Inspiron connected to stereo installation gives bad sound while charging

Dynthe,

Some of the Dell notebook computers can experience a Ground Loop noise under certain circumstances. This is mainly an issue on the older models. If you have this problem on a new model then the adapter might be faulty. Below is the information about the problem as it pertains to older models.

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Symptoms Include:
1.  A scratchy, staticy noise when moving the cursor, and
2. The noises occur only when the computer is plugged into its power adapter and not running on battery power, and
3. The noises occur only when the computer's output jack is connected to another device (like a mixer, power amp, etc) that is also plugged into a/c current with a grounded plug (3 prongs).

If you have similar noises but under different circumstances then it is not this Ground Loop noise.


To Diagnose:

1. Disconnect the power cord from the computer and run on battery power, or

2. Eliminate the ground either on the computer or on the other device it is connected to, by using a 3 prong to 2 prong adapter available at hardware stores. Use this adapter just as a temporary diagnostic tool because eliminating the ground can be potentially dangerous and could cause your warranty to become invalid.

In either case if the noise stops then it is the Ground Loop. It is caused by the design of the notebook's power adapter and there is no repair or replacement that can fix it, but there are some workaround solutions.


Solutions:

1. Isolate the grounds from each other by using a ground isolator. Several forum members have given us positive reports on Radio Shack's $16 Ground Loop Isolator (270-054). There are other such devices available for more money which would probably be better for someone doing pro audio work.

2. Or use non-conducting material to connect the 2 devices; specifically by using optical spdif (Toslink) to transfer the audio signal rather than copper cables. This is not as practical as the 1st solution because the notebook computers don't have an optical spdif port, so this would require getting an external soundcard that has optical spdif output, and a receiving device that has an optical spdif input port.

An external sound card is not in itself a solution, because you will still get the Ground Loop if you use its regular metal jacks to make connections, if the other circumstances described under 'Symptoms' are also present.

Hi Jim

Thanks for your usefull answer. It's a brand new Inspiron 1545 and I don't here noises when moving the cursor. After looking around, I found several similar cases on the internet. Indeed, it seems to be caused by the ground loop. They all give the same solution, which is eliminating the ground.

You say this would only be a temporary solution, but what exactly is the danger? What could happen if I do this?

I'm not doing pro audio work, just want some music in my house, so I'm not willing to spend a lot of money on this. Maybe I'll look for the ground loop isolator but I heard this doesn't do any good to the sound quality. But would that be noticable when just playing in my livingroom?

Thanks in advance!

Regards, Dynthe

Because Dell had changed the design of the adapters that caused the ground loop with the old laptops, I would advise that you get in touch with tech support because your adapter might be faulty and need replacing. If a replacement does not cure the problem then you might want to try the methods mentioned.

I don't know If your power adapter's plug  has three prongs on it or only two. If two, then the 3 to 2 prong plug adapter won't make any useful difference.

The main danger in using a 3 to 2 prong adapter is that it defeats the ground prong, which is a safety device that helps to prevent electric shock in the event of a short in the wiring. Other than that it can void warranties. If it works at all then it shouldn't matter whether you use it on the computer or the stereo, so if one of them is out of warranty pick that one. But forum members have reported good results with the Radio Shack device and it used to be cheap. I don't know what it costs now.

Hi,

I've contacted the Dell support centre through e-mail and mentioned the problem. I'm now waiting for an answer. Hopefully they replace my adapter and will my problem be solved.

My adapter's plug had three prongs. Alltough, my stereo plug has only two. So maybe a 3 to 2 prong plug adapter won't be the solution after all. Also, I'm not really willing to take the risk of an electric shock :-).

I've found some kind of device similar to the Radio Shack's one, that I can order in Belgium (where I live) for about 8 € so if I don't get an adapter replacement from Dell I'll consider ordering that. I'll post as soon as I got an answer from Dell because it may be usefull to future users with the same problem.

Thank you for your help!