The fault is mainly to poor power output part. The borne power amplifier in R, L power output circuit, respectively, set up two insurance tube. In actual inspection, the causes of the failure is more insurance burn out or tube in contact with the base found in bad repair AR4R cement resistance have burn out, other components not seen abnormal change AR4R (0.22 Ω / 7 w) and internal damage (STK401-140). Replacement of authentic power amplifier block. Commissioning is normal.KJbservice manual download site