That PCB? It's a variable speed motor control. Sure you can replace it, but the replacement is far more complex than a potentiometer due to the power levels involved. The replacement is going to work similarly to the PCB already in there except it won't be designed to fit in the case. The quickest/dirtiest thing you can try is an AC lightbulb dimmer between the mains and the motor, it will probably give you coarse speed control. You might also blow up the dimmer if it's poorly designed (they don't expect inductive loads).
Originally Posted by Greg Davis
Computer fans are 12V BLDC motors, this thing is an AC squirrel-cage motor. They have totally different supply and control requirements.
See the two surface-mount black things above and below the capacitor that's overheating? My guess is that the top one (3 pins) is a triac which is doing phase control on the motor. Replacing that on the stirrer that doesn't work at all might get you somewhere, or it might not.
Last edited by polyglot; 07-16-2013 at 07:25 PM. Click to view previous post history.