The unit becomes unusually hot, shuts down, or enters protection.
Safe first checks
Turn it off and allow it to cool completely.
Make sure ventilation openings are clear and the unit is not enclosed.
Check that speaker impedance matches the manufacturer's requirement.
Do not continue using it if it overheats at low volume or with no speakers connected.
Next step
A technician should check bias, DC offset, output devices, and the power supply if the condition persists.
Bench Technician Steps
This is the model of work a qualified electronics technician follows using the exact service manual and suitable test equipment. It is not a do-it-yourself instruction to work on energized equipment.
Inspect ventilation, heatsink mounting, output devices, emitter resistors, and power-supply components for evidence of heat stress.
Using the service manual, verify bias and DC offset only with suitable instruments, correct test points, and the manufacturer’s procedure.
Do not leave a unit powered and unattended while investigating an overheating or burning-smell fault.