Mindsensors’ Motor Mux Power Input Modifications

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For ease of use I have modified my Mindsensors' NXT & RCX Motor Multiplexers with the following Power Supply Modifications. This method finishes the issues associated with the external power supply leads fraying, braking and in the case of the RCX Motor Mux, shorting to the PCB Components on occasions. Which is not at all advisable!

I used of standard type D.C. plug & sockets for the external Power Supply for Motor Mux's instead of the original Terminal Blocks. I actually haven't replaced the Terminal Block with a D.C. Socket, but I used the heaviest copper wire that fitted into the original terminal block. I soldered this wire to the D.C. socket & terminated it as close as possible to the existing Terminal Block so the base of the socket rested on the PCB. Extra support is then supplied by some trusty Hot-melt Glue. You could also use epoxy resin if you wish, but they hot melt glue is a little easier to remove if needed in the future.

NXTMMX-Nx Motor Mux
Mindsensors' NXTMMX-Nx Motor Mux Modifications

I also inserted a 1N4004 diode in series with the positive cable of the D.C. Cable, hidden inside the D.C. Plug to avoid polarity issues when used with various types Lego Battery Boxes.

This method of supplying external D.C. supply is a real lifesaver when for some reason the battery box heads in the opposite direction to the Mux and is also good for young hands. If you use a new style "Power Functions" Battery Box, you can negate the diode as polarity won't be an issue.

MTRMX-Nx Motor Mux
Mindsensors' MTRMX-Nx Motor Mux Modifications

I've deliberately used the same size D.C. Plug and Socket as used with the NXT 7.4v Lithium Polymer Battery, as I can also us my regulated 9v Bench Supply or the 10v D.C. Plug-pack Charger. I intend to purchase a 9.6v Lithium Polymer Battery & charger, as used in model aircraft to replace the heavy rechargeable AA batteries I normally use with the Mux's. This will reduce the battery weight by more than half which is always an advantage!

There is also no reason why the same modifications can't be applied to the Mindsensors' 8 Channel Servo Controller for NXT (NXTServo-v2) as well. Although a different sized D.C. plug & socket is advisable due to the difference in supply voltage. 6 volts is required for the NXTServo-v2, instead of the standard 9-7.2 volts for the other Muxes.

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