SMC05A - How To Tell If the Driver Is Blown

Support Motor controllers/drivers and motors
1

I have built a system with an SMC05A, and based on correct feedback (blinking green LEDs) have correctly programming it to run dual motor (I have it connected to a Tamiya 70168 double gearbox as that’s a recommended combo on the web site.)

I have written a program which ramps each motor speed up and down as a test, and the LEDs for each motor turn on in succession as expected (green for forward, red for reverse.) I have placed a 0.1 uF ceramic capacitor across each motor as advised, then connected the motors (with a 9-Pin D-Shell Connector for quick disconnect). The LEDs continue to perform as expected, but the motors do not give any indication of life.

Is there a single electronic test that can give an indication whether or not the drivers are blown. (I have tried to be careful, but I am a novice may have made a boo boo.) I have access to a logic analyzer, a meter and in a pinch I have a friend with a scope.

Possibly relevant info: So far I have not tried to run the motors faster than 1/4 of maximum speed (32 out of 127). I have 4x AA batteries connected to the motor power input, and input voltage is about 6.4V.

2

Hi.

If the LEDs on the driver are working but the motor outputs are not, the driver is probably damaged. Have you tried looking at the outputs with a multimeter?

You mentioned that you were only running the motors up to 1/4 of their max speed, which corresponds a motor voltage of about 1.6V. That voltage might be too low to get the motors to move. Could you try running the motors at a higher speed?

-Claire

3

I tried running the motors at full speed and I’m getting nothing.

I put a resistive load across the outputs from the driver board at the suggestion of an EE friend of mine and measured zero volts. I assume I somehow blew the drivers, so I’ve ordered a replacement.

Thanks for your help.