Hey everyone!
I could really use some help with a problem I’m having on my 3D printer — I’m kind of stuck and hoping someone here has seen this before.
- What happened:
Until a few days ago, everything was working perfectly — I printed lots of projects without any issues.
Last night, the extruder got clogged, so I followed a tutorial to clear the filament, reassembled everything, and it was working fine again.
This morning I installed a new enclosure (super excited about that!), no problems at first.
- The issue now:
When I start a print, during the homing process, the extruder moves all the way to the left and makes a grinding noise.
The motherboard fan also makes a weird noise for a couple of seconds, then stops.
As soon as the extruder reaches the left side of center, everything freezes, the printer shuts down, and I get this error on Klipper:
MCU 'extra_mcu' shutdown: Weight read error
Once the underlying issue is corrected, use the
"FIRMWARE_RESTART" command to reset the firmware, reload the
config, and restart the host software.
Printer is shutdown
Klipper state: Not ready
- What I’ve tried:
Of course, I’ve already tried running FIRMWARE_RESTART several times, but no luck — the error keeps coming back right away.
- Questions:
Has anyone run into this before?
Could it be related to the enclosure (like heat, pulled cables, interference)?
Or am I looking at a hardware problem (maybe motor, endstops, or the motherboard)?
Any suggestions on things I should check before I start tearing it all apart?
Thanks a ton in advance for any advice or ideas! 
Never seen these errors but there are a couple clues here
The “extea_mcu” is the printhead
The use of the term “weight” leads me to believe the issue is with the loadcell
On the Ace the hotend (nozzle, heatblock, and heatbreak) are mounted on a force plate.
Make sure the wires are connected
Make sure nothing is touching your hotend
Long shot - Make sure the hole in the bottom of the extruder is clean. To function correctly the heartbreak needs “wiggle room”. The hole in the extruder is 7.0mm. The outside of the heatbreak is 6.7mm
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Thank you so much for the detailed reply! That’s really helpful.
I’ve checked the loadcell connections and made sure all the wires are properly plugged in. I’ve also inspected the hotend to confirm that nothing is touching it.
And good tip about the extruder hole — I already cleaned it, so the hole is totally clear and the heatbreak has room to move.
Unfortunately, despite all these checks, I’m still getting the same error as before.
I’m attaching a short video so you can see exactly what’s happening. Hopefully this helps to diagnose the issue!
https://imgur.com/a/NTOvQ7U
@sovol3d Time to get Solvol support involved.
Probably a damaged load plate.
If you have an ohm meter, UNPLUG the loadcell and measure the resistance of the bridge.
red/black should be 1000 ohms
Green/white should be 1000 ohms
Not that it matters but you can figure out exactly which of the gages is bad by measuring the other 4 combos. All the other combos should be 667 ohms (1000 is parallel with 3000)
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Thank you so much for this helpful and detailed reply — I really appreciate it!
At the moment, I can’t measure the resistance because I don’t have a ohm meter, but I just ordered one on Amazon. As soon as it arrives, I’ll follow your instructions and hopefully get a good result.
Also, if you can provide any additional details, an example, or even a photo of how to do the measurement, that would be really helpful — this is actually my first time using a ohm meter!
In the meantime, I also emailed Sovol support, but I haven’t heard back from them yet.
Thanks again for your help!
Hi!
Thank you so much for your help and the detailed explanation. I just finished measuring with the multimeter, but every combination I tried gives me 0L on the display.
So:
- Red ↔ Black → 0L
- Green ↔ White → 0L
- Red ↔ Green → 0L
- Red ↔ White → 0L
- Black ↔ Green → 0L
- Black ↔ White → 0L
To make sure I was measuring correctly, I asked for some help since this is my first time using a multimeter, and it was a bit confusing at first.
I tested both with the printer on and off — same result.
And yes, the multimeter works because I tested it on a metallic object, and it gave a proper reading.
Do you think this confirms the load plate is damaged?
Thanks again for all your help!
One more thing: when I disconnect the loadcell cable, the printer actually completes the homing without giving the MCU error — but of course, the nozzle crashes into the bed.
Post a photo of the front of your meter.
My guess is that you are using it in 200 ohm mode. 1000 > 200 so it reads OL
You need to be in in 2k or 20k ohm ranges
https://imgur.com/a/KvpQuHj
thank you a lot for your help
Meter is in fact auto ranging so that’s not the issue
Your probes seem a little blunt. Are they touching BOTH terminals. You can either use 2 small pieces of metal inserted into the connector or release the terminals from the plastic connector.
Use caution not to bend the terminals. Paper clips are an old school go to for probe extensions but are too fat for this connector. Sewing pins or 2 nozzle cleaning cleaning needles.
Thanks again — I followed your advice and used thin pins to measure, and now I’m getting these results (in kΩ):
- Red ↔ Green → 1 kΩ
- Red ↔ White → 1 kΩ
- Red ↔ Black → 2 kΩ
- Green ↔ White → 2 kΩ
- Green ↔ Black → 3 kΩ
- White ↔ Black → 1 kΩ
Do these numbers tell you something about what’s going on?
Thanks again for your patience and help!
When I disconnected the cable you told me to measure, I noticed something concerning: there’s a lot of glue around those pins, and looking closer I realized the pins are visibly burned. When I carefully removed some of the glue, I even saw a thin metal wire that came off — it probably detached from one of the pins.
Yes. 1 of the 4 gages has failed inside the load cell
You need a new load plate.
That your machine no longer errors with the load cell unplugged tells me the circuitry involved with reading the load cell is PROBBALY okay.
The glue is to prevent connectors from vibrating loose during shipment. Peel off what you can and don’t worry about it
Hi,
thank you so much for the clarification!
It’s very helpful to know that one of the gages inside the load cell has failed and that the rest of the circuitry is probably okay.
I’ve already written to Sovol support, and I hope they will send me a replacement load plate — at least that way I won’t have to replace the entire machine.
About the glue: just to make sure — I should peel it off after I install the new load plate, right? Do you think there’s any risk that something could come loose or get damaged when I remove it?
Thanks again for all your help and explanations — it really made a big difference!
One more thing. The fact that no wire is open proves the failure in in the strain bridge not the lead wires.
Did you accidently peel off the cover (green in the CAD model) while cleaning after your “clog”?
Strain Bridge schematic looks like this. Green ↔ Black → 3 kΩ
Shows that R2 is open
Hi,
first of all — that circuit diagram is awesome! Where did you get it from? It’s really impressive.
Thank you once again for this incredibly helpful explanation and the diagrams!
I was actually very careful during that process.
But now that you mention it, maybe something got stressed or damaged without me noticing. Anyway I followed this video very carefully and stuck to the instructions exactly because this is my very first 3d printer so it’s very important to me.
https://www.youtube.com/watch?v=HXkaupU9vGM&ab_channel=Sovol3DSupport
Your explanation about the strain bridge and the lead wires really helps me understand why the failure is inside the load cell itself and not in the wiring.
It’s great to have this confirmed.
Thanks again for all your help — I really appreciate the time you’re spending to guide me through this and all the details, you’re an angel
