Remedy
1. Check the HMI for display and remove the HMI and the test voltage to the HMI.
2. Check the white HMI plug on far right of the PCB (low voltage connection).
3. If using the Key: Check the Key connections (black, white, red, green) are plugged in to the correct position on the PCB. (Next to orange BUS connection leaving one space.) Check the pins on the plug.
4. Check the bridging links are in LR & 230 V out.
5. Replace the board.
6. Occasionally the Key connection (green flap) can cause this.
7. Check the 230 V external wiring does not run alongside the BUS connections.