Thanks.I wonder if their is some form of constant current going on with that controller, and when you remove the LEDs that messes things up. Have you tried still leaving in the LEDs on the controller and wiring your potential divider to the LED's cathodes?
But would that work?
The LED would not be able to light up then?
Who knows? We are dealing with an unknown box of electronics so depending what is inside it the answer is yes or no.Again it depends what is in the box.