For some reason, my extruder isn’t heating at all on my Taz 4. There weren’t really any events that happened before this fault that would make sense as a reason for it to stop heating, and I’m looking for some suggestions on troubleshooting this issue. I do have another taz 4 at work that I’m going to try putting my extruder on to. Hopefully this helps me narrow it down to it being either the heat cartridge on the extruder, or the actual controller.
If you have any suggestions I would be very appreciative!.
What does the temperature reading say on the LCD?
You can start by double-checking the connections. Those are possible failure points.
Since you’re going to disconnect it, if you have access to an ohm meter, you can try checking the heating element and the thermistor.
The heating element is a 4.7 ohm resistor, so you should get a reading in that area. The heating element is the front device in the heating block, and on mine it’s connected to the red wires in the connector. (If you’re using a typical low - medium cost multimeter, then also measure the resistance of just the test leads by touching the probes together tightly, and subtract this from your reading of the resistor.)
The thermistor is a resistor that varies value depending on its temperature. It provides the temperature reading and feedback to the controller. It’s connected to the orange wires in the connector. I believe it should be roughly in the area of 80K ohms (80,000) at room temperature. If you heat it up by breathing on it, you should see the resistance drop toward 70K ohms. (But that’s if you take it out of the heater block. You’ll have to use other means to heat it if it’s still in the block. If you see a normal room temperature reading on the LCD, then the thermistor is probably OK.)
If either of these are open, check the connections between the connector and the devices to see if anything came loose. Lulzbot stocks both as replacement parts.
Thanks for the fast reply!
I did check the connections multiple times with no luck.
Thanks for giving my the resistance across the heating element, I’ll check that tomorrow on my meter.
I assume my thermistor is OK since it is reading temperature correctly.
Thanks again for the help! I really appreciate it.
Once you can confirm that the heater resistor is not reading appropriately, contact support at Support@LulzBot.com with your order information, your 3D printer serial number, contact information and shipping address. Replacing the heater resistor is easy, if you can confirm that’s the cause we can send an easy to replace, prepared heater resistor assembly.
Did anything happen prior to the hot end heater failing?
Just an update.
I did replace the heating resistor, and everything works fine now.
Thanks to everyone for the help!
After about 100 hours or so of printing, it’s happened again! It’s very frustrating. I feel that a more robust solution may be necessary.
It’s not normal at all to need another heater resistor, as they’re not consumable. Mind taking a look at the hot end, and the spacing between the heater resistor and the heater block? How much play is there between the two?
this same thing happened to me, the nozzle stopped heating up, I replaced the little heating tube that slides into the aluminum block, and it worked just fine! for about 100 hours, now its dead again 
am I doing something wrong here? seems a bit weird to have two burn out in a row.
it was working fine until I moved the x axis on the nozzle a bit to much and turned the switch off so it wouldnt work its way off the end of the long screws…
when I turned it back on, the heater was no longer working.
I replaced my heater and it also broke in about 100 hours.
Seems like Lulzbot is selling JUNK replacement parts. The first heater that came with the printer lasted about 1000- 2000 hours. the second heater last hardly 100 hours. Really Lulzbot?? I pay extra for premium parts. I got junk instead.
Last time I buy junk. Now I am down for a week until I get the part in.
The heater is not reading any ohms at the resister.
Or maybe you just suck at installing replacement heaters?