Hi, I just bought one of these PWM DC motor speed controllers, powered it using a 24(V) 10(A) power supply and attached a high rpm DC motor to it for a few seconds, increased and decreased the speed with the potentiometer and everything worked fine the first time. The second time I did the same setup, however, now it looks like the speed control module always outputs the same voltage available to it, regardless of the potentiometer's position.
Nothing smells or looks burnt or anything, and I also desoldered and tested the potentiometer, and it worked fine. I used a multimeter and found out that the DC motor actually draws much more than 10amps - which I thought it wouldn't since the PSU's highest current was advertised to be 10amps. I don't know how it's possible though - and possibly that high current draw damaged a component. I'm a neophyte here and I need help identifying the problem, just hoping to be able to change the faulty component.
Thank you very much.
this is the best datasheet I could find for the DC motor (ERS-550SM 7520): http://www.evermotor.com/link/ERS-550SM.html
Although I wasn't lucky with the PWM module and didn't find anything whatsoever.
As dear @Bruce Abbott suggested, I checked the resistance between the pins of all three FETs (those with heatsinks!), and the one with the larger heatsink has almost NO resistance between any two pins. So I guess that's the problem, isn't it?