Don't know if this helps, but the SR-63 and SR-82 had this problem resulting
from a small capacitor bad in the power supply area. Can't quite remember
the value - I think it was 2.2 uF. It was a small yellow electrolytic.
It was used to lightly filter a dc line, then this reference was used for
the sharp cut-off function at power-off.
When the machine is turned off, it cuts off the speaker relay quicker this
way. With the bad cap, the protection just stays engaged.
Mark Z.
