Printer continues in "dry run" after hardware failure notice

[3DR]

As per the subject my printer is showing this error in Mattercontrol and the LCD displays:-

NOZ: def
BED: def

I have metered the resistance across the 2 thermistor plugs at the Rambo board end and they both measure 145k ohms so I'd say they are ok.

I know the hotend thermistor is ok and working because I can run the PID autotune, it completes without error, its just the LCD display doesn't report the temperature, just stuck on NOZ: def the whole time.

Can anyone help me troubleshoot this?

[Xenocrates]

What is sounds like is that it is quite cold where you are, as the thermistor is supposed to read ~100K at room temperature, and that you're hitting 18 (As measured by the thermistors), which is the low temp cut-out in the firmware.

[3DR]

Ah thanks! that makes sense, I have the printer setup in my loft, and its really cold up here right now, probably the coldest its been this autumn so far, I guess I'll need to explore making some kind of heated enclosure, damn!

[Qdeathstar]

Out of curiosity what gain i say there to continue to move the head about after a hardware failure? is there a way to disable this so that the printer just stops? A month ago i had an issue with this where i was printing overnight and each morning the printer was still moving but no filament was coming out... i thought it was a jam, but nope, my connector from the accelerometer board was loosing causing the printer to go into dry mode... i kind of feel that that is the most useless feature ever.

[IMBoring25]

Some also use an external heat source to initially heat the thermistors above the error threshold.

[3DR]

Some also use an external heat source to initially heat the thermistors above the error threshold.

I did just that, I placed my hand on the centre of the bed just so it warmed from 16ºc to 19ºc and I set the hotend to autotune to heat that up, switched the printer off and on again and bingo we're back in business!

[3DR]

If anyone else gets the same error, before the LCD reverts to def it briefly shows the current thermistor temps, mine were showing as 16ºc so just under the lower limit.

[DeltaCon]

You could adjust

#define MIN_DEFECT_TEMPERATURE 18

to a little bit lower value in the firmware. The trick with the hands won't be needed anymore afterwards.

[kswaid]

Thank god for this thread. I just spent the last 4 hours tearing apart and checking every single piece of my Eris to find the wiring fault that I thought was causing this issue. It turns out that my printer was working fine and the reading of 17.2C room temperature was simply too low. I changed the min error defect temp down to 12C, because 18 is a bit ridiculous. I keep my house around 16C all winter unless I have guests.