25d-Encoder problems

I recently purchased x2 25d motors from Pololu. Upon some initial bench testing, I believe there is a problem with both of the encoders.

I wired the motors as indicated from the datasheet, applying 12V power to Red, GND to black, 5V to blue, and GND to green, using variable DC power supplies. I’ve connected an oscilloscope to the encoder channels and have found that:
-1 of the motors sees a constant ~5V on channel B with the motor spinning while channel A is constant 0V
-The other motor doesn’t see any voltage on either channel, and shows constant 0V on both.

Did I receive bad encoders? Is there a way to test to be sure?



We test every unit, so seems unlikely for you to have received two bad encoders in the same order. Can you post some pictures of your setup that show all of your connections, including where you are probing with your scope?

- Patrick