Beomaster 8000 Repair: Output Stages

Beomaster 8000: Exchange of main output transistors.

Failing corroded quiescent current trimmers in the output amplifiers of the right and left channels often lead to a runaway current situation which destroys the power transistors that provide the output current. An easy test of the transistors is to measure the resistance between collector and emitter. If it is close to zero, the transistor is burned through. If this occurs these transistors need to be replaced, which involves the removal of the heat sinks. The procedure is a relatively tedious process since the transistors need to be slid into the heat sink from the side while making sure that the mica insulation sheets are in their correct place and covered with heat transfer compound. 
Please, visit these blog entries at http://beolover.blogspot.com for detailed accounts of this restoration procedure:

• http://beolover.blogspot.com/2013/09/beomaster-8000-output-transistor.html
  
• These two posts reports a case, where only one transistor died in the right output:
  
• http://beolover.blogspot.com/2014/02/beomaster-8000-interesting-output.html
  
• http://beolover.blogspot.com/2014/03/beomaster-8000-right-output-working.html
  

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