I have a VFD with a control board I am trying to fix. It requires an external variable resistor to be connected between the +10V terminal, analog reference terminal and ground. I found that on connecting the VR between the +10V terminal and ground, the voltage at the +10V terminal drops from 10V to around 8.78V. However, a similar board did not behave in this manner. What could possibly be the cause of this?
Many thanks in advance.