Strange behaviour - Heated bed
Posted by zitman
|
Strange behaviour - Heated bed August 22, 2016 03:55AM |
Registered: 9 years ago Posts: 60 |
I recently had some issues with Thermal Runaway (Thread) which I thought had gone away.....
Friday evening I was printing some items when I realised the printer had stopped, when I checked it was displating "THERMAL RUNAWAY" again! I restarted the printer, cleaned the bed and attempted to restart the print via Octoprint and it hung at the bed heating phase. Trying to set the bed temperature via octoprint also failed. The resistance on the bed seemed OK but with the bed disconnected I am only seeing about 2.5V across D8. Up till this point I had been setting the bed heating via Octoprint. I tried via the LCD panel using the Preheat PLA Bed option and it also didn't work but after some probing I found the second extruder port D9 was powered although the first extruder for D10 wasn't. This is making sense to me as I cannot figure out why D9 would be heating when I am commanding the bed to heat. Also stumped as to why the bed has stopped functioning on D8, this happened a couple of months ago to another RAMPS board and I ended up replacing both the RAMPS and the Mega, ending up with the setup I now have. I am using the latest Marlin (as at a couple of months ago) and from when I thought I had sorted the thermal runaway problem until last Friday the printer was working fine.
So can anyone suggest why the heated bed has stopped working (i am assuming blown MOSFET) and why the bed heats when I select the Preheat PLA Bed option but only when attached to D9?
Could I change HEATER_BED_PIN in Pins.h so the heated bed was on D9 to see if this works in Octoprint or is the MOSFET different on the extruder channels as opposed to the bed heater channel?
Z
My blog: 3DR build and more . . . .
Friday evening I was printing some items when I realised the printer had stopped, when I checked it was displating "THERMAL RUNAWAY" again! I restarted the printer, cleaned the bed and attempted to restart the print via Octoprint and it hung at the bed heating phase. Trying to set the bed temperature via octoprint also failed. The resistance on the bed seemed OK but with the bed disconnected I am only seeing about 2.5V across D8. Up till this point I had been setting the bed heating via Octoprint. I tried via the LCD panel using the Preheat PLA Bed option and it also didn't work but after some probing I found the second extruder port D9 was powered although the first extruder for D10 wasn't. This is making sense to me as I cannot figure out why D9 would be heating when I am commanding the bed to heat. Also stumped as to why the bed has stopped functioning on D8, this happened a couple of months ago to another RAMPS board and I ended up replacing both the RAMPS and the Mega, ending up with the setup I now have. I am using the latest Marlin (as at a couple of months ago) and from when I thought I had sorted the thermal runaway problem until last Friday the printer was working fine.
So can anyone suggest why the heated bed has stopped working (i am assuming blown MOSFET) and why the bed heats when I select the Preheat PLA Bed option but only when attached to D9?
Could I change HEATER_BED_PIN in Pins.h so the heated bed was on D9 to see if this works in Octoprint or is the MOSFET different on the extruder channels as opposed to the bed heater channel?
Z
My blog: 3DR build and more . . . .
|
Re: Strange behaviour - Heated bed August 22, 2016 04:33AM |
Registered: 9 years ago Posts: 590 |
|
Re: Strange behaviour - Heated bed August 22, 2016 07:38AM |
Registered: 9 years ago Posts: 60 |
@enif - I don't believe so but will check when I get home this evening
My blog: 3DR build and more . . . .
My blog: 3DR build and more . . . .
|
Re: Strange behaviour - Heated bed August 24, 2016 07:16AM |
Registered: 9 years ago Posts: 60 |
Hi @enif - Apologies things have been a little mad these last two days, Have checked and the MOSFETS are definitely not touching.
Z
My blog: 3DR build and more . . . .
Z
My blog: 3DR build and more . . . .
Sorry, only registered users may post in this forum.