I hear and read more and more often about electrically folding exterior mirrors that no longer work properly on vehicles from the German manufacturer with the four rings. The problem occurs with many models that have been in service for a few years and are operated in our local climate. In Internet forums you will find some users who know this problem. Also in my circle of acquaintances there are a few rings drivers who have a stuck electric exterior mirror. As a solution, the manufacturer always recommends replacing the entire unit. If you don’t want to spend your savings pointlessly on newly produced residual waste, you can take on this problem yourself. There is even a fairly small cause that causes this problem. And best of all – it can be repaired without any material costs. The longevity of the repair has also been proven…
The error manifests itself through the following behavior:
the mirror makes squeaking, creaking noises when folding in and out
the mirror stays in the wrong position and can only be engaged by moving it manually
the folding behavior depends on the weather
There are many posts about this with possible causes – from defective motors and defective door control units. The best thing to do would be to replace the mirror unit right away and get a new door control unit – yes, of course…
The solution to the problem is simpler: a small steel bolt that is supposed to be pushed out by a small spring gets stuck in its guide. The mechanical part of the mirror is of course also exposed to the environmental conditions and so the area comes into contact with rain, splash water – in winter salt water. Over time, the lubricants lose their properties or are even washed out and the whole “work” becomes stiff. So what helps? Completely disassemble, clean, re-lubricate and reassemble.
For this almost one and a half hour operation, I started by removing the mirror from the door and examining it in the cozy workshop. The easiest way to do this is to remove the inner lining of the door (depending on the vehicle, a few screws and many clips…) The mirror is then connected to the door control unit with a cable and secured with Torx screws.
The easiest way to click out the mirror glass is to use a plate lifter (suction cup). Then carefully – if present – pull off the two flat plugs from the mirror heating (it is essential to hold the contacts on the heating foil against). Next, both plastic halves of the mirror housing can be removed. A little observation helps here, which screws to remove and how the halves are held together.
Now the core of the mirror is there. The two die-cast parts are connected to each other via a hollow axle. The connection cable to the mirror adjustment drive and to the heater runs through the axle. A large steel spring sits above the axle and is attached with a spacer and a clamping ring (I don’t know if that’s the correct term). The spring exerts a fair amount of pressure between the two parts – and this is now the only slightly trickier part – the spring has to come out. To do this, the clamping ring must be levered out while the spring is held under tension. It comes out easily – but putting it back in becomes a challenge if you don’t have the right tools.
The already relaxed spring can be seen in the picture. Now the two parts can be taken apart.
Here the parts are to be recognized in disassembled form. In order to reach the Corpus Delicti, the small gearbox with the motor must be unscrewed. Underneath you can see the bolt, which in this case was stuck firmly in its hole so that the spring was no longer able to push it out.
Cover of the small gearBolt can be seen to the left of the mounting hole
Bolt with springthe guide of the bolt must also be cleaned
The procedure is quite simple – clean everything, remove the corrosion and re-grease with lubricants. After that reassemble everything rejoice. Most of the time of the whole job is cleaning.
By the way: the mirror described here comes from an A5…
When summer comes, new ideas come. In the summer months, as is well known, the duration of sunshine is longer and the intensity of the sun’s rays is higher. Many use this property of the sun to boost their body’s vitamin D production, while others lie under the source of radiation to darken their skin color due to the high UV component. This, in turn, supposedly increases their attractiveness and stimulates hormone production and the willingness to mate… Unfortunately, the non-visible UV range in the spectrum of sunlight is known to have negative effects on the human body. Sunlight can also be used technically. On average, the power of the sun per unit area is assumed to be 1000W per m². Large-area P-N junctions in semiconductor materials are now able to generate electrical energy with an efficiency of up to aprox. 22%.
But the energy can also be used in other ways, or the UV component. Many retro collectors are certainly aware of the problem with yellowed old plastic cases. In order to get this under control, or to get it back to its original state from 30 or 40 years ago, you use H2O2, i.e. hydrogen peroxide and UV light, to get a bleaching process going. And so I came up with the idea for the following project.
At an online electronics store I found a UV sensor board from the manufacturer Waveshare in the sale. On it is a LITEON OPTOELECTRONICS LTR390 chip including a level shifter circuit. An I²C bus is available as an interface. A look at the data sheet revealed to me that the sensor records two wavelength ranges and outputs them separately. The ALS (Ambient Light Sensor from 500-600nm) and the UV (Ultra Violet range from 300-350nm). You can quickly make a simple logging board with this – I thought to myself. So I figured the board should be able to do the following:
Powered by a 18650 cell or USB
USB should also be able to charge the battery
a micro SD slot for recording the sensor data
an RS-232 port for direct logging on the PC
a cool OLED display
two buttons to operate the logger (interval, start/stop etc.)
The control should of course once again take over a chip from Atmega – the 328er. There are just enough of these in my assortment of boxes. To give you a quicker overview of the structure, I drew the following block diagram:
In the next step I created a circuit diagram from the block diagram in order to be able to create a layout out of it. Parallel to the creation of the circuit diagram, I also connected the single components together as a test using “air cabling” and tested whether everything worked as I imagined. And above all, everything should have space in the flash memory of the microcontroller.
The “airy wired” structure consisting of finished components can be seen in the picture above. An Arduino was sufficient for the first tests with the sensor and the OLED display. This enabled me to test the desired functions. So nothing stood in the way of creating the circuit diagram. An 18650 lithium cell will serve as the primary power source. Alternatively, there will also be a USB port that can charge the cell or operate the sensor. Because I’m lazy and component delivery bottlenecks are also a big problem at the moment, I use a ready-made Wemos D1 mini board to charge the battery. Like the OLED display board and the sensor board, this will find its place as a finished component on the circuit board design. As already mentioned, an Atmega328 in a TQFP housing is used as the controller. This will communicate with the OLED display (SBC-OLED01 with SSD1306 controller) and the LTR390 UV sensor board via the I²C interface. OLED and sensor are 5V compatible. However, the SD card is operated with 3.3V. For this, the circuit requires a voltage converter from 5V to 3.3V for the supply and a level shifter for the SPI data bus, via which the SD card exchanges data with the Atmega. Since the Atmega then also wants to be programmed with its firmware, I have provided a 2×4 pin header for connecting a programmer. The programmer needs six of these pins (GND,5V, MOSI, MISO, SCK and RESET) and the two remaining pins are intended for the serial interface. The two interrupt inputs of the Atmega are each wired with a button, which then makes the software operable. The battery voltage is measured and logged via a divider at one of the ADC inputs. The result of these thoughts is the following schematic:
A layout is then the next step. With a size of 12 x 4.5 cm, the circuit board is reasonably “handy”. The printed conductors are routed on both sides and the modules (charging circuit, display and UV sensor) are designed to be pluggable via pin headers.
The two images above show the preview of the “Top” and “Bottom” side of the layout. A circuit board could be created from the production data created in this way.
After some soldering work the hardware was ready. In order to breathe life into this “soldering” , software was required to do its work on the microcontroller.
When tinkering with the software, I used the free “Arduino IDE” development environment. The LTR390 documentation describes exactly which registers are used to operate which sensor functions. But there is also a ready-made library for those who are very comfortable – just like for almost all sensors and actuators that are to be connected to microcontrollers. In the Arduino IDE you can find the “Adafruit LTR390 Library” via the board manager, which you can use to communicate easily with the sensor. In my case, the OLED display is controlled by the SSD1306Ascii library. The “Wire” and “SPI” library take over the bus communication and the “SD” talks to the SD card. The includes then look like this:
I’m happy to post the entire code here if needed. However, it is not rocket science, but simple and certainly not optimized lines of code writing In the current code (firmware) version 1.3d there is a small selection menu that makes it possible to set the log interval of the SD card recording and of course the start or stop recording. It is logged in a text file. The data recorded are UV index, ambient brightness and battery voltage.
This data can now be processed very easily and displayed graphically. As an Office user, you can use Excel, for example, and import the data there and display them as graphs. But it is even easier and also very fast with tools like Matlab. With a script like the one below you can visualize the log file.
If the script is executed, you get a plot that visualizes the measurement data.
The technical information on the sensor can be found in the manufacturer’s data sheet. Here are a few key points:
The LTR390 consists of two photodiodes, one for the visible spectrum of light and one that is sensitive in the UV range. The photodiode current is digitized in internal ADCs. An internal logic controls the ADCs and the connection to the outside world is established via an I²C interface. The resolution of ALS and also UVS can be configured in 13, 16, 17, 18, 19 and 20 bits. The sensor chip is housed in a 2x2mm 6pin package. The detector opening has an edge length of 280×280 µm.
Source: LTR-390UV data sheet https://optoelectronics.liteon.com/en-global/Led/LED-Component/Detail/926Source: LTR-390UV data sheet https://optoelectronics.liteon.com/en-global/Led/LED-Component/Detail/926
Again and again I look for simple, interesting things. This time I was fascinated by a measuring device or rather “display device”, whose operating principle is extremely simple and yet very effective. In addition, from my point of view, it is also an eye-catcher – it is the so-called Goethe Barometer. The best-known form is probably the bulbous glass hanging on the wall with a beak, similar to a watering can, in which the water level indicates the air pressure. I found a slightly differently constructed version of this glass on the net…
A little about the history of this structure:
To a gentleman named Evangelista Toricelli (1608-1647), an Italian physicist and mathematician, we owe the knowledge and proof that the air pressure is subject to fluctuations. He built the first barometer named after him in 1643. In 1644 he developed the mercury thermometer.
A small compensation area in the indicator tube protects against overflow
Der deutsche Dichter Johann Wolfgang Göthe, beschäftigte sich auch mit den Naturwissenschaften. Er machte selbst viele naturwissenschaftliche Experimente und entwickelte später ein einfaches, aber wirkungsvolles Barometer auf den Grundlagen des Toricelli.
Die Funktionsweise:
The barometer shows air changes quickly and precisely. When the air pressure rises, the water column in the indicator pipe falls and when the air pressure falls, it rises. This is made possible by the air trapped in the glass. The volume of the air always remains the same at a constant temperature. If the external air pressure rises or falls, the trapped air is compressed or expanded via the water column. Since the water cannot be compressed, it is the ideal medium to make the pressure differences visible. The height of the water column thus indicates the air pressure. If the air pressure is high in good weather, the external pressure is higher than the pressure of the trapped air and the water column decreases as the trapped air is compressed. At low air pressure, it can expand and the level of the water column increases.
the height of the water level in the pipe indicates the air pressure
This short time-lapse video shows the change in the water level when the air pressure changes:
This time again a quick article on the subject of “Aging and Homematic Smart Home”. It’s about the following device: The Homematic smoke detector HM-SEC-SD, i.e. the older version of the smoke detector from eq3.
First of all: This article only shows how I put this device back into operation. Since it is a safety-relevant device, an acceptance test by a certified testing company would have to take place after the repair in order to be allowed to continue using it. So the contribution only provides what has become broken in the device.
So what is it about? The radio smoke detector HM-SEC-SD showed the following symptom during the monthly test (yes, you should press the test button once a month):
A short press on the button and there was no acoustic signal – instead the red signal LED flashes several times at approx. 0.5s intervals. Replacing the batteries does not change anything, the behavior remains the same. The radio module of the detector behaves normally. It can be reset and taught again. In this case, a look at the operating instructions (under point 9.2 on page 24)
– If only the LED starts to flash after pressing the button, the smoke detector is defective and must be replaced
So time to open the detector and take a look. My first suspicion fell on the detector chamber and that there is contamination here or that an animal has settled in the chamber …
Smoke detector opened
But after removing the lid of the detector chamber, no animal intruders were to be found. However, a strange pattern could be seen on the inside of the lid:
Streaks on the inside of the detector cover
These streaks, I thought at first, were created during the injection molding of the plastic component and must be like that. But on closer inspection and a “wipe” with your finger, they could be removed. In short, these streaks are dust particles. And when they are on the lid, then also in the entire measuring chamber. So blow it out with compressed air, put the cover back on and test it. -> same mistake as before. So again, put the lid down and take a closer look with a magnifying glass. The coarser dust, if you can speak of “rough”, was gone, but the surface of the photodiodes still had very fine and difficult to see streaks. So I cleaned the chamber and the diodes with a little alcohol on a cotton swab.
thorough cleaning required
Another function test showed success – better partial success. After pressing the test button, the piezo squeaked – but only very, very quietly – and by that I mean barely audible and the LED flashed nine times at an interval of one second. So actually the way it should be. Just way too quiet. So something had to be broken. So I examined the circuit starting with the piezo and quickly found what I was looking for. The piezo is controlled by a 40106, a 6-fold Schmitt trigger. In order to get enough electricity, three “Schmitts” are connected in parallel. The output was low-resistance, which is actually not allowed to be. So unsoldered the 40106 and measured it again. Between pin 1, 2 and 7 (input and output of the first Schmitt trigger and the VSS pin) there was a full short circuit. That means the IC is defective.
6times Schmitt trigger IC 40106
After the IC was exchanged, the smoke detector could finally “scream” again as usual.
I have another small contribution to make on the subject of “Aging and Homematic Smart Home”. Many thanks to Fritz for the preparation and analysis.
As in the last post “Homematic actuator quick repair”, this time it is again about a device from the Smart Home series. It is the dimmer actuator with the designation “HMW-LC-Dim1L-DR”. This is a phase control dimmer actuator for incandescent lamps and low-voltage halogen lamps with conventional transformers. Many modern LED lamps can also be controlled with this dimmer. The actuator belongs to the “wired” series, which means that it is not connected to the CCU via the BidCos radio protocol, but via the RS485 bus. The actuator receives the power supply for data communication from a 24V power supply unit. This also supplies the µC in the actuator. The network side is supplied with control data from the low-voltage side via an optocoupler. This ensures galvanic isolation. On the network side there is a dimmer controller module, which in turn controls the triac. This controller must be supplied with a voltage of approx. 15V. To generate this, the manufacturer has built in a capacitive voltage divider. And this is where the aging problems begin …
The error pattern manifests itself as follows: The connected light source cannot be dimmed or switched on. However, the dimmer is communicating correctly with the bus. The red function LED lights up correctly. The commands for “Off” and “On” via buttons are also displayed in the CCU.
Circuit diagram of the mains side on the “main board”defective 330nF X2 capacitor
The cause: According to the data sheet, the IC U2008, a dimmer control module, is supplied with a voltage of DC 15V. In this case, the supply voltage was significantly lower (at approx. 5.8V). This supply voltage is made the 330nF / 275V X2 capacitor C4. The capacitor is optically in perfect condition, but a simple capacitance measurement quickly shows that nothing fits here. The capacitor C4 only had a capacity of approx. 30-40nF. So it’s like so often -> It was the capacitor: D
Dimmer module side view
After the replacement, the voltage on the U2008 was ok again and the dimmer is doing its job again. As a preventive measure, the two other X2 capacitors on the board (C1 47nF / 275V and C2 100nF / 275) were replaced.
Behind the title mentioned in the article headline is my idea of tidying up the “ingmarsretro” blog and tidying it up a bit. By “cleaning up” I mean checking the individual posts again for spelling errors, maybe reformatting one or the other post and adding to it. That is why there will be no other contribution in January 2021.
There are also plenty of new posts that are digitally saved on the server, but there is no paper version of them yet. So I want to put all the posts that have been created since the last backup back on paper in the form of a book. And unfortunately that is not done in a jiffy, but requires a lot of work. The job and the “family time” with my little son only allow me to work on the contributions mostly at night. And between the posts I also work on the projects (little projects) that I then write about. I also have a lot of them in my head that may one day be realized. And then there are some that I’m working on that are still to be completed, or at least should be continued.
For the last few months I have been working on a Nixie clock that should be set up fairly discreetly. The watch has meanwhile also achieved a reasonable status, so that circuit boards from self-etched prototypes to reasonable, industrially manufactured condition have been created here.
the Nixie clock prototype
The “tube radio receiver” that I started with a few years ago is also waiting to be tinkered with.
Of course, the topic of retro computers does not let me go either. Here are a few devices left to restore and wait to be brought back to life. (This is where I remember right away: I’m looking for a RUN / STOP button for a Commodore Plus 4 – I would be happy if any reader could help …)
looking for a RUN / STOP key
The project with the MOS8501 CPU as a lattice – FPGA – mini board is also in the “carry on queue”. There is still a lot to do here (the level shifters are not doing as they should, the VHDL code still needs to be adapted, the prototypes Circuit boards have to be combined on one board and then also miniaturized …) So there is still enough to do.
Then there are also old devices that I would like to present here in the blog and a number of repairs that keep falling into my hands … Also one or the other HomeMatic tinkering is still pending.
I also toyed with the idea of publishing content from the blog in the form of videos on YouTube. On the one hand, however, I cannot assess whether someone is interested and whether I would like to do that to myself, to present my face in front of the camera. It would probably make more sense to do it with a more didactically gifted person as the protagonist. And of course for Lau, as fun. On the other hand, there are quite a few Youtubers here who are very experienced here (e.g. Dave Jones with his EEVblog, NoelsRetroLab, Adrian’s Digital Basement, GreatScott, ZeroBrain, JanBeta, etc.) and have been doing this for a long time. Also not to be neglected is the immense effort involved in producing such films. When I look at my assembly videos here: It takes almost one day to record the raw material when soldering the respective kit and, in total, almost three days for the cut and post-processing. Let’s see if something can come of it one day …
After the great success of my first book on the retro blog, I have now made my way through and written a second book – NO FUN – there was no success at all. I wrote the book back then in order to have a printed work of my (in) deeds on this website for myself. Because, firstly, it is much more practical to be able to quickly check something – without always having an Internet available and secondly: what if the server (s) can no longer be reached, or is deleted, or even burns down? Or worse, if someone wipes the internet…
At the time I thought to put it on with a “print on demand” option, but who knows if anyone will be interested and if I can even do it that easily. And who would spend so much money on it. Because the individual prints are also quite expensive. So the printed copies presented here are virtually unique. And I’m a little proud of it, because there’s a lot of work to be done.
So now there is the retro book no. 2 with the continuation of the blog entries from the end of the first version to the entry “Schuko socket with USB (repair)” from December 19, 2020 and that is again 96 “stories” which this time cover 498 pages. I chose “epubli” again for this print and ordered it there. This has the advantage that if I want to have one of the existing books printed, I just have to click on “order” again, since all the production data is already there.
I also learned a lot about the formatting of texts, fonts, step sizes and directories. The images are now printed at a higher resolution and all in all it looks better.
So I’ll stay tuned and in a few years, when enough content has been written again, I’ll be working on an issue again.
The Radiometer – also called lightmill – is an instructive, physical demonstration object that was invented about 100 years ago by the English physicist Crookes. This small physical-technical arrangement clearly shows how light is converted into mechanical energy.
The working princip of the solar radiometer:
Impeller inside the part evacuated glass ball
If warm light, ie sunlight, light of light bulbs or spotlights, meets with light in the spectrum of which the infrared component is present (but not cold light from fluorescent lamps) on the wing cross resting on a needle, this will turn depending on the intensity of the light source , In a particular method, a partial vacuum is generated in the glass ball, so that the air resistance is not stronger than the rotational force of the impeller generated by the light energy. The blackened surfaces of the wing cross absorb more light energy than the bright surfaces. Due to the warming of the air molecules, a much higher pressure is created on the dark areas than on the bright areas. This causes the constant rotation of the wing cross. (Brownian Molecular Theory). Depending on the light intensity, up to 3000 revolutions per minute should be achieved. (Source: Manufacturer of the Radiometer)
Again and again it happens to me that a USB memory stick loses its function and is suddenly no longer recognized. Often the stick is still registered as a drive in the system, but it lacks the disk, or even the system reports that the stick is not formatted. And even though he just recently, full of important data, has worked in another computer. (Here would now be the story with the backups or backup copies …). All these problems are mostly due to operator errors or mechanical problems. For example, an operator error may be that the stick is being pulled while one more writing is in progress. The stick is then de-energized during a process. And depending on whether the controller or flash memory can handle it, the stick will survive or not. Often, mechanical defects are the cause of breakdowns. So it may be that the solder joints between the connector and the board break, or get the connecting pins of the quartz or oscillators contact problems.
In this case, I got a miniature stick from extrememory, which does not want to give away its stored data. It is displayed in the system administration, but if you want to access it, the message “no data carrier found” comes. The attempt to format or partition over diskpart from the commandline did not work. Also various tools like “SDFormatter” or “USBstick_Formattool” failed. Even with Linux or on MAC systems, no success was achieved. So a stick for the barrel … But I thought, even if the stick in its small design rather not close to a mechanical defect – why not take a look anyway And at 16GB I will not give up so fast.
So I tried to gently open the case by first removing the metal case of the USB connector.
That works quite well. After I wanted to take a closer look at the appearing small printed circuit board with its tracks, there suddenly appeared something familiar.
That looks like an SD card. More specifically, like a microSD card.
That’s the way it was. The USB stick is nothing more than a MicroSD card reader, in which such a card is installed. Using tweezers, the SD card could be levered out.
Apparently here again the problem is with the contacts, or contact springs between card and card reader. It is the cause of the problem, because the SD card worked fine in another card reader and all the data was available. It pays to invest in front of the garbage bin for a few minutes and to inspect the innards of the device.
Some time has passed since the last blog entry. On the one hand, I put this down to a lot of work, both professionally and privately, so that a bit of the energy for blogging was missing. The last days is the beautiful weather to blame. I preferred to spend my time riding a motorcycle instead of sitting behind the PC … But I also got a little gimmick again.
FritzRoy storm glass
A colleague told me about it and at a large Internet mail-order company, I quickly found it. It is a so-called “FritzRoy storm glass“.
A storm glass is known for a long time from the seafaring. There it was used to predict weather changes. The storm glass is a glass cylinder filled with two liquids and hermetically sealed. The fluids are usually camphor and alcohol in saturated form, which do not mix but form small crystals. The formation of these crystals is related to the weather change. For a long time it was believed that the crystals react to changes in air pressure. Recent research allegedly suggests that the crystals react to electromagnetic fields called sferics. These sferics are preferably formed in low pressure areas. Thus, the storm glass shows the approach of a low pressure area and thus the bad weather.
Crystals as weather forecast
The table (from the CarloMilano user manual) shows the different crystal weather relationships.
Most of the time of the whole job is cleaning.
