Since IC2301 by touching method step by step forward after by touching the audio signal input on foot, speakers are "kaka" sound; When touching Q2105b extremely, "kaka" sound, using a multimeter to measure the tube voltage each foot, its great 12 V c, b is 2.8 V, e is 0 V, Q2105 damage. With the same pipe commissioning, troubleshooting.kBDservice manual download site