For the B205D a common problem is either of the 15 volt regulator that are common TO220 three lead devices... Hint: They are a PAIN to change due to packaging. One has to be careful to replace the heat sink compound on the main amp chip as well.
This repair is NOT for the inexperienced person. The amp and power supply attach to the back plate and the short leads from the preamp don't help in the repair.

Bad audio chip.