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Working fine but now nothing.

Posted: Fri May 29, 2015 9:38 am
by seven_au
I purchased this motorshield just a few weeks ago and have been running it on top of an Eleven board using two 6-12V motors with a 9V battery pack (6x1.5V). It was working just fine until today.
I thought that the voltage may have been dropping to under 8 volts so I connected it up to two 6v battery packs in a series - registering 10.5V on a multimeter, but still nothing.
I am using the standard Freetronics "HBridge shield demonstration" code.
There is zero volts registering on each of the motor channels when measured at the motor output terminals.
I use this with my Programming class (secondary school) so it is possible that one of my students made a fatal mistake.
Does anyone know a way that I can test the shield to see if it is still alive?

Re: Working fine but now nothing.

Posted: Fri May 29, 2015 12:08 pm
by andrew
seven_au wrote: I use this with my Programming class (secondary school) so it is possible that one of my students made a fatal mistake.
Does anyone know a way that I can test the shield to see if it is still alive?
Afraid if the shield is setup with a configuration that is known to work for you, and no longer does then it would have suffered a catastrophic failure in the hands of others.

A final test could be to plug the host board into a 9~12V DC adaptor, fit the "Bridge VIN To Motor Power" jumper, and run the demo sketch. If nothing is measured at the motor terminals then the controller ICs are dead.

Re: Working fine but now nothing.

Posted: Fri May 29, 2015 12:48 pm
by seven_au
Thanks for the quick reply johnb,
I will get myself a 12V adaptor tomorrow and try it.
Do you know what the most likely cause of this might have been? - just so I can try to ensure that they don't do it again.
I am pretty sure that they would have hooked up the polarities correctly, but I can't ensure that they didn't stick fingers, screwdrivers, or multimeter leads anywhere near the ICs.

Re: Working fine but now nothing.

Posted: Sat May 30, 2015 6:29 am
by andrew
seven_au wrote:Thanks for the quick reply johnb,
I will get myself a 12V adaptor tomorrow and try it.
Do you know what the most likely cause of this might have been? - just so I can try to ensure that they don't do it again.
I am pretty sure that they would have hooked up the polarities correctly, but I can't ensure that they didn't stick fingers, screwdrivers, or multimeter leads anywhere near the ICs.
Students - anything is possible. Now and again I teach classes, and some children will do something backwards after being told not to do something ... "just to see what happens...".