Let's Make Robots!

Magic blue smoke

As part of a mixed set of robot parts I bought on ebay I received this Dagu 4-Channel Motor Controller. On the back there was a trace broken so I soldered in a wire to replace it and hooked it up to the Rover5 (from the same set). Wired it to an Arduino UNO and programmed it to run a motor test. Applying power to the board, before the Arduino had even started PWM, one of the driver ICs began smoking.

Here IC U8 can be seen glowing red hot and emitting magic blue smoke.

Now the magic blue smoke is out I'll never get it back in. Still tinkering with the board to see if any of the other motor drivers / channels work, perhaps I can use the board for something else (2 motor robot for example). I'll be scouring the web for another board for my Rover 5.

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OddBot's picture

Nice "caught in the act" photo. You say the Arduino was not PWM the board yet. Does this mean the pin was still set to input (the default state) and thus open circuit?

The blue boards are first generation boards and were prone to do this with battery voltages over 7.5V.

We have modified the boards since then and sold 100's of them without any more complaints.

markcra's picture

If I recall correctly the pins (PWM & Dir) were all set as outputs however there was sufficient delay that no PWM was set on any pin while the IC was toasting itself.

I have a second blue board running perfectly *touch wood* in SPANR and I received this board in an already damaged state so no major loss. Will be buying another board for the Rover 5 base when I get around to it.

RobotFreak's picture

Welcome to the club, markcra. Same happened to me using this controller. No idea why. But the photo looks great.