OK, so the connector in the first piccy is wired the same as mine
Red = +5V
Yellow = ground
Black = data
That said, the pictures you show are for the RA motor card???
You started the thread saying it was DEC that was playing up????
Either way, to test the board, you need voltage mode on your meter and
you measure with meter ground to YELLOW and meter red to RED
When detecting the sensor, this should show +5V, then it switches off.
BLACK is always held up at +5V by a weak pull up resistor so will always be at +5V
unless the sensor is energised and the magnet trips it.
i'm thinking ordering a new correct part and try a redo. Just want to make sure which color wire to put on which pin.
Have added a markup of the spec sheet for the alternate Allegro chip i noted above.
I marked the pins with the wire colours that match your board connector functions/colours.
You can see its colours/functions line up with those coming out from under the worm in my piccy
Soooo, thats the way to wire it up :-)
Andrew Johansen Melbourne Australia