3D Printer Tipps&Support Lounge

So i know this might not be the Right forum for this^^ - i dont care.

:arrow_up: This is Ouzo - She lives together with me since some years :arrow_up:

I got some Problems with my anycubic I3 Mega.

Some days ago i noticed a really bad smell while printing - i stopt the print and did sothing else because i had no time for it.

Today i turnd it on - and told it to preheat to PLA Temp (190 Celsius)

Some minutes after it started to smoke out of the hotend.

The PLA on the hotend turned to a black crumb.

So i let it cool down :slight_smile:

Now what to do?

The Thermistor is still in the hotend - no obvious damage to the cable…

Do you manage to unscrew the nozzle? (might need to heat it up first, or else its probably too tight) then, try to drain the rest of the remaining gunk.

I had a similar issue with my prusa, and it was a ‘leak’ between the inside of the hotend ant the cooling ribs.
Complete mess. Ended up replacing the hotend, but it’s never really been the same :expressionless:

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Almost certainly a thermistor failure leading to thermal runaway (due to the smoking + charred PLA). You can confirm this by turning on the printer, and observing the listed current temp of the hotend. Will likely show some nonsense value. There’s usually no visible signs of failure to the thermistor itself. Essentially, the printer doesn’t know what the temp is, and keeps trying to pump more power into the hotend to increase the temp, which wrecks everything. First thing I would do is try to disassemble your hotend. No matter what, you likely practically vaporized your PTFE tube, and the charred PLA needs cleaned as well.

When I had this happen, I had to take my entire hotend outside, remove the thermistor and the heating core, then gently use a torch to soften everything enough to remove the nozzle. Then I was able to clean out the nozzle properly.

If your thermistor is working, then see answer above :arrow_up:


I agree with darthdomo sounds like a therm runaway

Which brings up an important question/point

We should be making sure these printers have thermal runway protection enabled to prevent fires

Other option is, the mosfet could
Have failed in a closed posistion so it doesn’t matter what the board tries to do

I checked the Printer to observe the Temp reading - as soon as i turnd it on it starts with 7celsius - instantly it rises - after 20 sec it was at 100 celsius -

I didnt told it to heat - i touched the hotend to confirm the temp read - damn was it hot!

Edit: Sounds like the mosfet :frowning:

Yeah, sounds like the MOSFET failed closed.

Out of curiosity, does your printer use the AnyCubic TriGorilla board?

I’ve owned a single AnyCubic printer, a variant of the Kossel. I had my TriGorilla board fail in a similar way, and the board full-on burned.

Wondering if it’s an issue with their boards in general. Regardless, you should be able to contact them and have them send a new board. They did it without hesitating when I contacted them a few years back when mine failed.

I don’t like their products to be honest, I’ve had bad experiences overall, but their support is good.

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I will open it later and check the board


is there a good way to check the board without dissembling the Z axis?

You flip it on its back.

This is a good video, skip to 1:28.



i would just have dissembled the Z Axis :slight_smile: glad that i asked

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Is anyone willing to 3D print something for me and ship it to me? I’d be willing to compensate of course! I don’t have a 3D printer yet, boo

If its fixed i can do :slight_smile:

Yep. Trigorilla board.

Mosfets look fine to me

Since we’re both at Purdue, I could print you something when I go home in a week or so, and just bring it back with me. That way there’s no shipping cost.

That’s odd, tbh I would have expected a more spectacular failure.

If you have a multimeter, and are comfortable using one, I would double check by measuring between the two HEATER0 contacts.

If it’s 12V with the printer on idle, then that confirms the failure.

Maybe it want to heat right after turning in because oft the resume Print thing and the thermistor is Brocken

I was curious if that was the case, but my TriGorilla firmware version didn’t have power loss resume :frowning:

If that’s the case, you should be able to cancel it quickly via the control panel.

Makes me curious when they added that feature, I feel cheated if it was after I bought mine :stuck_out_tongue_winking_eye:

Open - inifinite ohms


Just read that :slight_smile:
If it’s 12V with the printer on idle, then that confirms the failure.

On measuring the thermistor? definitely a thermistor failure + runaway then.

That’s better than a MOSFET fail though, easy to fix, and a ton of documentation online.

I would also recommend later, when you get the printer working, flashing an open source firmware with runaway protection enabled.

Idk why, but a ton of these chinese printer manufacturers leave it disabled. It’s a huge safety risk, and there should really be a lawsuit.

Thankfully it’s fixable with a firmware update.

Where are the thermistor contacts in the mainboard?

Oh, that would be awesome! I’ll DM you the Thingverse’s. Thanks!