Vacuum cleaner repair

[Its wednesday my dudes]

Hi guys

Yesterday I discovered that my vacuum cleaner suddenly stopped working. But before throwing it out and replacing it with a new one I want to give it a repair attempt. Since I am dealing with mains voltage here and my usual projects is simple low voltage hobbyist stuff I wanted to get some input first.

Basically the vacuum cleaner gives no sign of life when turning it on. Cables are good. I opened it up and this is the board. So far I googled, that it consists a triac (package code something like BTB12 6008 DT (?), couldn't find the exact match). The other IC (package code CR8F6 1D12 (), didn't find anything about it) might be a microcontroller. The board has a NTC thermistor connected to it. So would your plan of attack be? I was thinking about unsoldering the triac and testing it if it works according to this manual. https://instrumentationtools.com/test-triac-multimeter/

I was also thinking about a quick and dirty fix by bridging the triac contacts so that the motor just runs on full power all the time. Not sure if this is a good idea though, since there is a NTC present.

I've attached some pictures of the board.

Thanks!

[perieanuo]

verify voltage on big electrolytic cap, with care, you have 220V on that pcb, maybe the blue thing is the fuse is it ok?
maybe you got lucky and some condensator is dead, like the yellow one who i guess make the small voltage for the IC with the rectifier diode next to him (D1?)
verify the zener also, maybe it's dead
the board should be easy to fix unless the IC is dead

[amyk]

How "smart" is this vacuum to need a microcontroller...?

You can test the motor by bypassing the triac. I assume this is not a cordless one and the motor is a universal brushed motor.

The MCU looks like it's powered by a capacitive dropper so check the capacitance of C1 - they tend to fail by decreasing in capacitance over time.

If you don't need the "smart" extra features you can always get a suitably rated switch and turn it into a regular dumb vacuum.

[wraper]

First check if motor has continuity to begin with. It may be just worn off brushes.

[EHT]

It looks similar to this Miele I fixed.

How "smart" is this vacuum to need a microcontroller...?

Oh yes! I was surprised by this too - same in the Miele!

The MCU looks like it's powered by a capacitive dropper so check the capacitance of C1 - they tend to fail by decreasing in capacitance over time.

Yes, that is what failed in mine. Measure DCV and ACV on the microcontroller's power lines. The thing which was most fiddle was finding a replacement that would physically match.

Also you can test the triac by using a bench PSU to apply a few volts to the gate and a small load like an LED. Test it in both directions. This was easy on the Miele because the triac was mounted externally.

[wraper]

I doubt that this is microcontroller. More like analog phase shift control IC for power regulation and overheat protection.

[amyk]

I doubt that this is microcontroller. More like analog phase shift control IC for power regulation and overheat protection.

I suspect it is one of the "CR8F" family, possibly CR8F6122: https://datasheetspdf.com/pdf-file/1054727/STMicroelectronics/CR8F6122/1

...of which there is disturbingly little information out there, just these datasheets, and zero mention of that product or even the "CR8F core" on ST's own website.

[wraper]

I suspect it is one of the "CR8F" family, possibly CR8F6122

Pinout seems to match.

[Its wednesday my dudes]

Hi guys,

Thanks for your help. I worked through the list of your suggestions and turns out that the big capacitor was dead. Swapped out the capacitor, now the cleaner works flawlessly again. Thanks alot!

[Raj54]

Please be careful when checking the voltage on the large electrolytic capacitor. The PCB may have 220V, so exercise caution. The blue component may be the fuse - please check if it's okay. It's possible that a capacitor, such as the yellow one that provides low voltage to the IC with the rectifier diode (D1), is dead. Please also check the zener - it may be dead as well. Fixing the board should be easy unless the IC is dead.

[cruff]

The original poster reported that it was repaired more than two years ago.