PD-Board Issue (Overcurrent/Overvoltage)
Hi,
before I recieved the PD-Board for my Upgrade from MK3s+ to MK4 I was struggeling with undervoltage for the 5V VCC (well known Issue)
Since I have the PD-board, the situation is vice-versa. At the final power up was everything ok, even the first prints. Then I switched the printer off and 20sec later I swiched on agian, the the printer restarted and showed the error that at the MMU port an overcurrent happend.
At this point, the message was persistant, so I removed mmu cable at the xBuddy > No Error. After reconnect, the error happens again.
I removed the connector of the MMU cable from printer at the PD - Board > no error, also no error happens if only the PD-Board is connected to the Printer.
Once the PD Board is connected with the MMU, then the error happens again. The Error also appeard if All stppers were disconnectd from the MM-Control Board.
I checekd if an unexpected low resistance (short circut) could be measured at the Input Connectors, but everything normal. (all min. 10k)
Then I stopped diagnostic and resumed one day later, and the Issue was gone... everything okay again.
Precautionary I also inspected the complete cable from Printer to MMU but couldn´t find any defects...
Some days later, the same behavior happens in the same situation, after successful print I powerd the printer down and back on >> Error MMU Overcurrent, persitantly, like at the last time.
This time I measured the 5Volts Supply at the disconnected PD Board at the socekt to the MMU. It was 5,78 Volts!! For my understanding more than 10% Overvoltage could be critical to some components...
Then I decided to power the MMU with an 5 Volt external power supply, like I did with MK3s and the undervoltage behavior.
Now everything is fine again, no error messages, everything is working.
@All, did anybody measured the 5 Volts output from PD board and observed an identical behavior?
Greets, Thorsten
RE: PD-Board Issue (Overcurrent/Overvoltage)
Hi Thorsten,
unfortunately we have exactly the same problem, after the upgrade to MK4. First prints were fine, but then it started with the overcurrent error. We checked all the connectors, cables and boards, everythings fine as it was before. We have smiliar voltage messurements.
So, can anybody help?
Greetings!
RE: PD-Board Issue (Overcurrent/Overvoltage)
We just took again messurements. At boot-up start, it,s 4.95 V and right before and during the MMU test it spikes up over 5.75 V. We assume that's the problem.
So, Prusa Team can you help?
Greetings!
RE: PD-Board Issue (Overcurrent/Overvoltage)
together with other people we are discussing the same bug on GitHub, a temporary solution is to leave the usb cable plugged into the MMU3 (no need to plug in the computer, just find a place to leave it be without obstructing the printing operations).
It’s not elegant but prevents the overcurrent creating a very very small delay in the MMU booting!
RE: PD-Board Issue (Overcurrent/Overvoltage)
Thanks for the Information @Pars3c, can you provide the link to the GitHub Issue?
And when I get this right, the Cable is just Plugged into the MMU, nothing else?
RE: PD-Board Issue (Overcurrent/Overvoltage)
RE: PD-Board Issue (Overcurrent/Overvoltage)
for me, I completely fixed that issue and having no more issues or other artifacts since that.
I added a 1Ohms, 1Watt resistor in every red wire (+24VDC) ( so the all over resistance is 0.5Ohms, cause the two red wires are parallely. )
that solution (current limiting resistor) is very common, don’t know, why Prusa didn’t done that for the 24v. For the 5V they did that solution.
current limiting resistors has a lot advantages, if calculated well, in normal condition the resistor has no impact, the voltage drop is here 0.1-0.2v (@24V)
In high current or error behavior that resistor helps to avoid other defects like burned semiconductors….
Greets Thorsten
RE: PD-Board Issue (Overcurrent/Overvoltage)
Same issue here MMU overcurrent on boot prusa sent replacement main board mmu board pd and cable still not fixed
RE: PD-Board Issue (Overcurrent/Overvoltage)
Just tried this and it's worked so far! Thanks!
for me, I completely fixed that issue and having no more issues or other artifacts since that.
I added a 1Ohms, 1Watt resistor in every red wire (+24VDC) ( so the all over resistance is 0.5Ohms, cause the two red wires are parallely. )
that solution (current limiting resistor) is very common, don’t know, why Prusa didn’t done that for the 24v. For the 5V they did that solution.
current limiting resistors has a lot advantages, if calculated well, in normal condition the resistor has no impact, the voltage drop is here 0.1-0.2v (@24V)
In high current or error behavior that resistor helps to avoid other defects like burned semiconductors….
Greets Thorsten
RE: PD-Board Issue (Overcurrent/Overvoltage)
This bug is still open in github it seems. Has anyone heard from support if they've come up with a solution to this? It bothers me that I have to touch the board when booting to avoid the BSOD.
RE: PD-Board Issue (Overcurrent/Overvoltage)
I added a 1Ohms, 1Watt resistor in every red wire (+24VDC) ( so the all over resistance is 0.5Ohms, cause the two red wires are parallely. )
I had the same annoying overcurrent issue and inserting 1 Ohm resistors into each red 24V wire did solve it instantly. Thanks a lot for the hint!
RE: PD-Board Issue (Overcurrent/Overvoltage)
Having the same issue, fixed it by adding the resistors. I´m actually very disappointed, for an over 1000€ product...
RE: PD-Board Issue (Overcurrent/Overvoltage)
@willgiam,
but thats no point to be disappointed, if it is fixed, espacially if fixed by yourself.
I also did my "lessons learned" DIY seems to be the center feature and requierment, to the printer and the owner.
So my Mantra with my existing Prusa products are: "Don´t expect to get your issue fixed without own investigation" (next products will be something other)
But if you having an MK4 and MMU, then you might also have jamming/stucking filament in Extruder on loading and unloading... If you searching for help or solution, take a look here
RE: PD-Board Issue (Overcurrent/Overvoltage)
As an electrical engineer I have to say that I´m disappointed by Prusa, because this error is existing since Apr 2023 if I see it right on github and it can be easily fixed. It seems like the circuit on the PD board just needs a revision. They have theyre own production of these boards and the newer charges would not have this problem.
I have my DIY projects, with my own designed printers. The Prusa was always my mule and just has to work.
All my MK4S and MMU are working fine apart from this. Only detected jams are really annoying, but only while printing.
RE: PD-Board Issue (Overcurrent/Overvoltage)
As @WillGlam says, from an electrical point of view this was avoidable.
Onvd I figured what exactly the power connector is called (the type and the component code) im planning to provide a small PCB Board for everyone who want a plug and play fix.
Basically you plug the Prusa MMU power connector on these and the PCB will be connected to the MMU
RE: PD-Board Issue (Overcurrent/Overvoltage)
@willgiam,
understand.
You mean, after a certain time, the extruder stops to extrude filament, shows no error and Gear is still rotating? Yes, thats also covered by my solution, I also had that often...
your ejected filament looks like this?
the reason for that is the force, that needs to be applied to the idler to get it working, but that is the Problem, because the original R2 Mainplate has an design issue, close to the idler hinge is a edge that limits the idler movement. If you apply the correct force, the gap between Bearings and pulley is too large to apply the correct force, which results in grinded filament.
If you apply just a bit more, the Idler will be bend and twisted over that edge and results in sidewise bended filament, which then also results in grinded filament, espacially if you print in an enclosure where the ambietn temp is higher.
RE: PD-Board Issue (Overcurrent/Overvoltage)
Thats actually not the problem I was referring to. It was more, that he is detecting clogs where are no clogs. But I´m getting used to it. But lets get back to the actual problem.
RE: PD-Board Issue (Overcurrent/Overvoltage)
the connectors are: called Clickmate 502578-0400 Molex
RE: PD-Board Issue (Overcurrent/Overvoltage)
but if you are searching the connectors on the MMU bard (black) they are Molex SL 70543
RE: PD-Board Issue (Overcurrent/Overvoltage)
Hi, I have a CyberMonday MK4s/Mmu3 on the way, so I hope this gets resolved soon! I see lots of ideas being thrown around but no concrete solutions yet.
This looks to me very much like a grounding issue. Has anyone tried bonding the MMU board to the xBuddy? By that I mean, attach a green/yellow wire from the xBuddy PE terminal to one of MMU board mounting screws, similarly to the way the xLCD and PSU are connected.
Any Prusa engineers here?