Issue with static noise and amplifier going into protection mode

[dakota]

I’ve been experiencing a few issues with my audio setup after turning it on for the first time in about a year.

I’m using a Cambridge Audio CA 651A amplifier, and I connect it to my laptop or phone via the 3.5mm audio output.

First, I’m hearing a faint static noise from the speakers when no audio is playing. The noise increases significantly when I connect the laptop charger or touch the fingerprint sensor. The static noise is also still present when I connect my phone instead of the laptop, and it increases when I interact with the phone screen. I also hear loud popping sounds when my MacBook goes to sleep and when it wakes up.

Second, the amplifier went into protection mode (overheating light) when I started playing music. After I reconnected the cables at the back, I was able to listen to music for a couple of hours without any issues (apart from the static noise). However, the amp went into protection mode again about 10 minutes after I stopped playing audio.

Has anyone experienced something similar or have any idea what might be causing these issues?

 

[efernand1]

I’ve been experiencing a few issues with my audio setup after turning it on for the first time in about a year.

I’m using a Cambridge Audio CA 651A amplifier, and I connect it to my laptop or phone via the 3.5mm audio output.

First, I’m hearing a faint static noise from the speakers when no audio is playing. The noise increases significantly when I connect the laptop charger or touch the fingerprint sensor. The static noise is also still present when I connect my phone instead of the laptop, and it increases when I interact with the phone screen. I also hear loud popping sounds when my MacBook goes to sleep and when it wakes up.

Second, the amplifier went into protection mode (overheating light) when I started playing music. After I reconnected the cables at the back, I was able to listen to music for a couple of hours without any issues (apart from the static noise). However, the amp went into protection mode again about 10 minutes after I stopped playing audio.

Has anyone experienced something similar or have any idea what might be causing these issues?

A couple of my friends had faced something like this. Cambridge Audio are very sensitive products and often visit the repair shop for these type of issues. You may want a technician to check it

 

[dakota]

I thought it might be due to some earthing issue as the static noise increased/changed when I connected the charger, touched the screen etc.

Please let me know if you know a good technician in the Panipat/NCR region.

 

[Hari Iyer]

My Denon AVR had similar issues couple of months ago. I opened and manually checked all voltages and individually all the transistors and even added a dab of solder at critical locations to rule out any dry solder. Fortunately none of the Transistors were damaged.

Then I noticed some bunch of hair near the transistor which I manually removed. I the vacuumed and blow from my vacuum cleaner and turn on. By removing the accumulated dust over the years and removing the hair solved my problem. Then I went ahead and cleaned the mother board with isopropyl alcohol and left them over for a day and cleaned all residue. Since past 6 months of daily use, I have not faced any problem since then.

If you can open your amplifier top cover and bottom cover and try if this is the issue. Since the amplifier works intermittently I suspect it could be a servicing issue only. But YMMV.

 

[dakota]

Thank you for the suggestion. I can open the top cover and will try cleaning it. Other than that I won't be able to perform any diagnostics (don't know anything about electronics). What isopropyl alcohol did you use? I do have a 70% v/v at home but don't know if it's safe for use on electronics.

 

[Hari Iyer]

Thank you for the suggestion. I can open the top cover and will try cleaning it. Other than that I won't be able to perform any diagnostics (don't know anything about electronics). What isopropyl alcohol did you use? I do have a 70% v/v at home but don't know if it's safe for use on electronics.

If you suspect static electricity issue due to intermittent noise cleaning the track side with a layer of isopropyl alcohol and antistatic brush helps resolve the issue. It's usually an issue where very tiny tracks are too close to each other and because of the dust / hair a capacitance bridge gets developed. Cleaning them once a while removes this issue.