I recently bought 2 receivers to play with (fix or break – whatever the fates have in store): a Yamaha CR-240 and a Sansui 6060.
I have cleaned up the controls so they work quietly.
They both have some noticeable hiss – the Sansui is much more noticeable. At first I had naively thought I could replace some capacitors to take care of this. Then I searched this forum and found that resolving hiss may be more complicated.
The hiss in the Sansui starts at ¼ turn of the volume knob and remains constant at higher volumes. The hiss in the Yamaha is proportional to volume.
I have an oscilloscope and a VOM, but I am a novice at this (1 college general electronics course long ago).
At any rate, I have some questions:
1. As I trace the circuits (live), what should I be looking for on the oscilloscope, as far as hiss goes?
2. As a variation of #1, when I probe a capacitor in the circuit, what should I be looking for to differentiate good capacitor from bad?
3. I have looked for visible evidence of blown capacitors. The larger ones sit in puddles of hard goop, which I originally thought were leaked electrolyte. After more study, I suspect this is in fact adhesive. Were larger electrolytic capacitors commonly glued to the boards?
Thanks.
I have cleaned up the controls so they work quietly.
They both have some noticeable hiss – the Sansui is much more noticeable. At first I had naively thought I could replace some capacitors to take care of this. Then I searched this forum and found that resolving hiss may be more complicated.
The hiss in the Sansui starts at ¼ turn of the volume knob and remains constant at higher volumes. The hiss in the Yamaha is proportional to volume.
I have an oscilloscope and a VOM, but I am a novice at this (1 college general electronics course long ago).
At any rate, I have some questions:
1. As I trace the circuits (live), what should I be looking for on the oscilloscope, as far as hiss goes?
2. As a variation of #1, when I probe a capacitor in the circuit, what should I be looking for to differentiate good capacitor from bad?
3. I have looked for visible evidence of blown capacitors. The larger ones sit in puddles of hard goop, which I originally thought were leaked electrolyte. After more study, I suspect this is in fact adhesive. Were larger electrolytic capacitors commonly glued to the boards?
Thanks.