Hi everyone!
During the replacing of one of two damaged printheads on my K8400 I must have shorted something as all of a sudden the heaters started heating up uncontrollably (like a thermal runaway). Whenever the printer is powered the red lights on the printhead come on and it heats up, up until the point where everything starts smoking (ignoring the MAXTEMP 275C warning).
I have the feeling either the mainboard (VM8400MB) the individual drivers are broken (VM8400DB?).
Things I have tried:
• Using different extruder board (P8400EXTED) but on this one the two red LED’s also light up
• Unplugging drivers on the mainboard, same result
• Reflashing firmware. It performed this without problems however the uncontrollable heaters remain. I can also still control the printer like normal. Just the heaters are uncontrollable.
I have ordered a new VM8400MB and 2x VM8400DB to be sure. I am not sure these control the heaters as well or whether it is just the stepper motors. All stepper motors work fine
Does someone know what exactly is broken if the heaters are constantly on?
Any advice in what order I should replace the mainboard?