Heatbed Thermistor Issues (1 reply)

My printer started going into dry mode because of a heatbed thermistor error. I removed the thermistor and found that it had split. The bad thermistor was replaced with what I believe is the same type of thermistor (both purchased at one time from same vendor, both in same bag, but no data sheets).

With no FW changes, the new thermistor shows -50deg temp - causing default.

New thermistor appears to be working ok (115K at 23deg and goes down when heated).

Using the form provided on the [reprap.org] page, I was able to calculate the Beta value and then used the createTemperatueLookup python script to create a new table.

Using the new table, my heatbed temp is correct at startup but it never seems to change.

I can turn on the heatbed and it does heat, but the temperature reading never changes and the heatbed won't turn off without a reset.

Also, when viewing the Temperature Curve in Repetier, the heatbed output graph does not change when turning on/off the heatbed (like it does when I do the same thing with the extruder).

I have more thermistors on the way but right now I'm not sure if it's a thermistor, RAMPS or firmware issue.

I am testing using version .83 of the firmware because the remarks in the configuration.h file make it easier calculating and setting the thermistor tables.

Thx