Alunar Prusa i3... temp is "def".

[lawndartleo]

Greetings,

Having gone through the hardware check for the Alunar Prusa i3 that I purchased, problems arose with heating the bed and extruder.... they don't, either one. Everything else checks out except these two things. The seller asked for some pictures of the LCD during operation and determined that the "def" temperatures were a result of a bad thermistor. Has anyone else experienced this? Was a new thermistor (or two) the fix? Is there anything else to try?

Controller is an Anet V1.0 board.

[DennisH.]

My printer wouldn't heat either when I first got it assembled. After an hour of troubleshooting I figured out that the instructions were telling me to plug into the wrong sockets. When I figured out the correct ones it heats up nicely. Also one of my extruder motors had to be plugged in a different socket than the build manual and video showed.

[angellina]

My printer wouldn't heat either when I first got it assembled. After an hour of troubleshooting I figured out that the instructions were telling me to plug into the wrong sockets. When I figured out the correct ones it heats up nicely. Also one of my extruder motors had to be plugged in a different socket than the build manual and video showed.

Have u got fixed!!!!!!!

[Charlie1]

the 'def' signal means that the thermistor is not returning a valid signal to the control board. It's either an open circuit or a dead short. Since it falls outside of the acceptable range, the board shuts down the heater circuit to prevent runaway thermal damage.

Note that if either the hot end thermistor OR the heated bed thermistor have a problem, both heaters will be shut down. This can cause you to believe that you have two bad thermistors, when in fact only one is troublesome.

One common problem occurs at the hot end thermistor, particularly on e3dv6 heads. The thermistor is inserted into a hole in the aluminum hot end, the legs bent at 90 degrees, and a screw tightened down to hold the thermistor in place. The leads are typically insulated with a thermal protection sleeve. If this sleeve has slid out of place or become damaged, the thermistor lead can ground through the aluminum hot end, thus providing a bad reading. Alternately, enthusiastic overtightening of the screw can break a lead.

To troubleshoot the problem, check the resistance on the two thermistors with an ohm meter. If either one is reading infinite or near zero, you've found the troublesome thermistor. Check it for signs of visible damage, and repair or replace according to what you find. Hope that helps - Charlie1

[DennisH.]

Yes. When I figured out that they needed to be plugged in to different sockets than the instructions and video shows.

[Chad]

Good troubleshooting. Thanks!
I will add the solution to my machine's "def" error...

Check the wiring in the thermistor terminal connectors at the motherboard, both wires should be on pins 1 and 3 (outer pins). Pin 2 (middle pin) should be vacant, at least on mine.... check the voltage between pins, correct set should read about 5V off the motherboard.