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MMU Overcurrent #13310 (MK4) #21310 (MK3.9) #23310 (MK3.5)

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Last updated 4 months ago
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What happened?

The MK4/MK3.9/MK3.5 xBuddy board is equipped with a safety mechanism to detect power supply overcurrent situations in the connection to the Multi-material unit (MMU). Upon detecting overcurrent, the printer automatically cuts off both power and communication to the MMU unit as a preventive measure against damage.

I don't have an MMU installed

If you haven't installed an MMU, make sure to disable the MMU functionality in the printer's menu in Settings -> MMU Enable. However, if you still face this issue with the MMU option being turned off, it might indicate a damaged component on the xBuddy board. Please reach out to Customer support for assistance.

How to fix it?

The MMU unit should not be connected or disconnected during regular use while the printer is running.

Inspect the MMU, Printer cable, and PD board for any signs of damage. Check the cable's path to the xBuddy board for any broken or pinched parts.

If there's no visible damage, ensure the cable connections to the MMU PDU and the xBuddy board are secure.

To troubleshoot, first disconnect the MMU cable from the xBuddy board, go to the printer menu in Settings -> MMU Enable and set the MMU to off. Verify if the printer operates correctly with the MMU unit disconnected and the MMU functionality turned off. After confirming this, reconnect the MMU and test the printer with the MMU turned on.

In rare cases, this error message might be shown due to a damaged xBuddy board. Try checking the board for any signs of damage.

When contacting Customer support about this issue, it's crucial to specify not only what firmware and hardware are you using, but also the version of your printer's xBuddy board (e.g., 0.2.7 / v36, etc.), as there are variations in the electronic diagrams across different versions.

Technical information

The xBuddy board is constantly monitoring the current flowing through the electronics. If the power draw exceeds 3.6A on the MMU connector's power line, the printer will display this error, and the corresponding LED indicator on the xBuddy board will illuminate. A potential overcurrent condition is likely to occur after the first startup, as power demand peaks while capacitors are charging. 

The xBuddy board is designed with the capability to fully manage power delivery to the MMU unit, incorporating a software feature to mitigate such overcurrent scenarios. However, this function is specifically calibrated for the original MMU3 unit. In certain unsupported hardware configurations, this may result in a false error indication.

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