I've been given a fairly tidy Makita 440, a 1kW 230V vacuum cleaner which can be triggered by another power tool plugged into it. It's dead with no reaction when switched on.
I've stripped it down and removed the motor which appears OK, spins with just the resistance one would expect from 4 brushes and doesn't smell of burnt rein/lacquer. The motor is controlled by a PCB with what looks like a triac in the middle and probing with a voltmeter only gives 82V ac at the motor output. The board is a Selmo 4707 but a web search only finds the italian manufacturer. When switched on and the motor disconnected four 2.7kOhm dropper resistors in series get hot to touch so I guess something has shorted, probably the triac but only the middle two resistors seem discolured.
No problem I thought, do without the ancillary sockets and control board but I see this model is available in 110V as well as 230V so the only difference will be in this board rather than the motor. No identification on the motor and I wonder what to feed it, I have a PWM voltage kit from Velleman which should do the job.
Of course the motor may be goosed and the high current draw killed the board but it does have a resistance of 8 Ohms static which seems reasonable and would give a start up draw of 11 Amps if it is designed for 81V working.
I'm wondering at what to do next? The skip is an option.
AJH