region as components running red-hot, failure is guaranteed sooner or later. But using caps capable of handling higher temperatures, you can push the failure further ahead.
In this respect, PowerPAX did their homework, all electrolytic capacitors (all SAMXON branded by the way) are properly rated:

C1: 22µF 400V 105°C
C2a: 680µF 10V 105°CC2b: 680µF 10V 105°C
C3: 470µF 10V 105°C

The output filter caps (C2a+C2b, driven parallel) are 10V rated which is double the output voltage. So far, no obvious reason for why it fails anyway, right?
Let's have a look at the temperatures:


30 Minutes later:


These images are from a good power supply where no failure ever occurred. However, remember that this unit is permanently on, i.e. the components are permanently fed and there is not much room in the Transporter's housing to distribute the heat elsewhere. There are no cooling slots in the housing either, and none of the components has any sort of heatsink. So this may go well beyond the 64.7°C I measured rather early after a cold start. The measurements from 30 minutes later show that the main switching transistor at the top got about 7 °C warmer whereas the other one accumulated 2 °C additionally. This may get worse over time. I would not be surprised if they reach around 100°C at some point.
Let me repeat the layout photo from above for comparison:

While the switching transistor at the top is far away from the big primary filter cap (top right), the second transistor can freely radiate its heat towards the secondary filter caps C2a and C2b. This may weaken them over time.
In one Transporter I found this:

Observe the dark brown region about the Zener diode ZD3, a bit left from the center of the picture. This is a clear sign of excessive heat, and it's in close proximity of C2a and C2b, also not too far away from C3 (indicated just by silk screen on the left, at 45° angle, because I desoldered it).
So the failure may have come from the Zener diode's heat instead of the transistor's. The fact the diode gets so hot must be the consequence of another fault because in my working PSU, this diode is not getting warm significantly at all.
While the capacitors may appear good in direct measurement, my recommendation is to replace them all. That's not the maximum ecological sustainability but these caps are probably already failed or close to failing if the power supply overall fails.
You may also find one or more caps having bulged tops or having risen from the board with bulged sealings at the bottom. A capacitor is designed to fail at the top, hence the little indentations you can see there in the form of a plus sign or three indentations going from the center to the outside. The metal can is thinner along these lines to ensure that they are the defined failure point should overpressure cause a rupture. In this case, (very unhealthy) electrolyte and other stuff shoots out. On a board mounted vertically this is good because the electrolyte will spray in a direction away from the board. However, if the board is mounted horizontally as in the Transporter and many other devices, a blown-up electrolytic cap can hit a large region around it. Therefore it is best not to let this happen at all.
The rupture points also fail sometimes, for instance the bottom sealing may break sooner than the thinned metal lines which causes the electrolyte to leave the capacitor at the bottom. While both failure modes may cause damage, the more severe damage comes from seal failure because the electrolyte is very aggressive and starts damaging the PCB immediately, up to completely destroyed PCB traces in the worst case. It is much more concentrated then due to the little space it has to distribute. If you observe patches with darkened PCB traces and / or dull-looking solder points, that is a pretty safe indication of accelerated corrosion by electrolyte. A UV (ultraviolet) light also helps reveal the electrolyte.
Capacitors showing any of the said weaknesses should go as soon as possible. Again, my recommendation (specifically for this Transporter power supply) is to replace all of them in this case no matter how good they look outside. If you have proper measurement equipment like an LCR meter, you may also desolder the caps and do an extensive check, replacing only the ones having bad values. A thermal camera can help reveal that a capacitor is getting unexpectedly warm which indicates that it does not work properly anymore. They should never "produce" heat in operation.

Fixing the Front Panel Power Supply

Depending on your skills and comfort you can fix the power supply or replace it. I like to be sustainable if possible. Actually the value of the failed parts that need to be replaced is typically no more than 1 or 2 EUR / USD.
The model is a PowerPAX SW3376 and is distributed by RapidOnline. See here for the product info / order site:

You can see there that a single unit costs 8.81 GBP which is around 12 USD (as of 2017-12-15). The module may be available in other countries with other resellers, too.
So many people may wonder why one should bother repairing the unit if the replacement is that cheap. It may also be a consideration that a new module has a completely new life span while replacing single components will leave the rest of the board in its aged state, so trouble may come back.
I have some arguments against that:
  • while a new module has a certain appeal to it, you can be sure that it will fail again within the same time span as the one you discard. The build is the same, and so are the components. The design flaws are still in there and will cause it to fail again.
  • if you are capable of doing a component-level repair, you will be just as capable in case the unit fails again. It's way cheaper than buying the entire PSU as a replacement
  • let's not forget about shipping cost, taxes, customs etc. which will raise the price even if you place a larger order
  • it's kind of wasteful to discard a PCB with about 30 components on it just because three or four of them failed, and replacing them is so easy.
In any case, you will have to remove the PCB so let's start at that:
  • unplug the Transporter from all connections, most importantly from the power line
  • unscrew the outside screws, 4 on each side, with the 1/16 hex bit
  • pull the top cover away from the front. It will slide over the back panel. This may be hard at first because there is really little tolerance in the Aluminum parts, so be sure to push/pull the top cover straight to the back and avoid tilting
  • you will now see what is shown in the very first image above. Locate the display PSU in the left front quarter of the housing
  • oh, by the way, there is a slow-blow glass fuse (500mA / 250V) near the mains connector on the main board. Check it for continuity. If your Transporter is completely dead, and no light at all can be seen, this could be a very simple reason. A blown fuse is cheap to replace and if the next one does not blow, consider your work done. As fuses are also parts susceptible of aging, they can blow at some point with no given reason
  • unplug the wire connector on the display / front side of the PSU
  • the PSU is bolted down with three or four TX10 screws, two near the front and one or two on the other side on the right. Undo these screws. They are not magnetic by the way so even if you have a magnetized screwdriver, the screws will just fall down after undoing
  • now unplug the remaining wire connector
  • when the board is free, it is good practice to short the large primary filter capacitor (labeled C1 in the picture below) because it might give you a high-voltage shock that is actually dangerous. There are multiple ways to discharge it:
    • A typical classic 120V or 230V light bulb is recommended if you have one at hand. With a socket and a bit of wire you can just connect the capacitor's terminals to the light bulb. It will probably not flash or glow at all but after a second or two the capacitor's charge is practically gone
    • You can also use a resistor that is specified for the voltage and can take some more current. Use one of the chunky ceramic ones because the flimsy standard resistors may blow up when overloaded
    • An emergency "poor man's" fallback method, albeit not recommended if you can help it, is to short the capacitor with a piece of metal. Just be sure it is isolated on your end. This may cause strong arcing so try to be as far away from it as you can
  • if you have ordered a spare PSU, you are practically done. Just put the new board in the place of the old one and put the Transporter together. Give it a quick test before you put the top cover back on.
  • if you chose the DIY repair path, desolder these electrolytic capacitors:

  • C1 and C3 are held down by celastic material. C1 can be freed for instance with a blade that you push below it. Don't be too violent because the rectifier diodes are hidden beneath. C3 has little room around it so once it is desoldered, all you can do is pull it out with as much force as needed. If it does not give way at all, make sure the soldering connections are actually free, and try again
A word on electrolytic capacitors: with a few exceptions, they are not bipolar, i.e. they have a negative and a positive terminal and must be placed accordingly! If you reverse them accidentally, they will be destroyed and that's least of the problems. In high-voltage areas, they can blow up violently and cover everything with violent fresh electrolyte. Luckily, the silk screen on the board indicates which is the negative terminal, and capacitors are also marked, typically with a stripe along one side of the body:

The left red arrow points to a small "+" sign on the board. This is not consistent in all places but makes it even easier to recognize the polarity. What you will always find is some sort of marking for the negative terminal which is the black filled half-circle in this case. So this is where the marked end of the capacitor (negative terminal) needs to go. See these images at Google for examples of electrolytic capacitors. They all have a clear indication of where their negative terminal is. If they don't, they are probably not capacitors, or bipolar, anyway not applicable for this repair.
For reference and to remove remaining doubts, here is the polarity map another time (red = +, blue = -)

As we know that capacitors cannot deal well with heat, we have a good chance now to improve the situation. Instead of putting the replacement capacitors back into the same spot, my recommendation is to place them as far away from the board as possible by using the full length of the capacitor's legs. Use shrink wrap to ensure that they do not short with each other or with any other component on the board.
A result might look like this (C3 was not replaced here because it was still good):

There are a few things to consider for this solution:
  • the image shows that the front panel flat flex cable is running across where the capacitors are placed. The original kapton sticky tape is placed approximately where the large black capacitor is now so the tape needs to be moved, or better, be replaced and put in a more convenient region
  • below the PCBs there is a sheet of strong plastic material as an isolation layer. This is stuck down at the left edge but not anywhere else so it can move between the bottom metal shell and the PCB which is mounted on ~5mm posts. As you might place the capacitors on this surface, you should ensure that the plastic sheet is no longer capable of moving. The easiest way to achieve this is to run some lines of hot glue along the edges of the plastic sheet to stick it firmly to the metal bottom shell as shown in the photo in three places in the bottom right corner. This is at least worth considering if the Transporter is not yours and you have to send it via a parcel service. Frequent motion will wear out the capacitor legs as well as the soldering spots they are connected to so we should try to fix them safely in their place, for instance with another blob of hot glue for each to hold it down to the plastic sheet. You will have to undo this whenever you want to service the board next time so before you do this, better run a test to see if it all works as desired.
The image also shows that I did not do a complete replacement. C3 was not replaced at all.
If I had replaced C3, I would have isolated and run its legs towards the left side, and stuck C3 down against the plastic shield there, just like I did with the other capacitors.
Another deviation: for C2a and C2b which are connected parallel anyway, I picked a single replacement capacitor. I think it's 2200µF/16V instead of the original combined 1360µF/10V (2x 680µF). A higher capacity is not actually necessary but I did not have any closer values at hand at the time of repair and it is not too far off the original value. It may be intriguing to pick even higher capacities, assuming that the capacitor will then do a better job of filtering the output and stabilize it. However, a much higher capacity is actually counterproductive here due to the nature of capacitors. A discharged capacitor has a very low resistance while being charged. The higher the capacity, the heavier the load for the circuitry feeding it. This is close to a short which may damage other components again. And as this PSU feeds digital circuitry that is not in the audio path, there is not much use in trying to generate the cleanest voltage here.
While 2200µF is considerably more than 1360µF, we are in a low-voltage environment in this part of the circuitry and 2200µF is not an extreme capacity, so the components feeding the capacitor should be capable of bearing this.

The last steps of the repair process are:
  • ensure the mains power cord is not plugged in
  • plug in the primary connector (from mainboard to PSU board)
  • put the PSU board back in and fix it with the three (or four) TX10 screws. Do not use hot glue yet!
  • we can now test the output voltage of the board. If you connect the power cord now, the Transporter may behave in funny ways because it cannot find the front panel PCB. Ignore that for now. Use a multimeter to measure the output of the front-facing connector on the PSU. It should be 5 Volts or a little more. If your meter reads something far below 5V, like 4.8V or less, or more than 5.5V, that's not a good sign. You should not connect the front panel power connector to it in this case. A new PSU might be the better option after all as there is something else wrong and it's really hard and dangerous (at least for me as a non-expert in this field) to find out what else is wrong in a switching power supply. So many things can go bad that I would not recommend to go deeper into this
  • assuming the output voltage looks good, disconnect the Transporter from power again and set the front panel connector. It is polarity-safe by a "key" in the plug. If you have trouble inserting it, make sure it is the right way around. Don't force the connector in violently because reverse polarity will definitely destroy your front panel PCB and damage might spread to the mainboard through the white flat flex cable
  • it's another test round now. Connect power again. The boot sequence should be as usual now, you should hear the relays clicking and within 5 seconds, the Logitech/Transporter logos should appear on the front displays. If possible, try to measure the PSU voltage output during this phase and see if you can still measure a constant 5V output. If this is not happening, or you notice a smell, smoke, any unusual noise or any other irregularity, disconnect the Transporter from power immediately! It's certainly a good idea to have a switchable power cord or extension that you can quickly disconnect with just the push of a button or switch, rather than having to pull the plug. I really hope you won't be in this situation because it is hard to say what went wrong and how catastrophic the damage actually is. If you followed the instructions closely up to this point, there should not be a reason for this happening. Some advice if the odds are against you anyway:
    • are you sure you took the polarity of all capacitors into consideration? They might fail spectacularly, especially the primary filter cap getting fed in close to 400 volts, if accidentally reversed
    • where did the unusual activity (smoke, fire, noise) come from? If it is the PSU, using a new PSU might still save your day if nothing else was damaged. If anything else blew up, this may mean irreversible damage to your Transporter
    • did you notice any other unusual things about the Transporter in the past? Maybe that is an indication of damage other than just the PSU
  • hopefully your Transporter is now displaying stuff and connected to the source of your choice. If you use WiFi, at least one antenna may have to be connected first for successful network access. Check the front panel controls for functionality, everything should be as usual now
  • put the top cover back on. I suggest disconnecting the device completely again and putting the Transporter face down on your thighs, then sliding the top cover over the back plate. This gives you best control to push it down evenly. Note that the top cover cannot be placed either way as the screw holes are not the same distance on each end. At the front side, the screw holes are a bit closer to the edge then on the back side. If you find that the screw holes do not line up with the threadings beneath, that's a pretty safe indication of the top cover being put on the wrong way
  • put the eight outside screws back in
  • Congratulations!
In my opinion, a repair that covers these aspects is a better outcome than just a new PSU. This solution will last much longer because there is no heat-related stress for the capacitors, and they are what fails most of the time. Just replacing the old board with a new one will give you another ~10 years of Transporter lifetime until it fails again. The construction is still basically the same and it suffers the same design flaws. So even if you lost all confidence in your old PSU board and ordered a new one, it may still be worth while to modify the new board by exchanging the original SAMXON caps with parts of better quality and modifying the PSU to keep the caps away from the board as shown above. This will of course void any warranty you have on the new PSU but if you know what you are doing it should not be a concern. Eventually the loss is around 12 USD if the mod ends catastrophically.

Noisy DAC / Bad Analog Output

This has nothing to do with the display power supply for a change. If your Transporter's analog outputs are dead, or strongly muted and/or distorted, this is an indication of the Digital-to-Analog Converter (DAC) not getting the required voltages.
The Transporter uses two potted toroidal transformers (the blue modules on the far left edge of the mainboard). One generates 2x 18V AC which is converted to +15V DC and -15V DC to give the DAC its reference voltages. If this transformer fails, the DAC cannot work properly.
I found in one case that out of the two primary windings of the transformer, one had gone high resistance; it was not completely open but clearly out of order. The high resistance caused the output voltage of the transformer to drop down to almost nothing.
I don't know for sure but assume that the relays have something to do with voltage detection, and depending on the input voltage, either one winding is employed only, or both primary windings are switched in series. Probably 240V in one primary winding will produce approximately the same output as 120V across both primary windings. The circuitry to determine this cannot be supplied from the transformers but must be connected to some other form of universal power supply. Not sure about all this though.
What is safe to say is that either way, only half of the transformer failing causes it all to fail.
A safe indication of this is when the three LEDs in the analog area of the mainboard (right side, opposite of the transformers) are not lit, just dim, or flickering. They should be reasonably bright. What helps a lot here are the two measurement points for the +15 and -15V reference voltages. Just measure these and if they are not spot-on 15V, there's something wrong in the power rail. I was a little surprised to find that the failure is at such an unusual point as the transformer. But it's actually something that makes the repair way easier than diagnosing tons of SMD components.

Just to be sure, the following instructions apply only if the DAC reference voltages, or one of them, are actually missing. The next steps will only fix this specific issue.

The part you need is a Talema 70014K transformer module. It can be found at RS Components for example:

The part is rather cheap, currently (2017-12-16) it's 10.73 EUR or ~12.60 USD, and it is identical to the original part. Always good to know that original parts are still made.
You can find it on the left side of the following picture:

See below for the repair approach.
  • unplug the Transporter from all connections, most importantly from the power line
  • unscrew the outside screws, 4 on each side, with the 1/16 hex bit
  • pull the top cover away from the front. It will slide over the back panel. This may be hard at first because there is really little tolerance in the Aluminum parts, so be sure to push/pull the top cover straight to the back and avoid tilting
  • you will now see what is shown in the very first image above. The mainboard is the green one in the back of the device
  • to get it out, disconnect the white flat flex cable that goes to the front panel PCB. Use a lot of caution with the PCB connector as it easily breaks!

  • The flat flex cable is fixed in its end position by the brownish top part of the connector. If it is pushed down, it will press against the flex cable, ensuring it cannot slip out. This piece needs to be lifted by about 1mm on each side. The small plastic tabs on both sides look promising but be very careful as they easily break off! This will make handling the flat flex cable miserable. I recommend using a (very) flat screwdriver, a blade, or a spudger, and push it under the tab. Attempt to pull the brown part up from as far "inside" as possible instead of using the plastic tab for it. The following picture is to illustrate, the spudger being the red outline shape, hopefully it makes things a bit clearer:

  • with the spudger or whatever you are using is in this position, carefully lift it with as little effort as possible. It is safer to lift it just a fraction of a millimeter on one side, then doing the same on the other side. This will take some patience but believe me, a broken connector is practically impossible to replace as there are so many different and incompatible forms around. Awesome soldering skills are also required to do this without any damage to the board. If you broke it and consider yourself adept enough to replace it, this is probably (!) a good replacement: - please be aware that I never ordered one of these so I cannot guarantee that this is actually a good fit. It just looks similar and has similar dimensions, considering the pin count and pin pitch. I cannot share any experience about it though so don't hold me liable
  • once the flex cable is out of the way, you will see why this was necessary. One of the 13 TX10 screws that hold the board in place is hidden beneath the flex cable. Bending that out of the way is not a good idea. Disconnecting it will also make the following work way easier
  • remove three 1/16 hex screws at the bottom edge of the back plate to free it from the bottom shell
  • undo all 13 screws on the top side of the mainboard
  • the next bit may be tricky. You may find that the mainboard and back plate are still hanging somewhere so you cannot easily lift them out. The reason is the plastic sheet isolation that has a hole which surrounds a metal bolt (actually I think it is one of the threadings for the screws that connect the back plate and bottom shell) between mainboard and back plate in the region of the big mains connector. Unfortunately, I have never taken any pictures of this location. Anyway, you will notice that the plastic sheet keeps you from taking the mainboard out because it is stuck down firmly along the left edge of the bottom shell. It takes some wiggling and right placement of the plastic sheet to get it free eventually
  • once the board is out, the transformer we need to desolder is illustrated here:
  • so that's eight pins to be desoldered. The transformer will probably just drop out once you desoldered all pins because (thankfully) the pin are straight and were not bent in any direction during production of the board
  • if you are curious, you can now find out which transformer winding gave up. Each pair of pins is connected to one of the coils. All should have a rather low resistance (primary resistance is typically higher than on the secondary side). One is probably just open or has a considerably higher resistance
  • solder in the new transformer. I recommend soldering one pin and then another across. Then check that the transformer is flush on the board with no gap in between. This is corrected more easily if only two pins are fixed. Just heat up the respective soldering point and push the transformer as far towards it from the other side as possible. If it is flush with the board, continue with the remaining soldering work
  • to check now whether the repair is a success, you will have to put the Transporter back together mostly because the mainboard won't power up without the front panel PCB being connected, and also the front panel power supply in service
  • it is too soon to reassemble it all completely so we will do the minimum amount of work now so the unit gets ready for testing
  • put the mainboard back into its place, taking care of the isolation sheet which must be in the same position as it was before disassembly, otherwise it will be hard or impossible to put it back in its position. Do not use force here or bolt it down if you feel there is any physical resistance
  • align the board to its screw posts and fix two or three of the TX10 screws so it doesn't all fall apart. One of these screws should be the position that is later covered by the flex cable. This makes final assembly easier if you find that everything is working as desired. Then, you just need to fix all the other screws and it's finished. Otherwise you may have to disconnect the flat flex another time with the risk of breaking the board-to-flex connector like before
  • push the flat flex cable back into its connector, ensuring that the brown plastic lock stays up and open while you insert the cable. Make sure the flat flex is in its end position and cannot be moved more deeply into the connector. Eventually push the plastic lock down. Again, try to avoid the tabs because they are so unstable. Better apply equal pressure across the entire part. Ensure at all times that the flat flex goes straight down and is not askew
  • reconnect the front panel power supply
  • carefully plug the mains power connector in but stay ready to unplug it in case anything does not go as expected
  • relays should click, and within ~5 seconds, the displays should show the boot logos
  • observe the three LEDs in the DAC area. They should all light up now permanently:

  • the fourth LED not shown in the picture (near the small mainboard stack) should stay off unless you send a command from the infrared remote control
  • to check it completely, connect Ethernet or one of the WiFi antennas and have it play a bit of music. The sound should be crisp and clear as usual now
  • put the top cover back on. I suggest disconnecting the device completely again and putting the Transporter face down on your thighs, then sliding the top cover over the back plate from above. This gives you best control to push it down evenly. Note that the top cover is not identical on both ends as the screw holes are not the same distance on each end. At the front side, the screw holes are a bit closer to the edge than on the back side. If you find that the screw holes do not line up with the threadings beneath, that's a pretty safe indication of the top cover being put the wrong way
  • put the eight outside screws back in
  • Enjoy :o)

Final Words

Legal Disclaimer

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.

Repair Service

In case you would like me to do any of these repairs (including display replacement), just drop me a mail at I have good experience with Squeezebox devices and own a Transporter myself that helps a lot in troubleshooting and comparison. Repairs are done at a fair rate and with warranty on parts and work done.

Thank you for reading!

Friday, September 22, 2017

What's inside a Lenovo Docking Station for ThinkPad Notebooks?

Just another curiosity trip. After all these years of proudly using Lenovo Thinkpad notebooks with docking stations at work and at home, I have always wondered how much hardware these docking stations actually add or contain. Are they just stupid port replicators, adding ports wired 1:1 to that large docking connector, or do they have their own brain?
Let's find out and get right into it. Excuse the image quality, this was done on the fly with little time.

The subject of this blog is a Type 4338 ThinkPad Mini Dock Plus Series 3 with USB3.0, Lenovo part number 0C10039 and FRU part number 04W3939. Used this with my W530 notebook.
To get started, undo five screws at the bottom side. The two dotted arrows indicate two more screws on the connector side of the unit which also need to be removed.

The topside does not offer any screws. Nothing is moving much unless a notebook is actually placed on top of it. To get the connector cover off, push the top left and right hooks inwards and lift it out.


This is how the top cover looks inside, the both hooks are indicated by yellow arrows. Note that the three tabs on the other side are what is coming out last in disassembly and getting in first when you put it back together.

Once the top cover is gone, we find two springs and four more screws (around the connector) which we need to undo to get the shell open.

Oh, did I mention there are two more screws at the backside where the connectors are? The first is above the Kensington lock slot.

The second is in the USB connector section:

We can now begin to separate the top and bottom gently. Notice there is a small ribbon cable for power and lock status that needs to be disconnected. The end of the cable will stay connected to the main PCB in the bottom part.

On the other side of the unit are the microphone and headphone connectors. The upper part of the housing needs to be cranked over them to come loose:

Be careful in this step so you won't damage the connectors or anything around them.
The active circuitry is all in the bottom section, all shielded perfectly Lenovo-style. To get the shielding metal sheet off, remove five silver (yellow arrows) and three black screws (blue arrows):

The metal shield is sitting tight around the notebook connector so you will need to pry a little there. You will also need to undo the nuts holding the VGA and both DVI ports in place. It is indicated in the next picture where the sheet is already gone:

We now see the backside of the PCB beneath the black isolation sheet so it is actually working in upside down position. All the electrons are gonna fall out!
A little wiggle here and there, and out comes the board!

So that's a bit more circuitry than I expected!
The DVI/DisplayPort pairs each have two dedicated controlling ICs:

U104 and U103: Parade PS8312 – 1:2 DP to DP/TMDS Demux

U101 and U102: Texas Instruments SN74CBT3257 4-Bit 1-Of-2 FET Multiplexer/Demultiplexer

Now for the audio interface:

U110: Texas Instruments TPA6132A2 25-mW DirectPath™ Stereo Headphone Amplifier With Pop Suppression

The single USB 3.0 connector:

A little below that:

U501: Single Lane USB 3.0 Redriver . (Rev. A) - Texas Instruments (PDF warning)

So far this is all firmly in the hands of Texas Instruments. Well, why not.
Near the Ethernet connector, we find this fellow:

U111: SMSC (Microchip) USB2517 USB 2.0 Hi-Speed 7-Port Hub Controller

Each of the the paired USB 2.0 connectors are supplied by this combo:

The Ethernet transformer/controller (I never knew this exists as an all-in-one module):

T101: M-Tek G24101SKG (can't find any data sheet on this one, sorry)

Random part probably supplying the DVI/DisplayPort section:

U8: ST ST1S10 Monolithic synchronous step-down regulator

Close to it we find:

Q12 and Q13: ON Semiconductor FDS6690A Single N-Channel, Logic Level, Power Trench® MOSFET

And further below:

U9: 418 1225 G000 (sorry, unknown part)

So what is the docking station? It seems clear that most functionality depends on the notebook. It adds a large USB hub, a USB 3.0 port, an ethernet port which is mutually exclusive with the one built into the notebook, display multiplexers (not a separate video adapter), and an audio amplifier which merely repeats the notebook signals (and is also mutually exclusive with the connector in the notebook).
As there is not much circuitry around the VGA connector, it is probably just passed through from the notebook.

And that's it! Hope you found this interesting :o)

Wednesday, May 24, 2017

Reparatur BMW E39 Celis / Angel Eyes / Standlichtringe (Birne durchgebrannt)


Wenn Euch der E39 mal so begrüßt (siehe linke Scheinwerfer), dann keine Panik. Es ist mit hoher Wahrscheinlichkeit nicht das Steuergerät ausgefallen, sondern das Leuchtmittel, das die sog. "Angel Eyes" beleuchtet, also die Ringe um die Scheinwerfer herum.
  • wenn nur Standlicht eingeschaltet ist, fehlt es auf einer oder beiden Seiten. Statt dessen leuchtet die jeweilige Blinker-Leuchte dauerhaft mit reduzierter Helligkeit
  • die Standlichtringe leuchten auch in keinem anderen Beleuchtungsmodus (Abblend-/Fernlicht)
  • die Blinker-Leuchte wird bei Abblend- oder Fernlicht ausgeschaltet (außer man blinkt tatsächlich)
  • ggf. Meldung "Standlicht prüfen" in Check Control (ohne wäre es mir wohl erst sehr viel später aufgefallen)
Dass dann statt der Standlichtringe der Blinker halbdunkel leuchtet, ist entweder vom Steuergerät so gewollt, um zu zeigen, dass es ein Problem gibt, oder ein Effekt von Check Control, wo vielleicht durch den Ausfall der Birne der Strom sich einen anderen Weg sucht. Ich würde aber eher auf ersteres tippen.

Ich kann jetzt natürlich nur für meinen eigenen E39 touring sprechen, der aus Baujahr 2002 stammt, Xenon-Abblendlicht eingebaut hat, und das E39-Facelift bereits serienmäßig hat. Falls es von Bedeutung ist, es ist ein 530d mit Original M-Sportpaket. Bei meinem werden beide Standlichtringe pro Scheinwerfer von nur einer einzigen Glühbirne beleuchtet. Also nicht eine Kette von mehreren Lämpchen, keine CCFL-Röhre, keine LEDs, nur eine einfache 10-Watt-Glühbirne.
Gemäß Teilekatalog kommt dasselbe Konzept auch in folgenden Baureihen zum Einsatz - ohne Gewähr und ohne Anspruch auf Vollständigkeit:
  • E87 (1er)
  • E63 und E64 (6er)
  • E83 (X3)
Evtl. kann man also die nachfolgende Anleitung auch für diese Modelle brauchen.
Für mich als Nicht-Auto-Schrauber war nicht ganz klar, wie man an diese Glühbirne überhaupt herankommt. Enttäuschend fand ich, dass alle Hilfestellungen im Netz erst anfangen, nachdem die Glühbirne inkl. Halterung aus dem Auto ausgebaut ist.
Darum möchte ich ganz vorne beginnen, um Euch vielleicht einiges an Kummer und Frust zu ersparen.
Vorweg zur Klarstellung: ich beschreibe hier eine auf eigene Gefahr von mir selbst vorgenommene Reparatur. Jeder, der die Anleitung befolgt, macht dies ebenfalls auf eigene Gefahr.  Was ich hier beschreibe, trifft möglicherweise nicht auf jeden E39 zu. Wenn Euer Auto offensichtlich nicht zur Anleitung passt, versucht bitte, die Infos anderswo zu bekommen und probiert lieber nicht herum!
Außerdem übernehme ich keine Verantwortung für Schäden, die durch richtige oder unrichtige Befolgung der Anleitung an fremdem Eigentum entstehen. Ich empfehle ganz klar, diese Reparatur nur mit Vorkenntnissen auszuführen und ggf. lieber eine Werkstatt oder einen erfahrerneren Reparateur ans Auto zu lassen.

Entscheidung: Austausch oder do-it-yourself?

BMW will an dieser Stelle gerne Geld an uns verdienen. Das ist normal, aber hier meiner Meinung nach übertrieben: laut Teilekatalog soll das Ersatzteil 27,09 Euro kosten. Um den Defekt an einer Glühbirne im Gegenwert von vielleicht ein paar Cent oder wenigen Euros zu beheben. Wer dann noch zur Fachwerkstatt geht, ist schnell mindestens das Doppelte los - der Laden muss ja auch Miete zahlen und die Lohn(neben)kosten sind ja so unverschämt.
Der Grund für den hohen Preis ist einfach: es geht hier leider nicht nur um eine einfache marktübliche Glühbirne, eher um ein Modul, in dem eine Glühbirne verbaut ist. Wenn die Birne durch ist, will BMW, dass das gesamte Modul getauscht wird. Geschmackssache! Wer dies hier liest, gehört vermutlich zur Fraktion der Selbstreparierer (zumindest bei Bagatellsachen) und würde sicher erst mal selbst versuchen, das Problem zu beheben. Aber auf für die anderen ist die Anleitung ja vielleicht von Wert.
Das fragliche Modul hat die Teilenummer 63126904048 und besteht aus:

  • dem Reflektor als vorderem Teil
  • der Lampenfassung, die mit dem vorderen Teil an zwei Stellen verschweißt ist (unfair!)
  • der Lampe selbst

Das Modul wird mit dem Reflektor voran im Scheinwerfergehäuse befestigt und auf der Rückseite per Kabelstecker mit der Elektrik verbunden.
Wer sich für den Komplettaustausch entscheidet, braucht von diesem Beitrag lediglich die Aus- und Einbauanleitung des ganzen Moduls und kann die Reparaturschritte dazwischen überspringen. Aber ich kann nur noch mal sagen, dass es sehr verschwenderisch ist, so viel Geld für eine primitive Glühbirne auszugeben, zumal wenn die Reparatur so einfach ist. Das ist ja fast, als würde Apple für ein schnödes Mobiltelefon ohne Extras 700 Euro nehmen... oh.... egal, ich schweife ab.

Ausbau des Celis-Moduls aus dem Scheinwerfer

Ohne Vorerfahrung fand ich schon die Verortung des fraglichen Bauteils nicht einfach, denn der Teilekatalog (z.B. weist schon mal keinen Scheinwerfer aus, der überhaupt so aufgebaut ist. Die meisten scheinen die Celis-Beleuchtung irgendwie integriert zu haben. Ich konnte jedenfalls kein Scheinwerfermodell finden, bei dem die Explosionszeichnung auf ein entfernbares Zusatzlämpchen hinweist.
Insofern habe ich zunächst natürlich auch die falsche Kappe geöffnet, und zwar die, die man von oben nahe der Scheinwerferfront sieht (auf dem nachfolgenden Foto oben in der Mitte). Darunter ist jedoch nicht das Gesuchte. In Wirklichkeit bekommt man den Zugang zum Modul von hinten. Es sitzt ziemlich genau in der Mitte zwischen Abblend- und Fernlicht und eher an der Oberkante des ganzen Gehäuses. In der eingebauten Position zeigt der Kabelanschluss nach unten.
Im folgenden Bild sieht man die Scheinwerferrückseite, der gelbe Kasten markiert den Einbauort des Moduls. Da dies ein linksseitiger Scheinwerfer ist, wird hier das Modul so eingebaut, dass der Anschluss auf der Rückseite nach rechts zeigt. Auf der rechten Fahrzeugseite zeigt der Anschluss in eingebauter Position hingegen nach unten (siehe ggf. die Bilder ganz am Ende des Posts)

Um das Modul aus dem Scheinwerfergehäuse zu bekommen, dreht man es mit Hilfe der zwei Kunststofflaschen, die aus dem vorderen Teil nach hinten herausstehen, ca. 1/8 Drehung gegen den Uhrzeigersinn. Die Laschen dazu einfach leicht zusammendrücken und das Modul um die eigene Achse drehen. Hier kann sanfte Gewalt erforderlich sein, weil das Modul mit einem Dichtungsring im Scheinwerfergehäuse sitzt. Da ist also einige Reibung zu überwinden.
Die besagten Laschen sind in den Fotos weiter unten deutlich zu sehen.
Bitte an keiner anderen Stelle die Drehbewegung auf das Modul geben! Auch wenn der Kabelanschluss verlockend aussieht, er ist viel zu labil und wird dabei wahrscheinlich brechen.
Das Modul lässt sich am Ende hoffentlich vollständig nach hinten herausziehen. Nun müssen wir das Kabel lösen.
Der KFZ-seitige Stecker ist auf den Anschluss aufgeschoben und wird mit folgender Rastnase gesichert (hier Seitenansicht):

Der Stecker ist mit einem länglichen U-förmigen Clip an dieser Nase eingerastet. Der Clip muss an der gezeigten Stelle leicht angehoben werden, z.B. mit einem dünnen Schlitzschraubendreher oder etwas ähnlichem. Hierbei gleichzeitig den Stecker abziehen, das sollte mit vorsichtigem Krafteinsatz möglich sein:

Überprüfung des Moduls

Bevor Ihr jetzt zu den nächsten Schritten geht, empfehle ich das Durchmessen der Einheit. Es gibt im Verbinder nur zwei Metallkontakte, die direkt zur Glühlampe führen, und die man leicht mit einem Multimeter oder Durchgangsprüfer (Baumarkt max. 10 Euro) auf Widerstand prüfen kann:

Wenn ein messbarer geringer Widerstand vorhanden ist, oder der Durchgangsprüfer positiv anschlägt, ist die Glühbirne in Ordnung! Dann lohnt sich auch kein Austausch. Möglicherweise ist dann doch das Steuergerät betroffen.
Nur wenn kein Widerstand gemessen wird (OPEN, OL oder ähnlich), dann ist die Birne wirklich hin.


Zum Nachbestellen würde ich Euch gerne direkte Links geben, aber es ist einfacher, bei Google einfach nach "ba9s 12v 10w" zu suchen. Es gibt derzeit (Stand 20.05.2017) Wucherpreise bis 34,50 und auch wenn "Automotive" oder "speziell für Angel Eyes" draufsteht, ist der Preis eher Abzocke - dafür weiß man dann zwar, dass man definitiv das Richtige kauft, aber so teuer muss es trotzdem nicht sein. Ein realistischer Preis ist zwischen 3,80 und ca. 5 Euro pro Stück.
Ein paar Beispiele für konkrete Artikel, die man ebenfalls via Google finden kann:
  • Osram 64113
  • Philips Vision H10W
  • Bosch 1987302233
  • Scharnberger + Hasenbein 81837
  • Barthelme 01641130
  • Herth+Buss 89901165
Leider ist es relativ unwahrscheinlich, dass so ein Leuchtmittel noch beim Laden um die Ecke erhältlich ist. Die Kombination aus Bauform, Leistung und Spannung ist zu speziell, am ehesten wird man bei Großsortimentern fündig (eBay, Mercateo, Conrad o.ä.)

Überlegungen zur Umrüstung auf LED

Viele überlegen an dieser Stelle, gleich auf eine LED-Beleuchtung umzusteigen, vor allem wegen der umfangreichen Farbwahl von kaltweiß bis ultraviolett, aber auch wegen der Langlebigkeit. Darauf gehe ich hier mangels Erfahrung nicht im Detail ein. Relativ sicher bekommt man mit billigen LED-Ersatzlampen Probleme, da Check Control sie nicht erkennt und weiterhin Fehler meldet (der Durchgangswiderstand von LEDs ist anders als von Glühlampen, und die Polarität muss auch stimmen, was bei Glühlampen egal ist). Amtliche LED-Nachrüstsätze kosten um die 100 Euro und enthalten dafür zwei Module, die die bisherigen Module komplett ersetzen (also nicht nur das Leuchtmittel).
Bei mir ist nun die erste Standlichtbeleuchtung nach 15 Jahren ausgefallen. Insofern stellt sich die Frage, ob Langlebigkeit ein gültiges Argument für die LED ist. Immerhin entsteht durch die Beleuchtung, egal welche Ausführung, einiges an Hitze. Die Glühlampe kann damit recht gut umgehen, eine LED aber nur begrenzt. Wenn sie zu heiß wird, ist sie gleich wieder defekt. Man muss also schon eine LED-Lösung nehmen, die die Kühlung mit einbezieht. Das macht die Nachrüstmodule auch so teuer, sie bestehen zum großen Teil aus massivem Metall, um die Wärme zuverlässig abzuführen. Ein Ersatz in Form einer LED-"Glühbirne" wird recht schnell versagen, weil das Kunststoffgehäuse so gut wie keine Wärme abführen kann.

Zerlegen des Moduls

EDIT 2017-12-10: es gibt bei Youtube ein neues Video mit einer cleveren Idee, wie man das Leuchtmittel ohne Zerlegung des Moduls herausbekommt! Suchbegriff: GDApyupw_1Y
Der Trick ist, für die beiden Bajonett-"Nippel" an der Glühbirne jeweils zwei kleine Löcher in den Reflektor zu brennen. So bekommt man die Glühbirne ohne Probleme heraus und die neue hinein.
Dies ist sicher die bessere Methode, weil damit das Brüchige Plastik des Gehäuses geschont wird. Dann passiert nicht so ein Unfall wie ich ihn weiter unten beschreibe.
Wer die Youtube-Anleitung befolgt, kann beim Abschnitt "Reflektor reinigen" weiterlesen.

An beiden Seiten seht Ihr jeweils eine runde "schraffierte" Fläche, dies ist die Verschweißung des Reflektors mit der Lampenhalterung. Die ist in den folgenden Fotos bereits entfernt, aber zur Verdeutlichung der Positionen trotzdem:

Da das Gehäuse aus Plastik ist, lässt sich die Verschweißung recht leicht aufmachen. Ich habe dazu einfach eine kleine Kneifzange genommen und jeweils seitlich an dem Steg, den man unterhalb der verschweißten Stelle sieht, entlanggeschnitten - er setzt sich bis unter die Schweißstelle fort. Das Plastik ist recht hart und etwas spröde und lässt sich gut schneiden. Wegen Bruchgefahr sollte man aber vorsichtig sein und lieber mehrmals kleine Schnitte machen.

Die beiden Teile sollten am Ende nicht mehr ganz fest miteinander verbunden sein, sondern leicht wackeln. Die Verbindung ist dank des inneren Dichtungsringes immer noch recht stark, lässt sich aber nun auseinanderziehen. Bitte hierbei möglichst nicht verkanten, weil dann der Kragen des Reflektors bricht, in dem der Lampenfassungsteil eingeschoben ist (dazu mehr im nächsten Abschnitt)

Übrigens, wer jetzt denkt, das sei ja unglaublich umständlich, und die Birne ließe sich doch einfach nach vorne herausziehen (quasi durch den Reflektor hindurch), der irrt: die BMW-Ingenieure haben sich ein teuflisches Detail ausgedacht, und zwar handelt es sich bei der Glühbirne um eine mit sogenannter Bajonettfassung, d.h. sie hat am Anschlussende zwei seitlich herausstehende Noppen, die in der Fassung einrasten. Die Öffnung für die Birne im Reflektor ist gerade so groß, dass der Glaskörper der Birne hindurchpasst, aber eben nicht die breiteren Noppen. Auch mit Verkanten ist das nicht ohne Gewalt möglich und man würde den Reflektor beschädigen. Daher bleibt tatsächlich nur das komplette Zerlegen.

Gehäuse prüfen

Der Gehäusekunststoff PEI oder Polyetherimid (Wikipedia), aus dem unser Modul besteht, steht im Betrieb unter einer ziemlichen thermischen Belastung. Die Glühbirne wird mit 10W Leistung recht heiß, und der Kunststoff leidet darunter, trotz der Hochtemperaturfestigkeit, die man PEI attestiert. Das zeigte sich bei meinem Exemplar leider mit einem Riss, nicht ganz sicher, ob er schon vorher da war oder erst durch das Zerlegen entstanden ist:
oh f...
Der Riss fängt beim linken Pfeil an (das ist leider schon hinter der inneren Dichtung) und zieht sich bis zu der Kerbe durch, an der früher die Verschweißung war.
Das kann bei Euch ähnlich aussehen. Diese Stelle steht durch den von innen drückenden Dichtungsring ziemlich unter Spannung und das Material wird ständig aufgeheizt und kühlt wieder ab. Da ist es leider nicht zu vermeiden, dass der Kunststoff irgendwann spröde wird.
Wenn ja, steht Ihr vor der Entscheidung, ob es nun doch Zeit für ein Neuteil ist, oder ob der Schaden noch reparabel ist. Je nach Ausprägung des Risses kann eine Reparatur noch möglich sein.
Da es sich hier um kein lebenswichtiges Teil des Autos handelt, reicht mir ein Kabelbinder, den ich einmal außen herum festziehe, nachdem alles wieder zusammengesetzt ist. Nicht vorher, denn ohne "Füllung" den Kragen zusammenzudrücken kann zu einem neuen Riss oder gar Bruch führen. Den Riss kann man mit Sekundenkleber oder Heißkleber auffüllen.
Sollte aber der Riss nicht der einzige sein, so dass vielleicht schon Teile des Gehäuses komplett abbrechen, dann kommt man um den Neukauf wohl kaum noch herum.

Defekte Birne entfernen

Hier nun die Draufsicht auf die Fassung. Die Birne kann man leicht in die Fassung hineindrücken und dann ca. 30° gegen den Uhrzeigersinn drehen, um sie zu lösen.

Und hier ist der Übeltäter: Philips, made in Germany, 12V 10W, offenbar explosionsartig durchgebrannt, wenn man die Schwärzung am Glaskörper so anschaut:

Fassung reinigen

In den offenen Stellen des Moduls sammelt sich über die Jahre, wie an so vielen Stellen im Motorraum, ein Mix aus Dreck und Öl. Daher ist die innere Dichtung zwischen Fassung und Reflektor wohl auch eine ganz gute Idee, denn gerade diese Dichtung hat einiges eingesammelt, was nicht bis in den Bereich des Reflektors vorgedrungen ist. Es kann nicht schaden, alles gründlich zu reinigen. Bitte bedenkt aber, dass wir hier mit einem Teil arbeiten, das später an der Elektrik hängt. Auf eine nasse Reinigung sollte deshalb eine gründliche Trocknung folgen. Wie weit sich das wirklich lohnt, muss jeder selbst wissen. Mir hat es genügt, den inneren Dichtungsring sauberzuwischen, der Rest außerhalb davon wird eh früher oder später wieder dreckig.

Reflektor reinigen

Der Reflektor ist möglicherweise beschlagen. Es lohnt sich, ihn mit einem weichen Tuch und etwas Wasser, bei schwereren Verschmutzungen mit hochprozentigem Alkohol zu reinigen. Bitte auf keinen Fall einen Topfkratzer, Ajax-Pulver oder Nitroverdünnung nehmen, danach kann man den Reflektor sicher wegwerfen. Es handelt sich hier lediglich um beschichteten Kunststoff und entsprechend zärtlich will das Ganze behandelt werden!

Neue Birne prüfen 

Vor dem Einbau der neuen Birne empfehle ich, diese ebenfalls mit dem Multimeter, Durchgangsprüfer oder an einem Netzteil (max. 12 Volt) durchzumessen bzw. zu testen. Diesen Halogenlämpchen sieht man oft nicht an, ob sie eine Unterbrechung irgendwo haben. Ihr wollt ja nicht erst nach der ganzen Arbeit des Zusammenbaus feststellen, dass alles umsonst war, richtig? Zumal wir gleich noch Sekundenkleber o.ä. einsetzen, was die nächste Demontage etwas schwieriger machen wird.

Neue Birne einsetzen

Zum Einsetzen führt Ihr die Birne in die Fassung ein. Dabei müssen die Bajonett-Noppen bereits richtig ausgerichtet sein, die Führung ist klar zu erkennen als Unterbrechung in dem Metallkragen der Fassung. Wenn nur noch ungefähr der gläserne Teil der Birne herausguckt, ist die Feder im hinteren Teil der Fassung zu spüren. Gegen diese Feder leicht drücken und dabei die Birne im Uhrzeigersinn drehen. Sie muss sich drehen lassen, sonst ist sie evtl. noch nicht tief genug in der Fassung. Nach ca. 1/6 Drehung geht es nicht mehr weiter und sie sitzt nun sicher in der Fassung. Zur Sicherheit noch mal leicht ziehen, es sollte sich nun nichts mehr bewegen und die Birne sollte sich auch nicht in irgendeine Richtung drehen lassen.

Reflektor und Fassung wieder verbinden

Wir schieben nun die beiden Einzelteile des Moduls wieder zusammen. Hierbei gibt es einen bösen Fallstrick, denn es ist nicht egal, welche der zwei möglichen Varianten man wählt.
Der Reflektor hat vorne drei Rastnasen, die im Dreieck angeordnet sind. Damit ist das gesamte Modul im Scheinwerfer befestigt. Über die Position kann man ermitteln, was "Oben" und was "Unten" ist. Eine der Nasen ist kleiner und fast rechteckig, und diese markiert die Oberseite des Moduls, die anderen zwei sind angeschrägt und größer:

Hier noch mal ein geklautes Bild zum Thema. Auf die obere Rastnase zeigt der orangene Pfeil, auf die unteren beiden und auf den nach unten zeigenden Sockel für den Kabelanschluss zeigen die gelben:

Bitte beachtet also vor dem Zusammenstecken schon unbedingt darauf, dass die zwei großen Rastnasen und die Öffnung des Anschlusses auf derselben Seite liegen, dann kann nichts schiefgehen. Es muss einfach so aussehen wie im Bild.
Für die Verbindung beider Teile hat man nun mehrere Optionen, z.B. Heißkleber, oder man lötet beide Gehäuseteile mit dem verbleibenden Kunststoff wieder zusammen. Beides wird aber nicht unbedingt halten. Auch das leidige Temperatur-Thema sollte berücksichtigt werden. Für das Zusammenschweißen beider Teile fehlt nun eigentlich die Substanz, und Heißkleber verflüssigt sich vielleicht, nachdem die Lampe einige Stunden im Betrieb ist und ihre Hitze an das Gehäuse weitergegeben hat.
Sekundenkleber oder Zweikomponentenkleber verbindet beides bombenfest, macht allerdings die nächste Reparatur praktisch unmöglich. Wieder muss man sich die Frage stellen, wie wahrscheinlich ein erneuter Ausfall der Glühbirne vor dem endgültigen Ableben des Autos ist. Durch die gemachte Operation haben wir jetzt einmal gut 20 bis 25 Euro gespart. Wenn die Sache hält, ist alles gut, andernfalls gibt es notfalls immer noch die vom Hersteller vorgesehene Lösung.
Ich habe mich für die Variante Sekundenkleber entschieden, aber das muss jeder selbst wissen. Letztendlich heißt es beim nächsten Ausfall eh "ab zum Freundlichen" und es so machen, wie BMW das schon immer wollte.
Bei mir ist nun auch wegen des Risses folgende Konstruktion herausgekommen:

Die Kabelbinder sind bis zum bitteren Ende festgezogen und Sekundenkleber macht den Rest. Wenn das nicht hält, weiß ich auch nicht...
Den Sekundenkleber lass ich trotz seines Namens lieber eine halbe oder volle Stunde trocknen. Jeder, der schon mal Sekundenkleber an den Fingern oder anderswo hatte, weiß, das ist es wert.

Wiedereinbau ins Auto

Kaum der Rede wert, aber trotzdem: eingebaut wird das Ganze so:

Reflektor bis zum Anschlag (nicht weit) in das Loch, am Ende gibt es wegen des Dichtungsrings möglicherweise etwas mehr Widerstand:

Dann mithilfe der Laschen nach rechts drehen, bis das Ganze einrastet, fertig:

Bissl unscharf, sorry...
Der Anschluss + Stecker sollten jetzt wieder genau nach unten zeigen.
Noch mal als Übersicht:

Und zum Vergleich hier noch ein Bild vom linken Scheinwerfer:

Wie schon erwähnt sitzt hier das Leuchtmodul mit dem Anschluss nach rechts in der Fassung. Ansonsten dürfte der Reparaturvorgang auf dieser Seite sehr ähnlich sein.

Wer bis hier gekommen ist: danke für's Interesse und viel Erfolg bei der eigenen Reparatur! Sollte die auch schon beendet sein: herzlichen Glückwunsch!

P.S.: und wie Murphy so will, passen die Farben jetzt nicht zusammen. Sprich: die neue Lampe leuchtet deutlich "kaltweißer" als die alte (wobei es immer noch ein Warmweiß ist, aber eben heller).
Also Freunde perfekter Optik müssen sich drauf einstellen, dass sie beide Seiten zugleich reparieren müssen ;o)