If it's anything like a few I have in the shop here, It a selector / preamp IC that routes the input signals to the amps thats gone buhbye
CLIP: red, to the left of each Gain control.
Normal indication: illuminates whenever the amplifier is driven beyond full power. The LED's brightness indicates the amount of distortion. Distortion that causes only brief flashing may not be audible.
During muting, the indicator fully illuminates. This occurs during normal "On-Off" muting.
•Bright red illumination while the amp is being used indicates either thermal muting or a shorted output.
•If the amplifier overheats, the fan will run at full speed, and operation should resume within one minute. Allow the fan to run, and make sure the amplifier ventilation is adequate.
•A shorted or overloaded output circuit will cause excessive Clip flashing and possible overheating.
•If distortion is audible without a Clip indication, the problem is either before or after the amplifier. Check for damaged speakers or overloaded signal source. The amplifier Gain control should be in the upper half of its range to prevent input overload.
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