PCB adaptions for Mendel

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Replacing the connectors on the stepper driver boards

The RJ45 connectors are low-cost, as is the cabling for them. But they are not very neat. To replace them do the following.


Use a pair of tweezers to pull the gold-plated connectors inside the RJ45 shell and push them up through the top. Then pull them out from the top and straighten them out.


Next desolder each connection separately, pulling it out with long-nosed pliers. The plastic shell will then be easy to remove.


This shows all modified connectors. The original is on the left; the modified is on the right. The two RJ45 connectors have been removed as above. The bottom one at A - the MIN connector - has been replaced by a 3-pin 2.54mm-pitch pin-strip connector. The RJ45 connector just above A - the MAX connector - has also been removed, but Mendel doesn't use this so you can leave it there if you like.

The power connector (at B) has been replaced with a two-way 5.08mm-pitch screw connector. The other two power connections are not needed. This allows the 12 volt power wires to be permanently attached to the board with the screws. The ground connection is on the left in the picture, and the +12v connection is on the right next to the capacitor. Removing the power connector is the only difficult operation that needs to be done on this board. The only way to do it is to clamp the board, put a small screwdriver under the connector at one end, desolder the connection and lever the connector slightly away from the board. Hold it away while the solder freezes. Then move on to the next connection. By working back and forth between the connections in sequence you will eventually be able to remove the connector. Don't forget allowing the solder to freeze - this puts the next connection along under tension for the next step. Make sure the solder is fully-melted before you start levering, otherwise you may strip the copper from the PCB.

The stepping-motor connector (at C) has been removed and replaced by a 4-way 3.81mm-pitch screw connector. To remove the original connector grasp place the board in a vice clamping it so that the jaws just cover the letters A B C D on the board. Then desolder each pin separately and pull it out with long-nosed pliers. The plastic spacer will come away with the last pin.

You can just put the motor's wires straight in the screw connector without needing to put a corresponding connector on them. Do tin the ends of the wires first, though.