This is a very cool looking Sony amplifier from the early 70s making it around 50 years old. How much modern electronics will last that long!
The problem was the left speaker channel was ‘popping’. Looking at the output with a scope showed the output swinging between the power rail and ground.
This is a symptom of a transistor randomly switching on and off. The tricky bit is finding out which one which can be tricky as the transistors in an amplifier are all sort of connected together.
The culprit was located and replaced with a suitable equivalent modern one as all the transistors in this amp are obsolete.
The sliders needed a good clean as they were causing the audio to be really crackly when they were moved.
Considering its age it appeared to be in remarkably good condition and happily drove the outputs into clipping. It’s only 11 watts per channel but sounded louder than I expected it to!
If you need any hifi repaired please contact me for a quote.
Email Me: orangevalleysystems@gmail.com