Teac A R650UR MK2 Amplifier Repair

Fault Left channel very distorted. Initial voltage checks on the left channel power output transistors identified the base voltages were very low less than plus / minus 2 millivolts. The R650 is modular in design and its easy to remove the main power Amplifier circuit board to carry out repair work. Once the board was removed, it became clear a repair attempt had been made previously by another engineer. R518 100 ohm had been replaced with a Half Watt resistor and the PCB track had been damaged hence one end was no longer connected in circuit. Also R516 100 ohm was discoloured but still read correct. Both resistors replaced with 1/4 Watt 1% precision resistors. The PCB track was also repaired as shown in the video. Further tests made and no other faults found. Amplifier tested and the bias for each channel set to 5 millivolts. A rather unusual fault! Amplifier working correctly.