I have a corning stir plate that I picked for $3 at the local upcycle place and it runs but it randomly increases and decreases speed no matter what
setting it is on. It will increase rotation up to the desired setting and then decrease to almost nothing and then back up again ad infinitum. I have
almost no electrical experience and was gonna start by replacing the triac. ???aga - 20-12-2017 at 12:05
Most likely the control pot.
If it is a variable resistor, try pushing the knob in firmly and rotating it all the way left and right to try to clean up the carbon track.
If it's digital (with buttons to increase/decrease speed) most likely is the speed sensor, which means taking it all to bits and finding out
where/what the sensor is.Radium212 - 26-12-2017 at 03:38
Maybe a damaged transistor?NEMO-Chemistry - 26-12-2017 at 04:16
Nah aga is right, a transistor normally works or dosnt works, a variable pot normally causes the speed change, the other thing that can cause this
type of thing is bad solder joint, but to be honest thats pretty rare to show up like this.
I would change the pot, its dead easy to do. You dont normally have to be rigid on the values, also you can add resistors etc to get the desired value
if you got already got a spare one.
