Yamaha XM4220 Owner's Manual - Page 12

Troubleshooting The following table lists the main causes of abnormal operation and the corrective measures required as well as the protective circuit operation in each case. Indicator Possible Cause Remedy CLIP indicator lights up There is a short at the amplifier's speaker outputs, the speaker's inputs, or in the wiring. The impedance of the connected speaker is too low. Locate and remove the short. Use a speaker with a minimum impedance of 4Ω (8Ω in Bridge mode). PROTECTION indicator lights up The heat sink temperature has exceeded 90°C. A DC voltage of ±2 V or greater was detected in the amplifier's output circuit. Check the ventilation around the amplifier and improve the airflow if necessary. Consult your dealer or a Yamaha service center. Protection Circuit The PC limiter circuit activates to protect the power transistors. The thermal protection circuit activates to protect the power transistors. The output relay activates to protect the speaker system. 12