Problem diagnosis.

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So Yesterday 22 March 2026, I got a broken vacuum cleaner from a family member who asked me if i could repair it. The initial problem was that the cable was snapped off and disconnected on the inside, causing it to obviously not work. Before that i also managed to repair an electronic piano i also got from him, but i did not really document that but that was a few weeks back and the piano had the problem that a few keys where not working. I ended up fixing that and got some money for the repair. Below is an image he sent me:

Repair

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So i ended up tearig it down. I did not make a ton of photos off the teardown process but thats also not that interesting to look at. The insides are more interesting.

As you can see the wire snapped off right at the wire reel. So this is quite a mechanical construction. The white smaller circle holds a long piece of metal thats used as a spring. This spring makes it so it automatically retracts the cable when you click the retract button on the vacuum cleaner.

SO now i know what the issue is. I decided to snip the wire, then solder it together and finally cover it with heatshrink tubing to isolate the wires, as there wil be the full 230v mains voltage runing through it. This solder connection will probably be the weak point and the point of most resistance and thus might heat up a bit but i did not really experience any major overheating issues so lets hope it stays this way, but i will keep on testing. The client will take it back in about a week so enough time for testing i think. I covered those connections with a bigger heatshrink tube just to make it neater and safer.

So then i grabbed a multimeter and checked continuity and yes it works again! Then i wound up the spring and could let the reel retract the wire on its own again and its good like new!

I also did take it apart fully to clean it out and just because i was curious how everything worked and was put together. So below are some teardown pics.

teardown pics

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Control panel:

The board itself:

As you can se the board has 3 chips on it. The 8 pin one in the middle is a Microchip 24xxxx series eeprom chip that stores the settings (It has a function that it remembers what setting it was on, last poweroff). The one next to it is a renesas pd78f9212cs 8-Bit microcontroller which is the brains off the operation and controls everthing. Yes even a vacuum cleaner has firmware and a computer inside. Kind of ridiculous isn’t it :) ?! The last one is a multiplexer that drives the leds. I dont see a TRIAC on the board so it must be integrated into the motor cause i dont see how such a tiny mcu can drive a motor that works at mains voltage and draws a ton of current. Normally the TRIAC is integrated onto the board on a heatsink. That triac component i am talking about, can be compared to an electronic switch. Its similar to a mosfet/transistor, but it can switch Mains AC voltage while a transistor or mosfet primarily switches DC voltage. It basically chops up the AC sinewave and that makes it so the output receives more or less power. Same component is used in a dimmer for lets say a lightbulb.

Motor:

And indeed the motor has 3 wires. Normally its a dumb motor that has 2 wires going to it. Simply live and neutral off the mains voltage. In our case it has an extra control wire which kind of proves my guess that the Triac is integrated into the motor

Conclusion

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So it was not that difficult to repair. Putting it back together and taking it apart was a bit more difficult. There where some screws hidden under the filter and one off the buttons, but other than that i could open it in a small matter off time. Its always interesting to look inside devices and it also gives me a reason to take them apart without making people upset :). This repair took arround 3,5 hours and my client wants to give me 35 euro for it which is nice. I kind of hope i can keep up this hobby repairs so i can earn some money as i am a bit broke and dont really have found a job (that i like). Many thanks to my family and friends who sometimes bring me devices, either to try and repair or for me to take apart. I am not an expert into repairs, but so far i managed to repair quite a bit off stuff for family already and i am pretty much one off the few technical ones in the family. I do watch repair channels like ‘My mate vince’, ‘Buy it fix it’ and a few others who do repairs. I not only learn from those creators but also can sometimes give advise and do react to them sometimes. I kind of hope we get laws that enforce companies to make products somewhat repairable, but i heard that there is a law incomming for that so i hope it gets through. This product did not have any glue or proprietary screws, but i do think it does have some proprietary parts like the microcontroller’s software which i dont think you can easily get. I am not fully sure though. I did see that miele does sell a replacement motor for the device which is nice. And its far more repairable than lets say, Apple products.