CASE # 197856. JANUARY 21, 2026 . SANSUI AU-517 AMPLIFIER. CRACKLING, POPPING SOUND IN LEFT CHANNEL.
Nice amplifier. Build to last long time. Ventilation , sectional construction , not overloaded schematic, good protection circuit , shielded boards by metal covers ., good components management on boards ( no electrolytic capacitors close to heat-emitting components.
Classic case for troubleshooting to the component level. No nonsense, massive components change. Cleaning front controls and boards, dusting, testing voltages from the power supply, vibration test, soldering joints refreshment. Capacitors ESR test – bad replaced. ( not many found out of parameters) . PROBLEM IS STILL THERE. Focused on the left channel output board. After applying heat to small signal transistors in working mode, crackling starts intensify ( 1 -3 seconds touch soldering gun to the plastic body of transistor ) . BINGO. Replaced 2 small transistors 2SA750 – problem solved. Tested DC offset voltage on both channels – ok.
