V3 Thermistors read room temp for a few seconds on start and then DEF

[WLJayne]

Hi guys,

I have a problem with my thermistor readings having just uploaded all the firmware. When I power up the printer, the thermistors seem to read around room temp for about 17 seconds and all seems well, but after that they both read DEF.

I'm guessing this means that the connections are ok, so where else could the problems lie?

Thanks .

[geneb]

What values are the thermistors reporting?

g.

[WLJayne]

They jump around a little, but the bed reads about 17 and the hotend reads 19. Room temp is about 19, but it's colder near the floor as this room isn't very well insulated and the weather is very cold at the moment so I'm not surprised there's a difference.

I've moved it onto a table to see if that brings the readings closer together.

EDIT: The readings are much closer now but still fluctuating by 2-3 degrees. It took much longer to get the DEF message this time. How odd.

EDIT 2: Ok now the DEF message seems to be cleared up - perhaps the RAMBO doesn't like differences in ambient temp? However it's still fluctuating within 2-3 degrees.

[Xenocrates]

It's not that. The Rambo is set to a minimum temperature of 18C or so. If the readings are stabilizing below that, then the firmware reads the thermistors as defective and shuts off. My suggestion would be to make sure your printer is kept warmer than that, as it will adversely affect the print quality (extreme warping with ABS, difficulty maintaining temperatures, ETC.)

[WLJayne]

Yes that makes sense, it's fine now that it's on the table. The temps still fluctuate a little on the LCD but appear to be stable in mattercontrol. Now I just need to figure out why it isn't doing anything when I print the V3probing gcode. It returns the hotend to the top when I click cancel but other than that nada.

One thing at a time :/.