I bought an MD10-POT to control power going to an electrolyzer. My input power measures as 28 vdc and 9 amps. I verified my connections and turned on my power supply. At first everything seemed to work correctly: Moving the knob counter clockwise reduced current smoothly and had a nice feel. I had reduced the amps from 9 to 4.2 right away. I was going to take a reading with my oscilloscope. Then, after only about 20 seconds -- maybe less -- oil steam jetted out of the base of the large cap. I shut the power off the second I saw the cap blow and evacuated the area.
What happened? Should I not have expected this board to work on a resistive load?