Folletto vacuum cleaner are made by Vorwerk https://en.wikipedia.org/wiki/Vorwerk_(company) and sold here in italy with the brand of "Folletto" (Elf in english).
I've found a VK-140, that is a model from 2005 almost. Mine seems pretty new. I think it has been used just a couple of times. However it doesn't work. The main motor does not spin.
At first I though there was a problem with the power cord. I've opened it and checked the main voltage. The power cord, and the main switch works.
It's the first time for me to see a vacuum cleaner with an electronic board, usually there's just a simple main AC voltage brushed motor. This time there's some kind of elecontric to drive the motor.
Investigating further I've find this is a switched reluctance motor motor. IGBT transistor are used to drive the motor.
The power section has 4 G10T60 IGBT (600V 10A) and 4 D04E60 dioed (600V 6A).
The core of the controller it's a PIC18F24K20.
Between the MCU and the power section we can find an high-side / low-side gate driver, the FAN7382.
The motor spins using hands, so it's not locked. A visual inspection does not reveal any compoent burned.
I only hear a three clicky sound when trying to power the vacuum on.
Continuity on the motor seems ok, 1.4ohm almost for each winding.
First investigation goes to the Mosfet and the power diodes. I've cheked them removing the motor and checking continuity. Nothing seems shorted. I've also try with the diode testing, and all seems ok.
Then I've attached my portable DSO150 oscilloscope to the main output. It has 50Vpk as max input voltage, so using a 10x probe I can test up to 500V. I've not use my main oscilloscope cause I was going to test something that's potentially is on the earth ground, take a look at this video for further information https://www.youtube.com/watch?v=xaELqAo4kkQ. I've attached it directly on the motor input and checked the output.
Seems there's nothing on the one channel. So I've sone something I could have save, I've removed all the power section compoents (the igbt and diodes) and checked on the bench, they are all ok. Maybe I should have skipped this test.
Now I've tested the boost diode of the FAN7382, in one channel there's a short on the diode. I've removed it and checked alone, but it was not the diode. So it should be something related to the FAN7382.
I've ordered a couple of this IC. Soldered all back and voilà, it's working.
Maybe I should save myself some time checking it directly without desoldering all the power section, but most important is that I've repair it, and I've learn something.
Notes
- read risk disclaimer
- excuse my bad english