[BFW-5572] [BUG] "Heatbed port overcurrent" error when starting to print

[EEJoshua]

Printer type - Prusa MK4 Kit

Printer firmware version - 5.1.0 stable from site

Original or Custom firmware - Original

Optional upgrades - None

USB drive or USB/Octoprint Sending print from PrusaSlicer over Ethernet, using original USB drive that came with it

Describe the bug Every once in a while I send a print from PrusaSlicer, it goes through, the printer suddenly restarts and I get a "Heatbed overcurrent" error screen and beeps. Restarting the printer makes it boot regularly, but if I try to start the print manually from the USB drive it happens again and again. The only way to escape this is to go to Control menu and turn up the heatbed temperature manually. No need to wait for it to warm up, just setting it to something high solves the problem and the next print starts as expected.

How to reproduce Not sure, it happens every once in a while on it's own.

Expected behavior The print should start normally, without restart and error.

G-code It happens with different print files, recently with the attached file. Venchy_0.4n_0.2mm_PETG_MK4IS_1h14m.zip

Crash dump file No crash dump file after restarts

[Logicwax]

I have this same issue. Very annoying. Hopefully there's a firmware fix for this soon.

[shledge]

Have this issue from time to time, it only goes away when I manually set temps.

[github-actions[bot]]

This issue has been flagged as stale because it has been open for 60 days with no activity. The issue will be closed in 7 days unless someone removes the "stale" label or adds a comment.

[zpeters]

Did anyone in this thread find a solution? I recently assembled a mk4 from kit and am experiencing a similar issue. All self tests (including heating the nozzle and bed) complete. However the provided prints (haven't tried others) will reboot with an overcurrent error as soon as the print starts. One time i was able to get a print partially started by pre-heating the bed and nozzle first.

After talking with support they are suspecting the power cabling for the heatbed. If this ends up being a resolution i will report back.

i believe this to be some sort of hardware issue but i wanted to post here in case anyone found a better solution

[danopernis]

I was digging into this some more and here is what I have found: There are two "overcurrent" protections: heater and input; heater is related just to the nozzle, input is related to the entire printer. input overcurrent protection fires faster than heater so the error message you are seeing is misleading. The team responsible for documentation was already notified and hopefully they will change the documentation soon.

This doesn't solve your issue, but perhaps sheds some more light on what is actually happening. I too believe this is a hardware issue.

[shledge]

I haven't had this issue since. I've tightened any contacts and reseated fuses, so hopefuly that might have fixed it.

However, the only thing I can think of that might still cause it is the fact I recently noticed the connector for the hotend has lifted slightly from the loveboard PCB. Likely yanked it by accident at some point. It worked fine despite this. I've glued it back down and reflowed solder which should prevent any further issues, but I also got a replacement loveboard in case it rears its head again.

[zpeters]

just to keep up with my saga. Replacement power cables did not resolve my issue. We are trying a new xbuddy board next

[zpeters]

For my issue a new Xbuddy board fixed it. Comparing the good and bad board there are no visible defects or differences. Hardware rev was : rev37|2023

[danopernis]

@zpeters can you please share more info? How often did you get the warning before vs. now? Were there any typical actions that would lead to error?

While as a firmware developer I appreciate that in the end it was hardware issue after all, I would still like to hear as many details as possible.

[zpeters]

Absolutely! I tried 6.0.2 and 6.0.3 of the firmware with the same issues. The trigger was any time the nozzle heating and bed heating were initiated at the same time. Aside from a few "random" instances i was able to get this to repeat consistently.

Here is how i could trigger it:

• Run the self test for the nozzle/heatbed
• Pre-heat for PLA (i did not try other filament settings)
• Attempt a print

Typically with the selftest, i would get a reset on the heatbed testing stage. For the PLA preheat it was an instant reset. For the print it was often (90% of the time) as soon as i clicked the "play" button. Once i was able to lay down the first layer, but that was maybe 1 time out of dozens of attempts.

If i were to "manually" heat the nozzle then the heatbed i was able to get both up to temperatures higher than a standard PLA setting. By doing this i was able to start a print (the provided gcode for the keychain) but this only lasted until the 2nd layer.

I hope these are good details. Please pick my brain for more!

[aeonik]

This error currently happening to me as well. Though this error began appearing while I was cleaning the nozzle during its heating phase. I was using a paper towel with 80% Isopropyl Alcohol. I can no longer get the printer working, this error "Heatbed Overcurrent" error message appears every time I try to increase the Nozzle temperature now. I can trigger it reliably, 100% of the time, and also means my printer currently does not work...

I started probing the circuits with an oscilloscope, and the heatbed does not seem to be getting any spikes in current nor voltage. In fact it works just fine when I start heating it by itself.

If I turn the the temperature up on the nozzle however, the Mk4 reboots crashes and displays this error message for me.

What's weird is I can manually power the hot end with a power supply after being disconnected from the rest of the printer.

I am currently unable to print, and without any more information or schematics, I am not sure how to collect more data for you all to narrow down the issue.

Regards, Aeonik

[Logicwax]

I was able to resolve this by convincing prusa to ship me a replacement xBuddy board. Once they did that, I've never had the problem again.

[CaveRenderPro]

My MK4S shows this error message if I start printing directly. After a filament change or a short heating time, printing works without problems. Please also checkout all comments of this article for more information https://help.prusa3d.com/article/heatbed-port-overcurrent-26309-mk4s-13309-mk4-21309-mk3-9-23309-mk3-5_405612