Hi every one,
My ML-9 have a noise (like a hum with crackles) that I can hear in speakers, both channels.
I know it's 100Hz, not very loud.
Inside the box there is noise but seems to be normal I guess.
Nothing is vibrating.
From where should I start ?
Any clue is most welcome.
Thank's
Lars
My ML-9 have a noise (like a hum with crackles) that I can hear in speakers, both channels.
I know it's 100Hz, not very loud.
Inside the box there is noise but seems to be normal I guess.
Nothing is vibrating.
From where should I start ?
Any clue is most welcome.
Thank's
Lars
Crackling can have many causes the first being mains induced external noise .
Inside the amplifier which I take to be a non stabilized power supply (ML-9) it could be the large power supply capacitors breaking down , a bad soldered connection , a resistor breakdown /overheating .
With the hum also I would check out the whole power supply as you are not alone in having this fault in the ML-9 , one poster replaced the capacitors.
Look for overheating , as the transformer is encapsulated its less likely to be radiated interference .
Inside the amplifier which I take to be a non stabilized power supply (ML-9) it could be the large power supply capacitors breaking down , a bad soldered connection , a resistor breakdown /overheating .
With the hum also I would check out the whole power supply as you are not alone in having this fault in the ML-9 , one poster replaced the capacitors.
Look for overheating , as the transformer is encapsulated its less likely to be radiated interference .
The NAD 7020 is a stereo receiver so the question is does the noise occur only on the use of the amplifier section or receiver section ----or both ?
Thank you Duncan2,
I'll mesure all the caps of the power supply and the 2 big 36000 first.
The noise is on both channels without music.
I'll mesure all the caps of the power supply and the 2 big 36000 first.
The noise is on both channels without music.
ML-9 has one transformer in center and 2 amplifier boards at both sides. That means both channel share the same power rail. This setup is very easy to get ground loop and hum. One of my DIY amplifier has similar arrangement, and I ended up using two transformers to solve this problem.