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miscellaneous and news, repair and restauration

Repairing a TRADFRI smart plug – When the relay goes haywire

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A quick note: Parts of the wording in this post were drafted with the help of AI. … (clearly recognizable in the style:

A repair story from the world of smart Swedish furniture.

The symptom: click-click-click…

As so often happens, it started with an annoying noise. My TRADFRI socket from the big Swedish furniture store had suddenly decided to put on a percussion performance. Click-click-click-click—the switching relay kept turning on and off as if it were having an epileptic seizure. The connected lamp flickered like in a horror movie, and I knew: I had to do something about this again.

The diagnosis: An old acquaintance

Anyone who has been repairing electronics for a long time is familiar with the problem: electrolytic capacitors are the Achilles heel of many devices. They dry out, lose capacity, and suddenly nothing works anymore. I have created a video of the symptoms of this problem:

The culprit: a 680µF/10V electrolytic capacitor in the power supply of the socket. When it stops working, the power supply becomes unstable and the control circuit panics. The relay switches back and forth uncontrollably—click, click, click.

Figure 1: Close-up of the defective electrolytic capacitor on the circuit board

The battle with the case: Deluxe gluing extravaganza

Now comes the part that turns a simple repair into a test of patience. IKEA apparently thought, “Anyone who wants to repair this TRADFRI socket should have to work for it!” The housing is not only secured with screws, but also glued. And really glued.

Step 1: The visible screws

First, the good news: there are indeed screws. After removing them, you briefly think, “Aha, I’ve got it!”—but no such luck.

Figure 2: Back side open with screws visible

Step 2: The invisible adhesive trap

The housing is rock solid. There is a continuous adhesive seam between the two halves of the housing that cannot be removed with bare hands. Here is my tool recommendation:

  • Several plastic spudgers or old EC cards
  • or a cable knife (if there is no other option)
  • A lot of patience
  • Even more patience

The technique: Heat the case all around (NOT too hot, otherwise the plastic tabs will melt!), then carefully insert the spudger between the two halves of the case. Work your way forward millimeter by millimeter. The whole thing will creak, groan, and squeak—but eventually the adhesive or plastic will give way.

Figure 3: Housing is open

Step 3: Don’t forget the clips

In addition to the adhesive, there are hidden locking tabs on the sides. These must be released at the same time while prying open the case. A third arm would be helpful here. However, a vise with soft jaws will also do the trick.

After about 15 minutes of patient work (and a few creative curses), the case finally comes apart. Fortunately, the breakage is manageable—with this type of bonding, the case is often just scrap metal afterwards.

The repair: Replace the capacitor

Now it’s easy. The defective electrolytic capacitor is quickly identified:

Required materials:

  • 1x electrolytic capacitor 680µF / 10V (105°C types recommended)
  • Soldering iron (20-60W)
  • Desoldering braid or desoldering pump
  • solder

The exchange:

  1. Desoldering the old capacitor: Heat the solder joints from the underside using the desoldering braid and remove the tin. Caution: The circuit board is double-sided, so remove the tin from both sides!
  2. Insert new capacitor: Pay attention to polarity! The negative pole is marked on the capacitor (usually a white stripe with a minus sign). On the circuit board, a plus sign is usually marked on the corresponding pad.
  3. Soldering: Insert the legs, solder from below, and cut off any excess wire.
Figure 4: New capacitor soldered onto the circuit board

The functional test

Carefully place the circuit board back into the housing (do not seal it yet!), plug it in, and… silence. Wonderful silence. No more clicking. The LED lights up steadily, the relay switches cleanly, and the outlet works perfectly again.

Das Gehäuse wieder schließen

Now comes the crucial question: How do I close this thing again?

The old adhesive is worn out. My solution: two-component epoxy resin. Apply a thin layer to the areas to be bonded, press the housing halves together, secure with adhesive tape, and leave to harden overnight. Alternatively: use small screws at strategic points (where there are no electronic components in the way).

Conclusion: Is it worth repairing?

Pro:

  • The socket is working again.
  • Cost: ~2 euros for the capacitor
  • Satisfying feeling of repair
  • One less device in the trash

Contra:

  • Time required: approx.  0.5 hours
  • Opening the housing is destructive
  • New TRADFRI socket costs only approx. 10-15 euros
  • The warranty is gone, of course.

For me personally, it was worth it. Not because of the cost savings, but on principle. This throwaway mentality is just annoying. A simple capacitor for €2 gets the device working again—I can’t just throw away the whole thing!

Tips for imitators

  1. Safety first: Before opening, unplug the device and wait 5 minutes!
  2. Document: Take photos at every step. Helps with assembly.
  3. Have spare parts ready: Order the capacitor before you open up.
  4. Housing replacement: Ask IKEA if replacement housings are available (spoiler: probably not ).

closing remarks

The TRADFRI socket is an affordable smart home device with a rather stupid design decision: the glued housing. If it were just screwed on, anyone could carry out this simple repair. This turns a 5-minute repair into half an hour of fiddling around.

But: It is doable. And it works. My TRADFRI socket has been running for weeks without any problems. The clicking is history.

With that in mind: repair your devices, folks! It’s worth it.

Have you ever repaired TRADFRI devices? Share your experiences in the comments!

Disclaimer: This repair is carried out at your own risk. Working with mains voltage poses a risk to life. If in doubt: keep your hands off and consult a specialist!

miscellaneous and news, repair and restauration

When the brush stops turning – or: Repairing the Kärcher FC7

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“Freshly mopped floors without having to vacuum beforehand: The FC 7 Cordless hard floor cleaner removes all types of dry and damp everyday dirt in one step.” (Original text kaercher.com)

You get this product promise on the manufacturer’s website if you are interested in the FC7 electric hard floor cleaner. However, when this promise is no longer kept, I find out about the existence of these appliances. Because then I am asked to check why something is no longer working as it should. This is also the case here. The brushes (rollers – whatever these parts are called) no longer rotate, according to the problem description. Or to be more precise, they only turn sometimes when the bottom part of the moving handle is in a certain position. And since the handle (in which all the electronics such as batteries, BMS and operating elements are housed) can be moved within a wide range, it is reasonable to assume that there is a cable break or similar contact problem.

This is not exactly a complex problem, but perhaps one or the other is interested in how the problem can be solved with more or less effort.

The first step is to remove the wastewater tank and the four cleaning rollers. The screws on the drive cover and battery cover can then be loosened and the covers removed.

Screws of the drive cover
Battery/electronics cover screws

Once the covers have been loosened, they can be removed. The circuit board with the BMS and the control electronics of the device can be seen under the battery cover. The 18650 Li-Ion cells are located underneath. The outlets to the bottom drive, to the control unit in the handle, etc. are plugged in.

Circuit board with BMS and control unit

The eight-pin plug at the bottom left of the picture must be disconnected. It connects the brush drive to the electronics. Six of the eight pins of the plug are occupied. One red and one black wire are used to supply the DC motor (yes, only a DC brush motor has been installed here and not a brushless one …) and two brown wires are laid to the pins that form the resistance sensor for the water level in the dirty water tank. Two blue wires control the solenoid valve of the water inlet.

As the fault is in the motor drive (depending on the position of the handle, the motor may or may not turn), the fault may be in the cable connection from the circuit board to the motor. The fault was quickly discovered with the continuity test of the multimeter. The black cable to the motor was broken.

Broken cable (black wire to DC motor)

The breaking point is exactly in the area where the handle is movably attached to the floor unit. This is exactly where the wiring harness and the rubber hose for the water guide are inserted. Constantly moving the cable harness will inevitably damage and break the cables in the long term. Especially if the handle is used at very shallow angles, for example to clean the floor under boxes, chests of drawers, etc.

Wire soldered and insulated with heat-shrink tubing

I did the repair here by soldering the wire together and protecting it with heat-shrink tubing. I wrapped the damaged cable protection conduit with insulating tape. This should hold for some time. As the part will not last forever due to its design, the wiring harness should be completely replaced during the next repair. (as this is probably not available as a spare part, you will probably have to make one yourself – but then with more stable, highly flexible wires…)

The components could now be reassembled. Place the rollers in the green/blue colors on the drive hubs and screw everything back together.

Broken cable connections and torn toothed belts in the motor unit are obviously the most common faults with this appliance.

 

repair and restauration, vintage toys

“Tricky Traps” restoration

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In this post, I’m going to take a look at the restoration – or rather repair – of a handheld game that I recently received for review. It has the name “Tricky Traps”. This means something like “tricky or tricky traps”

The game “Tricky Traps” by Tomy is a mechanical game of skill that was originally released in the 1970s. It consists of a maze-like playing field in which the player must navigate a small metal ball through a series of obstacles and traps. The aim of the game is to successfully maneuver the ball through the maze to the finish without it falling into one of the many traps. There are five balls available. The game is timed.

Tricky Traps

Game mechanics:

  • The player starts the game with a rotary knob, which sets a small electric motor in motion. This motor drives the “traps” and also the rotary knob itself via a gearbox. This is how the “timer” is realized. Once the rotary knob has completed about three quarters of a turn, the motor stops again and the game is over. This is solved by a contact spring, which is pressed down onto a mating contact by a small bar at the bottom of the rotary knob.
  • Once the game has started, the red button can be used to release a ball into the track. The white button at the bottom is the actual and only game button. It lifts the ball with a small cylinder so that it can move through the various parts of the playing field. You have to do this with the right timing.
  • There are numerous obstacles on the playing field, such as rotating disks, small ramps, narrow passages and a rotating magnet that can stop the ball or cause it to fall into a trap.

The colorful design is typical of the mechanical games of the 70s and 80s. It is made of plastic and the moving parts are usually brightly colored.

The technical problems that occur often in such old games are:

  • leaking batteries, which usually cause corrosion and destruction of the contacts
  • Brittle plastic, which mainly occurs with gearwheels that are mounted on brass shafts and therefore start to slip. This also means that housing gears often no longer hold together properly.
  • Electric motors whose brushes are worn so that they no longer turn
  • Resinous grease and oils that make moving parts sluggish
  • Wires and electrical connections that are corroded and broken

All of these points can be found very often during restoration and must be fixed. This can also be done more or less easily. After carefully opening and inspecting the appliance, I actually start by completely dismantling and cleaning the parts. Then I try to repair any broken plastic parts. Here I use various adhesives as far as possible. Sometimes it is also necessary to reproduce a part with a 3D printer. Of course, this assumes that enough of the original part is still available to reconstruct it accurately. The electrical components of these devices are the easiest to repair, as there are usually no electronics with any components with ICs that are no longer manufactured.

Revealing the parts after disassembly

Gearbox
Assembly after cleaning

 

“Ball” button to start the ball
repair and restauration

Keysight DSO-X 2012A oscilloscope dies in standby – power supply replacement

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In an old post from 2019 I reported about oscilloscopes from the manufacturer Keysight and their problem with a sudden failure. (see link). At that time, it was about oscilloscopes suddenly refusing to work – sometimes with a bang and subsequent smell of “power”. Or simply nothing happened at all after switching on. The reason was and is always the failure of the installed 12VDC power supply CCH0123F1-Z03A. The oscilloscope is designed in such a way that the power supply is still connected to the mains when the “main switch” of the oscilloscope is switched off and is operated in standby mode. The push button switch located on the front panel of the unit then switches the power supply into PowerON mode and 12V power on.

If the devices in the laboratories are permanently connected to live sockets, it is not surprising that the devices age faster than the good old boxes with the cathode ray tubes. The parts, which fall victim to the permanent power supply by thermal continuous load, I have, as well as also the repair expenditure in the contribution at that time represented. On the part of the distributing companies also a reordering or a replacement delivery of new power supplies is not intended or desired. If the devices fail within the warranty period, the replacement by the manufacturer is no problem. If the devices fail after a few years in the laboratory or workshop (it doesn’t matter if they are in use every day, or just stand around plugged in and switched off), then a normal repair service process is carried out by the manufacturer. There are then also the proper tariffs for the service of measurement technology to pay.

In the picture above: “new Meanwell Powersupply” below: “original Lineage Power”.

The power supplies are quite easy to repair, as described in the old report. However, the repair is also quite time-consuming. Of course, it is faster to install a new power supply. Unfortunately, the distributors of the Keysight oscilloscopes do not offer spare parts support and I could not find a direct supplier of the original Lineage power supply. But there is another alternative: In the forum of the EEV blog some users have found alternative power supplies that fit into the DSO-X oscilloscopes. A suitable model is the RPSG-160-12 from Meanwell. It is a 12V 160W power supply. The designation “G” in RPSG indicates that there is also a 5V standby supply. And it is exactly this function that the DSO-X needs. Because as described before, the front switch on the osci is not intended to disconnect the primary side of the mains supply, but only to switch a line on the DC low voltage connector to ground. This line controls the “PowerON pin” in the power supply.

Mechanically, the Meanwell almost fits on the mounting brackets of the DSO-X. “Almost” means that the distance between the mounting holes of the long side on the powersupply is about one millimeter further apart than the mounting bolts on the chassis of the oscilloscope. However, this can be quickly adjusted with a small round file or a 4mm drill bit. Now the Meanwell Powersupply can be attached to the oscilloscope chassis with the original Torx screws. The plug connection for the AC supply from the OSZI board to the power supply can be taken directly from the old power supply.

Pinout of the Meanwell connector strips

The 12V voltage supply at CN2 of the power supply is connected to pins 1,2,3,4 (+12V) and 5,6,7,8 (GND). The connection line to the oscillator must be adapted accordingly.

DC12V outputs on CN2

The picture below shows the pins of the connector strip on the oscilloscope labeled.

DC12V input to oscilloscope

I re-pinned the wires to fit and connected the connector to the powersupply as shown below.

The main power supply to the oscilloscope is now established. Only the “power-on line” (PowerOn) is missing. For this I disconnected the 7th pin (GND) and the 9th pin (Switch) from the old connector and soldered them directly to the standby board of the power supply. The wire at the lowest pin of the standby board is the signal “PowerOn” and the one above is GND. So the power supply can be powered up with the front power switch on the oscilloscope.

“Control lines” for the PowerOn of the power supply unit

 

General view of the wiring

After a short function test and checking of the voltage (can be corrected if necessary also at the trim potentiometer at the power supply) the rebuilding is finished and the assembly can take place again.

repair and restauration

Neumann KH-120 mystery noise fix

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This time, a defective pair of active speakers found me, which comes from the professional corner of sound generating devices. These devices also occasionally have problems or fail. If you do a little research in the forums on the Internet, the KH-120 boxes are very robust and durable. The only issues I’ve read about are power supply failures. Occasionally there are also reports of a clear noise or whistling even if no signal is applied.

Exactly this problem was shown by these devices. After switching on, there was a hissing noise up to slight whistling tones. These could be influenced with the filter and gain switches, but not remedied. If the loudspeakers were in use for a long time – after about half an hour, then the noise decreased.
Unfortunately I didn’t manage to find useful information about these errors on the net, let alone a circuit diagram of the board. So there is nothing left but to search for it yourself, analyze the board and search systematically for the error.
Starting with the removal of the four long Allen screws, the two halves of the housing can be carefully pulled apart. This then reveals two white blocks of insulation. These can easily be removed. The wire connection to the loudspeakers can be detached from the circuit board using a four-pole plug. Likewise the connection to the small LED logo board.

KH-120 is open and the insulation material removed
The picture shows the connector with the wires to the speakers

Next, the circuit board can be unscrewed from the housing. (a Torx bit is to be used here) All screws except for the two black cross-head screws must be loosened. Then carefully remove the board from the housing.

Circuit board of th Neumann KH-120

The board looks very good. All components that can be set into mechanical vibrations and possibly resonance by the sound are secured with elastic adhesive. The board layout is nice and clear. You can see the mains input and the mains filter at the bottom left of the picture. Above it is the large electrolytic capacitor for smoothing the direct voltage generated from the mains voltage.

The power supply is a switching power supply. The Mosfet controlled by a controller chip clocks the transformer. On the secondary side it is rectified again and the symmetrical voltages +Ub and -Ub for the power section of the output stages, as well as +15V and -15V for the supply of the pre-amplification and signal processing are generated. Ub is at -42 or + 42V. The power output stages are two TDA7293 ICs. One controls the tweeter and the other controls the woofer.

backside of the circuit board

In order to look for the cause of the problem, one proceeds systematically. I first checked the supply voltages with a multimeter. Of course they are there. But you only see the truth when you look at it a little more closely. The multimeter is no longer sufficient here. An oscilloscope also reveals the AC component or residual ripple.

The picture shows the AC part of the -15V power supply. At around 800mV, however, it is suspiciously high. The period duration of these peaks with 30µs indicates that the transformer is regulated when the power supply unit hardly has to deliver any power. The switching frequency of the transformer can be seen within the pulses. But what could still be seen and cannot be seen in the still image are lower-frequency, asymmetrical components with an equally high amplitude. Accordingly, there appears to be a problem with smoothing the stress. So I examined the structure of the -15V supply. And look, the +/- 15V are implemented with a series regulator. A 7815 controller is used for the + 15V and a 7915 controller in the TO220 housing for the -15V. In the Note application, capacitors to ground are specified for the IC at the input and output. And that’s exactly what I took a closer look at first. An electrolytic capacitor with 100µF / 35V and 105 ° is used at the input of the 7915. This capacitor had to go out to measure. Immediately after the removal, it seemed to me that the weight of the component was too light – it didn’t feel like anything. So get to the LCR bridge and lo and behold, the capacity was somewhere around 1.4µF.

the polluter

A new electrolytic capacitor was installed quickly and the renewed measurement of the voltages revealed a nice signal again. The AC share was now much lower and the irregular disturbances had disappeared. Only the switching of the transformer could still be seen. What was still noticeable, or no longer noticeable, were the noises from the loudspeakers – the noise was gone.

the cause was built in here

 

 

repair and restauration

Sony Walkman WM-DD11

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The portable cassette player from the manufacturer SONY with the type designation WM-DD11 is the content of this article. Colloquially known as “Walkman”, I received this part for my collection. Of course with the comment “defective” – ​​so again a little challenge and at the same time the hope that no mechanical, no longer available parts are affected. My request before the purchase whether there was any damage to the circuit board was also answered in the negative. The device is so far in order, the tape of an inserted cassette is moving – there is just no sound from the headphones. So ideal conditions for a restoration.

But unfortunately you cannot trust every statement and you cannot look “under the hood” beforehand and convince yourself whether the actual condition of a device corresponds to the description. When I held the part in my hands, the first impression was also very convincing. There were no noticeable scratches and dents. The area of ​​the battery compartment that was visible from the outside was also clean. So batteries inserted, also an audio cassette and then pressed on play. Lo and behold, the tape transport runs as described. Even as described, the part does not make any sound. So perfect starting conditions for my mini repair / restoration project.

But before I start dismantling, I did a little research on the history of SONY’s DD Walkman series. The first model in the DD series was sold in 1982. The designation “DD” stands for “Disc Drive”, which means that the “Disk”, i.e. the flywheel disk, is also part of the capstan drive system (motor). The belt for the other drives (tape reels) is placed directly around the disk. There are / were two price brackets of the DD models – the DD series with one-digit numbering (DD-1, DD-2, etc.) and those with two-digit numbering (DD-11, …). The devices with the single-digit number belong to the “high-end rail”. The device restored here comes from the “cheap line”. The DD-11 is not so high-quality and is also more simply constructed, but defective devices are available for very little money and are also fairly easy to repair. (The DD-11, for example, does not have a center wheel, an often defective part of the high-end series that is broken due to weak material. What then usually remains are defects in the electronics or on the mechanical side – an aged belt The belt is the same as that already installed in the legendary TPS-L2 Walkman and has the component serial number: SN 3-499-042-99 (this source or number has not been verified) You can also find the belt if you go to “TPS -L2 belt “searches on various online portals.But now enough information on the general part. I experienced a sobering and grounding of my restoration euphoria immediately after unscrewing and opening the case. Unfortunately, the circuit board is not at all undamaged. Once again someone did not remove the 1.5Volt cells and left them in the device for a very, very long time.

The batteries that leaked, as it is, have left clear marks on the circuit board. This means that extensive cleaning of the circuit board is necessary before the search for corroded conductor tracks can begin.

After cleaning and removing the battery electrolyte residues, I was able to make out a few defective conductor tracks. Fortunately, these are pretty easy to fix. In most cases it is sufficient to remove the solder resist in the defective area and to tin the exposed copper tracks. Depending on the width of the track, the defective part of the track is then reconnected with individual strands or wires.

Now the time has come to carry out a first functional test after a provisional assembly. And as described, the capstan drive works, the tape is transported – but there is no noise whatsoever from the connected speakers. Now is the time to look at the number one source of failure – the old electrolytic capacitors. Eleven of these are installed on the board.

When I removed the first electrolytic capacitor for a capacity test, the well-known fishy smell rose again. As expected, the capacitance of the capacitor was also well below the nominal value. So I made a spontaneous decision to remove all eleven electrolytic capacitors in order to swap space. (In modern language it is called “recap”: D)

The following values ​​must be renewed:
– 5 Stück 220 µF / 4V
– 1 Stück 100µF / 4V
– 3 Stück  47µF / 4V
– 1 Stück 10µF / 16V
– 1 Stück 4.7µF / 25V

 

I like to replace the SMD electrolytic capacitors with SMD multilayer capacitors, as these are now also available in very small designs in high capacities with suitable dielectric strength.

After the renewal, the board looks nice again. A repeated provisional commissioning shows that the effort was worth it. The music on the inserted tape sounds in the expected quality. The next step is to calibrate or adjust the belt speed. A reference tape is required for this. Years ago I recorded one with a very good tape recorder. The recording consists of a 1kHz and a 5kHz sine tone. This band is now used as a reference in the DD11. To do this, the output of the DD11 is connected to a frequency counter or oscilloscope and adjusted with the trimmer potentiometer during playback until the 1000 Hz or 5000 Hz can be seen exactly on the oscilloscope.

The Walkman can now be reassembled. All screws are properly tightened again and finally the function tested again and the beautiful piece can be put in the showcase …

miscellaneous and news, repair and restauration

HomeMatic smoke detector HM-SEC-SD quick repair

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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.

miscellaneous and news, repair and restauration

Homematic actuator quick repair (dimming actuator RS485)

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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.

Installation locations of C1 and C2

 

 

 

 

 

 

repair and restauration

Wall socket with integrated USB port (repair)

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Thanks to the USB standard, it is now easy to operate or charge your mobile phones, tablets, Arduinos, Raspberry PIs, toothbrushes, power banks, etc., etc., with one and the same charging adapter or plug-in power supply. The “plug-in power supply” is an AC / DC converter which, ideally, electrically isolates the mains side with the 240VAC / 50Hz from the low-voltage direct voltage side in compliance with the applicable regulations. The low-voltage side provides the 5VDC via a USB-A socket. Depending on the model and origin, maximum currents of 1A up to approx. 2A can be taken.

Due to the large number of USB-powered devices in households, there are also quite a few of these plug-in power supplies. In order to operate the plug-in power supply, you naturally also need a socket in the house installation in order to connect the power supply to the utility grid. If several USB devices are in operation, or better – in charging mode, some of the sockets in the household are quickly occupied and the power supply for more important devices such as coffee machines and the like is missing …

Some manufacturers came up with the idea of ​​integrating a USB-compliant power supply unit with a corresponding USB socket into a Schuko socket that was designed for installation in a wall outlet, without losing the space for the Schuko socket.

These sockets with integrated USB power supplies are nothing new and have therefore been on the market for several years. Of course, I also had to install such sockets at the time, because they are really extremely practical. So – now, of course, the years have passed and the service life of the power supplies built into the sockets is coming to an end and they will fail. More precisely, they no longer provide a 5V supply.

no more voltage at the 5V output

However, since I don’t throw everything away and replace it with new ones – the sockets were also expensive at the time – my plan was to look for the fault and repair them if possible. In this case it is a Busch-Jaeger socket of the type 20EUCBUSB-214-500 which now refuses to function. The power supply unit should require approx. 100mW in standby mode and with 5VCD it can deliver a maximum current of 700mA.

After removing the socket, it was also quickly dismantled. The plastic cover attached to the rear is held in place on the opposite side by means of locking lugs. Now a circuit board came out that can be easily pulled out. The contact to the network side and also to the USB socket is realized via spring contact pins. It should be mentioned right away – they fall out quickly. That is why you should always work the socket with the back facing up. This saves you the hassle of searching for the little pens.

cover removed
Socket without power supply board

 

When the board was now released from its housing, at least one problem was revealed, which explains the failure of the power supply. A small chip on the board had a hole that definitely doesn’t belong there. The components surrounding it also showed traces of smoke. Thanks to another functioning socket of this series, I was able to identify the IC.

Power supply board
the hole in the IC doesn’t belong there
“Gunsmoke traces” on the resistance

 

It is a Link Switch-II series LNK614DG from PowerIntegrations. It is a small ALL-IN-ONE IC that has integrated the power FET, the oscillator and the control via a feedback winding of the transformer. The power rating according to the data sheet is 3.5W installed in a closed housing and 4.1W in an open frame or ventilated state.

“typical” application – Quelle: Datenblatt https://ac-dc.power.com/products/product-archive/linkswitch-ii/

The chip therefore only needs a few peripheral components, which in this case also makes it easier to search for further errors. On the network side, only the AC rectification and smoothing as well as the line filtering are necessary. These components were in top condition and worked. Then there is only the transformer with its primary, secondary and feedback winding, the secondary rectification and smoothing and a few resistors that are connected as a divider. No fault was found with any of these components. So – who dares wins – the IC ordered and exchanged – and bingo – the 5V are back at the exit and can also be loaded.

the new chip before installation 🙂

 

 

 

 

 

 

repair and restauration, vintage toys

Tomy Racing Cockpit – electrical wiring

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Due to some inquiries regarding the electrical wiring of the Tomy Racing cockpit, I sat down and drew out the wiring. There are apparently many contemporaries who still find toys from the 80s in their basements, attics, etc. and repair them again. With the Tomy Cockpit it happens again and again that the thin wires break off when they are dismantled or the soldered joints no longer hold, often forgotten cells in the battery compartment have dissolved and the contacts and soldered joints are corroded as a result.

I show a sketch of the wiring in the following figure.

By the way, I only use two 1.5V cells, since the parallel connection of two cells each in the battery compartment is nonsense, as the cells are guaranteed to have different internal resistances and thus comfortably discharge each other even when they are not used.

In order to be able to identify the components shown in the sketch in the racing cockpit, I also took photos of them.

This is the back of the “switch” that represents the cockpit’s ignition lock and with which the system is switched on.

I called this part “breaker” because it is a normally closed contact that is triggered by a small “gearwheel” and causes the drum lighting to flash. That happens when you leave the “street”.

These are the connections of the battery box. I doubt whether the colors of the wires are the same for all versions. Because in the devices that I have since revived, different wire colors were installed.

With this information it should now be a little easier to recreate the broken wires and solder joints.