I was cleaning my printer after a failed print and somehow the thermistor wires from the right extruder crossed (i think), causing them to glow and melt the housing of the wires in the bundle a bit before I shut down the printer (needed it hot to remove plastic after the failed print). I decided to replace the entire hot end assembly for both sides of the printer, but now when I turn it on, it thinks the right extruder is at 751C and shuts down almost immediately. It also says NC for the left extruder. This happens even when I turn on the printer without the hot end wires plugged into the board. There are no physical signs of damage to the board, it seems as though the replacement part is fine, but i cant seem to get it to either read the new temperature sensor or even just detect that the sensor is not plugged in. Does anyone know if there’s a fuse or switch to reset or perhaps what part needs to be replaced?
using a powerspec 3d x aka flashforge creator x from about 4 years ago. Thanks!
It seems, if you have unplugged the hot end wires and your still getting the same error, it sounds like you possible had a voltage feedback to the motherboard, possibly damaging it’s ability to read the Thermistors properly, I’m not sure, but it just looks that way to me.
Damage to chips may not be apparent either.
So if you switch thermisters, and still get a temp error, you have likely blown your FETs, which are chips on the board.
You might have blown the whole board, as can happen, but the least expensive repair is to replace the fets.
They are tiny chips that are surface mounted on the board, and as such will likely need to be replaced by someone who is very good with such things.
Sounds to me like it wasn’t the thermistor wires that were crossed, but the heater cartridge wires, in which case it’s very likely that the FET/s powering the heater have suffered an over-voltage. It’s still possible that, rather than shorting to eachother, one of the wires shorted to the heater block itself, which would have been connected to earth, probably via the motor connections. Must say, a 751C reading does imply that one of the components in the ADC signal conditioning circuit has failed. Probably open-circuit. If you look in the area shown by the photo you may see signs of scorching
Triple-check that everything is connected correctly and start to fault-find and identify exactly which functions don’t work. Swap the heater cartridge connections, right and left, and also the thermistor connections, right and left to narrow down the trouble and make sure there’s no fault off-board.
Lastly, inspect this ares of the control board for any signs of heat, including the tops of the two MAX7767 chips. They may have “popcorned”, in which case the top of tye chip will be slightly domed.
good luck! Hope you manage to trace the trouble and get back to printing quickly! ???
cheers!
Andy
