Hi i'm having the same issue but i might be able to provide some insights nevertheless. I picked one such radial blower up at the scrapyard recently and want to use it for a climate control,fume and dust extraction system for my room. Digging through various Datasheets and reverse engineering parts of the circuitry i think this is how it goes: the mains voltage input just gets mains voltage. protective earth is the center conductor, live and neutral can be swapped without any issues. from there i just got a coarse overview of what's going on on this board and began reverse engineering the parts of it that i'm interested in. you can test for function by bridging a 10.5 Mohm resistor between PE and the pin 5 of the buttommost, first SSOP-8 package on the right side of the PCB. it should spin up quite slowly. you might need to give the blade a small knudge to get it going. if that doesn't work, your controller is likely to be broken. This is not a good test i know but it sorta works. my controller did that for a while just fine until a had a lil oopsie and had a piece of metal scrap fall from a shelf on the exposed PCB shorting a 140V AC rail to PE. after that happened and i replaced the fusible power resistor on the input after identifying it has failed, this test never worked again. it randomly spun up once when trying to measure the voltage on parts of the H-bridge but i can't reproduce it at all. from various datasheets and my reverse engineering efforts i would conclude that the control input probably requires 12-36V PWM. using a simple 555 sawtooth oscillator, operational amplifier and transistor level shifter i was able to provide the connector with a suitable PWM signal but nothing happened. the controller input is fully optoisolated. the center pin appears to be a HALL effect sensor. the left and right pins are anode and cathode of the PWM input respectively. Still be careful with what i say because i have not gotten mine running properly.