Nozzle heats up when connecting the power cord

Vertex 3D Printer Vertex - Wiring and electronics
1

Hi everyone!

I have tried to find something in this forum, and on the Internet, but can’t find anyone having the same problem.

This morning when I plugged in my K8400, the nozzle started to heat up in an uncontrolled way. I didn’t notice this until I smelled burnt plastic. The computer wasn’t connected, and in the display there were no indication that the heater was on.

I disconnected the heater from the printhead pcb. I meassured the voltage (15V). I disconnected the cable from the main pcb. I noticed that the leds indicating heating are lit on both extruder 1 and 2.

I have reapplied the latest firware (same as I normally use).

I can’t find anything obvious on the pcb. I have disconnected all motors/sensors/display from the main pcb - same thing.

After reconnecting the display - nothing appears on it.

I have been running the printer since a few month back without any major problems (3kg of filament). I have been printing every day for the last week, without any problems what so ever. I always disconnect power cord when leaving the printer for the day.

Faulty pcb? Any suggestions what compontent on the pcb to check?

Regards,

Marcus

2

Does this happen every time you plug it in?

3

Yes - every time.

I gave up on waiting for response. I built a new machine instead. Will probably replace main board with something else, and reuse the parts that didn’t damage during the uncontrolled heatup.

/Marcus

4

Maybe the small pcb on the Print-head has a short between the heater cartridge traces and the thermistor traces. The thermistor has one pole straight connected to the positive side of the psu and the heater is to the negative. Having shorted one negative of the heater with the thermistor might cause this??? Idk I’m just thinking out loud.

Kind regards
JeAfKe