Laptop Ground Noise... Solutions?

Hi there,
I had a very similar problem with my samsung laptop and the cause was of course the power supply.

So what i did to resolve the problem was to remove the round pin of the power supply's ac
cable, some switching power supplies generate noise on the ground pin causing this problem.

Alway be sure to orient the cable plug in the same way as if it had the round pin, the larger pin on the is also return.
(ie: ground).
ince then i have no more funny noises thru the pa system.

My 2 cents worth!
 
Wallbagner said:
Hi there,
I had a very similar problem with my samsung laptop and the cause was of course the power supply.

So what i did to resolve the problem was to remove the round pin of the power supply's ac
cable, some switching power supplies generate noise on the ground pin causing this problem.

Alway be sure to orient the cable plug in the same way as if it had the round pin, the larger pin on the is also return.
(ie: ground).
ince then i have no more funny noises thru the pa system.

My 2 cents worth!
Click to expand...

The round pin wouldn't be mains earth, would it?
Thanks for posting up to share you're experience, but I wouldn't recommend that anyone remove or break the mains earth connection on any piece of equipment.

The problem, often, is a difference in potential between mains earth and the chassis of the laptop.
That earth is there for safety in the event that your transformer fails, or whatever.

A safer remedy, keeping in mind that I'm no spark, is to manually connect the chassis of your laptop to mains earth.
Sounds dodgy, right? This is exactly what happens when you connect the line out socket to a hifi, for example.

This should have been happening for the OP since he connected his interface to a PA, but who knows if there's continuity between his laptop and interface chassis. He'd need to check.
His outputs were unbalanced too, so that's definitely not going to help.


I discovered this because I had the hum/buzz issues with an old dell laptop, but they disappeared when I used standalone rack preamps.
The shield of the cable connecting interface to preamp was creating a path to mains earth. :)

Of course, there are 101 reasons why someone might experience hums and buzzes.
I'm not saying that the above will cover all of them.
 
Wallbagner said:
Hi there,
I had a very similar problem with my samsung laptop and the cause was of course the power supply.

So what i did to resolve the problem was to remove the round pin of the power supply's ac
cable, some switching power supplies generate noise on the ground pin causing this problem.

Alway be sure to orient the cable plug in the same way as if it had the round pin, the larger pin on the is also return.
(ie: ground).
ince then i have no more funny noises thru the pa system.

My 2 cents worth!
Click to expand...

NEVER DEFEAT A POWER GROUND.

...unless you're a competent electrician doing something very temporary or live alone on an island where the only person you can kill is yourself.
 
Hi there!,
Well here'the thing!, there is a lot of confusion about the third pin on a plug and a switching power supply.
These days they come in two flavors, some have three pins for the ac mains and some only have two pins or call them prongs, one of witch is larger than the other , the larger pin or wider pin is a return.

now I'm talking about a switching power supply used for laptops and only laptops!.
The problem I was having was not hum! But rather. Whining noise! Witch was amplified by my Yamaha console and sent to my pa speakers, the noise came from my laptop thru the usb cable to my br800 to my console.
It is true that The round pin is of upmost important for all other equipment like a tube amp! Because tube amps use around 500 volts for their b+ and if not properly grounded can kill! If something goes south , but for a switching power supply adapter most come with only two pins, internally the DC output and the ac mains input are separated from each other and are used mainly for charging laptop battery's but some switching power supply's are badly designed at the filter section of the ac mains inside the power supply unit.

I am not suggesting that everybody should do what I did but the only way I could resolve the problem was to isolate the round pin of that laptop! Battery charger, like I said some battery chargers/psu's like Roland have only a keyed plug with only two pins.

I hope my message is clear.
btw, I am an experienced electronics Tecnician with over 40 year of experience, I also do electronic design.
now my solution is only for that type of problem , and no other!.

I hope you guy's understand that I would never suggest anyone to modify their equipment because of the risks involved in doing so without thinking it over or not knowing how things work!.

my 2cents worth.
 
The problem is that it takes just one reader to go right past the fine details and see only "it's okay to lift mains ground" then do it when they shouldn't.
 
cherrycobb said:
Hello,

I get the feeling this may be a regular topic so I'll keep it quick... I am using a Dell Inspiron 1545, EMU 0202 USB with a pair of active monitors. After I finally got everything connected I had not anticipated the ridiculous level of noise created by Dell's power supply. There is no noise when running on battery alone, this is fine for a time but a bit stop/start due to limited battery life...

Aside from getting a better soundcard or new computer, is there any way at all to counteract this devastating noise!?

PS - I am not prepared to remove the earth pin from the power supply as I value my life!

Thanks in advance!
Click to expand...

I have this same issue at work. A simple ground lift adaptor for the laptop ac cord eliminates the hum frequently. 5 bucks at any hardware store.
 
You must log in or register to reply here.
Back
Top