This page discusses a number of issues that had to be repaired in Beomaster 6000 units that came across beolover's work bench.
Overheating and Failed Output Transistors
The quiescent current in the output amplifiers of the Beomaster 6000 is adjusted by trimmers that are usually corroded after 30 years. They can go open circuit or settle at a higher resistance due to minor vibrations or temperature related stresses. If this happens the output transistors can burn out or get partially damaged.
Volume Drive Failure
The Beomaster 6000 uses a motor driven volume potentiometer to achieve remote control and button based volume control. This motor connects to the potentiometer via a rubber belt, which typically rots away. This belt can be replaced.
Refurbishing of the LED Displays
The Beomaster 6000 uses similar seven segment LED displays like the Beomaster 8000. They also often have missing segments after about 30 years in service. Luckily, these displays can be fixed with surface mount LEDs.
Recapping the Power Supply
If solid longterm performance is desired it is recommended to replace the electrolytic capacitors in the power supply. Due to the relatively high temperature in the power supply section, these capacitors tend to expire earlier than those on the other boards.