Solved (Robo3D R1) Extruder Not heating Past 192~ C

Hey Everyone!

So I've been tasked with repairing a Robo 3D R1 for my professor. It worked very well last year until someone was printing something with ABS, and somehow cracked the extruder tip. Now I have to either go to the maker's space on campus and pay to wait weeks for them to print things, or repair this one. We've received a new extruder tip, and installed it and got to testing it.

Everything seems to work, but the extruder is not heating past 192~ C. I have taken off the bottom plate, ensured all the wires are seated well, and I've re-seated all them, making sure none of them are loose or had dust or something ruining the connection. I've put the bottom plate back on, and then ensured all the wiring at the top is connected correctly, we plug it in, and everything is working just fine, heat bed works just fine, I can control the position of the extruder just fine, and everything else is just dandy. The only problem is I can't get the extruder tip to heat past 192 C.

I have read that some people with a similar problem claim it was a problem with the thermistor. I'm not sure where that is located, or what it's supposed to read at if I took a multi-meter to it.

Any help would be greatly appreciated


Edit: after doing a time bit more of testing, it's only reading at around 192 C.

 

After plugging it in after being at room temperature it's reading at 191.8 C

 

This sounds familiar.
Are you saying at room temperature (no printer job running, no pre-heating set) it is reading 191.8C?
Is it actually hot? Be brave and feel if there is any heat coming off it (don't touch it if! it WILL raise a blister).

I had a bad thermister after changing my first nozzle. I inadvertently busted the wire going to the thermister (it is the smallest of the two wires going to the print head. It was fine before I changed nozzles and I broke it myself learning how to do it.

I took the thermister out and it read about 0 on the meter. New one read 100 or so.

I've busted 2 thermisters, it's easy to do until you learn how delicate they are.

 

No Heat is coming off of the extruder. I just triple checked, and all the cables are attached in the right area. Even after unplugging the thermistor it's reading at ~192 C in Matter Control. So i'm thinking it may be a software problem, this printer is older.

I've attached a picture of the hotend, not the best picture but I've only an older cell phone.

I've taken off the plastic on the hotend, and ensured that the plastic sleeves on the thermistor is preventing any shorting out, and ensured that it is where it is supposed to be.

I'm not 100% sure how or why the tip cracked, but since it broke maybe the thermistor is also broken.

 

Thanks for all the replies and help so far!

I talked to my professor, and double checked, the thermistor has definitely shorted, and hopefully that is the only problem, after checking everything else, the only other thing that could be broken is Arduino inside the printer, but one step at a time. My professor said he was a bit rough with the thermistor when he was replacing the hotend, so it's likely that's the problem.

So my professor asked me to get information on who to contact at Robo, and so i'm back here, if my only option is the Contact Us button at the bottom of the web page, we'll do that.

For now we're reaching out to some people we know who may have extra thermistors, and replace those ourselves if we can find them.

 

Hey, updating with more information.

Replaced the Thermistor with a brand new one, and it's still reading extruder temp around ~191 - 192 C.

The bed temperature still works, and everything else seems to be working, so I'm wondering what else could be causing this reading?