The predecessors of the Anycubic Mega Hub with ESD protection have all the same dimensions. The differences can be seen below.

The first version still contained the original connectors

I3 MEGA HUB-II distribution circuit board
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The schematic diagram and pinout of the board can be downloaded from here:

• I3 MEGA HUB2 schematic diagram
• Pinout / Pin description of the connectors at the circuit board.

Specially for adding a cable chain to the printer, a further redesign of the circuit board (I3 MEGA HUB3) was made

The improvements are mainly that the connections for the X, Z (right) and E0-steppers (filament) were placed on the right side, making a single cable chain with all necessary wires for the steppers easier to realize. The wires for the left Z-axis are still placed on the left side, as these do not have to be running through the cable chain.

Following up the changes from the second version, further changes and simplifications were made. Most important were to leave out the 3 original red/blue/green connectors and only use D-sub connectors. Also a redundant X-stepper D-sub connection, one on the left and one on the right side, was made. This makes it possible to connect the stepper motor for the X-axis either from the left side (when using a dedicated cable chain), or from the right side (using the standard wiring).

I3 MEGA HUB-III distribution circuit board
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Following files are available of this project:

• ANYCUBIC I3 MEGA HUB-III schematic diagram
• Circuit board outline (for modifying metal case}
• Circuit board pinout description of all the connectors at the circuit board