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Trilithon
(@trilithon)
Active Member
Bed overcurrent issues

Hello all,

I have been experiencing a single issue with my MK4 kit. When I start a print with a cold bed I get the overcurrent orange screen. But if I preheat the bed a few degrees and start the print I do not get the error.

Any ideas?

Thanks!

Best Answer by Trilithon:

Prusa sent me a new buddy board and that fixed it.

Original board was marked a rev 0.2.7 2021 (Orange silk screen), the new one is a rev 37 2023 (white silk screen), which matches the 2nd kit that just arrived last week.

Posted : 29/07/2023 5:01 pm
ScottW
(@scottw)
Estimable Member
RE: Bed overcurrent issues

Double-check / reconnect both ends of all the connections for heat bed and power to make sure all are clean and tight.  If those are all good, I'd be inclined to think it could be a bad bed heater.

Posted : 29/07/2023 7:44 pm
Trilithon
(@trilithon)
Active Member
Topic starter answered:
RE:

Thanks for the suggestions, I have already checked the connections. They were tight, but I went ahead and loosened and retightened them and the problem still exists/occurs.

What I do not understand is if I manually preheat the bed a few degrees using the display menu and then start the print either from USB stick or Octoprint, the overcurrent event is not triggered.

Thanks,

Steve

Posted : 29/07/2023 7:49 pm
jvasileff
(@jvasileff)
Trusted Member
RE: Bed overcurrent issues

Yeah, definitely check the connections. But I'd also contact Prusa support. I'd expect over-current to occur when resistance is too low, but a loose connection would actually increase the resistance. You'd have the resistance of the heat bed + the resistance of the loose connection, which would limit the current.

Posted : 29/07/2023 7:56 pm
Diem
 Diem
(@diem)
Illustrious Member

What is the ambient temperature in your workshop?

Cheerio,

Posted : 29/07/2023 7:59 pm
Trilithon
(@trilithon)
Active Member
Topic starter answered:
RE: Bed overcurrent issues

70⁰f

Posted : 29/07/2023 8:11 pm
Trilithon
(@trilithon)
Active Member
Topic starter answered:
RE: Bed overcurrent issues

 

Posted by: @jvasileff

Yeah, definitely check the connections. But I'd also contact Prusa support. I'd expect over-current to occur when resistance is too low, but a loose connection would actually increase the resistance. You'd have the resistance of the heat bed + the resistance of the loose connection, which would limit the current.

This was my thoughts too knowing what I know of resistance and current.

But I did check, loosen and retighten them.

I expected a short instead of a loose connection to be the cause.

Steve

Posted : 29/07/2023 8:15 pm
Darren
(@darren-5)
Member
RE: Bed overcurrent issues

This problem has been noted in the Hardware, firmware and software section under Heatbed port overcurrent. would appear to be a firmware issue, what version are you using?

Posted : 29/07/2023 9:20 pm
Firstflight
(@firstflight)
Member
RE: Bed overcurrent issues

Hello

I have the same problem. As a work around I preheat the bed to at least 60 degree before starting the print. Se my thread: https://forum.prusa3d.com/forum/postid/662902/

Posted : 29/07/2023 9:53 pm
Trilithon
(@trilithon)
Active Member
Topic starter answered:
RE: Bed overcurrent issues

Ok, I may have fixed it.

I went ahead and completely unscrewed the connections on both end, previously I had just loosened them and retightened. I then took a green scotchbrite pad to all 4 of the terminals, both front and back to polish/clean them up as I sometimes do to my R/C battery bullet/terminals.

I then reassembled them and tightened them all back up. I started a print from Octoprint that had previously triggered the overcurrent alarm and it did not.

I still do not understand why preheating the bed by 5-6C and then starting the print would not trigger the OC event?

Steve

Posted : 29/07/2023 10:32 pm
Trilithon
(@trilithon)
Active Member
Topic starter answered:
RE: Bed overcurrent issues

Great! Well not great in the fact we have the error, great in the fact I am not going crazy and only happening to me. 🙂

Thanks for the information!

Posted : 29/07/2023 10:56 pm
Trilithon
(@trilithon)
Active Member
Topic starter answered:
RE: Bed overcurrent issues

Running 4.7.1 that was downloaded 07/12/23.

Posted : 29/07/2023 11:01 pm
Trilithon
(@trilithon)
Active Member
Topic starter answered:
RE: Bed overcurrent issues

Can an admin move this to the Hardware, Firmware, help forum?

Thanks,
Steve

Posted : 29/07/2023 11:11 pm
Trilithon
(@trilithon)
Active Member
Topic starter answered:
RE: Bed overcurrent issues

Polishing the connections didn't help, the error has returned and the only way around it seems to be to preheat the bed before a print.

Posted : 06/08/2023 10:17 pm
kaaassspeeerrr
(@kaaassspeeerrr)
Member
RE: Bed overcurrent issues

Im having the exact same issue since assembly. I was also told to preheat to avoid this error. Preheating does work but starting a print without preheating almost always triggers the bed overcurrent error.

Posted : 17/10/2023 7:29 pm
Livius
(@livius)
Eminent Member
RE: Bed overcurrent issues

I had the same problem.  Checked all my connections, cables, disassembled and reassembled cables and connections.  Error actually increased in frequency. 

The solution is to check the three fuses on the buddy board.  My 10A fuse(heatbed) was extremely loose in its socket.  Turns out the fuse socket on the board was expanded and didn't clamp onto the fuse blades well, increasing resistance and the need for more current.  You can see how open the left terminal on my board was.

Take some needle nose pliers and carefully squeeze the "C" shape of the terminals together to tighten their grip.  Here's what mine looked like after.

No more overcurrent issues.

Posted : 22/10/2023 9:36 pm
dumojac liked
Trilithon
(@trilithon)
Active Member
Topic starter answered:
RE:

Prusa sent me a new buddy board and that fixed it.

Original board was marked a rev 0.2.7 2021 (Orange silk screen), the new one is a rev 37 2023 (white silk screen), which matches the 2nd kit that just arrived last week.

Posted : 30/11/2023 12:14 am
dumojac liked
Logicwax
(@logicwax)
Active Member
RE: Bed overcurrent issues

I had the same exact issue, and support told me it was a firmware issue.......

Turns out it was a defective hotend heater.    I swapped out the hotend with another and my issue totally went away.   I think the printer mis-reports the issue as a heatbed overcurrent issue when it is actually caused by the hotend heater.

Posted : 30/01/2024 11:42 am
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