STEP 1. Check if the error message is displayed on the multivision display.
STEP 2. Check the service data for multivision display.
STEP 3. Check the microphone for multivision display.
STEP 4. Replace the microphone unit temporarily, and check the trouble symptom.
STEP 5. Check of short to power supply, short to ground and open circuit in SNSE, MIC+ and MIC- line between microphone unit connector and multivision display connector.
STEP 6. Retest the system.