There is a good "old" 2401 on my desk for repairing. The client described as follows : Working fine during soundcheck, suddenly channel 2 switched off in concert when seeing a "bassdrum-attack", the channel "came back" after some moments, doing the same procedure every time, the amp saw a "bigger" bass impulse. After doing some measurements I found these facts : Input : sinus-signal 1 kHz, load 8 Ohms : Channel 1 is working fine, with normal behaviour at clipping point etc. Channel 2 is working fine until clipping-point, breakdown with switching off the channel. After reducing the input signal, the channel reswitched again after some seconds. Doing the same with 10KHz both channels are working fine. Connecting the inputs to a music-signal both channels are showing the failure of channel 2 at the clipping point. All vcc's are okay , the output-boards are pretty good ( no failed E-resistors ), no heat problems, capacitors around +-15V supply on the mean-board are looking good. Anyone, who could help me to find the way out of this failure.