Ok, so quick sitrep.
I installed a heatbed, power expander and external powersupply.
I’ve printed over 24h with this setup, then when I wanted to start another print (heating extruder, bed and turning on the fan) the power expander started to produce smoke…
I’ve attached some pictures, I really don’t know what’s going wrong so that’s why I’m posting it here.
Obviously the expander had to take too much current (without cooling you can’t go over 10A). Or there’s been a short somewhere.
You need to give more details about your set up.
What kind of heated bed do you have? What is the voltage of your PSU? Could you post a picture of the connection on bed side. Is there some isolation between the bed and the alu plate?