screen says def?

[burro breath]

So I printed out a cup holder last night and woke up this morning and it was done. But now the printer wont print and when I restart the printer the screen says what temps the bed and nozzle are for about 2 seconds. The bed says 20 and the head says -18 then after 2 seconds the numbers go away and the word def appears. What is the issue and how does one go about fixing it.

[DavidF]

it does that when you have lost connection to your thermistor....

[mhackney]

The issue is that the firmware can not read the thermistors. This happens because of a software config issue, defective thermistors, a bad port/s on the RAMBo board or a bad connection or short of the thermistors. My bet is on the third reason. Check your connectors on the Rambo board (but be careful, they are EASY to short - I've had to have 3 boards repaired because of my impatience). Also check that the wires coming out of the hot end are not shorted.

An easy way to diagnose...

In Arduino in the Configuration.h file, change this:

#define HAVE_HEATED_BED true

to

#define HAVE_HEATED_BED false

Then recompile and upload. This will disable the heated bed and allow you to focus on the issue if its with the hot end thermistor (which it likely is). Once you have temp working for the hot end, re-enable the bed and it will probably work too. If not, debug it.