My preamp has bumblebee capacitors.
The issue is one side channel has huge hum.
I tried to measure with my lcr meter, and value of all capacitors are fine.
Actually, they are still almost double. (I heard it's normal for old caps since they have +80% ~ +100% tolerance is normal)
Still, I can see many cracks on the capacitors.
I know I better replace them all but my question is
can capacitor be bad even they have good capacitance value?
If so, I do I know which one is bad?
The issue is one side channel has huge hum.
I tried to measure with my lcr meter, and value of all capacitors are fine.
Actually, they are still almost double. (I heard it's normal for old caps since they have +80% ~ +100% tolerance is normal)
Still, I can see many cracks on the capacitors.
I know I better replace them all but my question is
can capacitor be bad even they have good capacitance value?
If so, I do I know which one is bad?
It’s possible. I’ve seen bad electrolyrics measure ok an an lcr meter but they will not retain a charge. If your caps are cracked then replace them all. They absorb water from the air and start leaking dc and will damage tubes.
Double is definitely not normal for paper or foil caps.
Moisture is often the reason if you measure unusually high values.
Because water has high dielectric constant around 80, which is about 20 times more than paper or foil.
I'd consider anything above +20% as highly suspect.
Moisture is also conductive and causes leakage current.
Whether this is the cause for hum in your case is another story ...
Moisture is often the reason if you measure unusually high values.
Because water has high dielectric constant around 80, which is about 20 times more than paper or foil.
I'd consider anything above +20% as highly suspect.
Moisture is also conductive and causes leakage current.
Whether this is the cause for hum in your case is another story ...
