MG3 Air assist customisation

The MG3’s default setting is to for the M7 command to drive one electrical output port.

To support customers needing customised air assist operations, a solder and cut jumper selection has been designed into the MG3. Space and budget limitations didn’t allow a full blown electrical port, but this solution can assist tech savvy users to customise air assist.

Cut and solder operation to swap from M7 to M8

The current port is driven by G-code command M7. There is another port behind solder bridge JP2 that uses the M8 command in G-code. The user can choose to use that instead by cutting the JP1 bridge and soldering JP2.

Example use case – two signals required

One user required both signals. To accomplish this, a wire should be soldered carefully to JP2 without bridging the joint. This signal can than be used to drive a power circuit (e.g. transistor or Mosfet via a resistor, sinking or sourcing)

Location of the solder and cut bridges (bottom of PCB, hot side)
MG3’s existing circuit to source or sink a Solid State Relay (SSR)

Note: the MOSFETs are carefully chosen to avoid shorting 5V to ground during switching events.

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