Noisy output when AC plugged in

Lance · Mar 21, 2008, 18:25:36

Hi all,

Just tried plugging in some speakers using the 3.5mm output jack on my laptop for the first time and there is quite a lot of white noise being put out through the speakers. To make sure it wasn't the speakers I tried some headphones and got the same. I then discovered it only happens when the laptop is plugged into the mains. Is some noise normal or should I contact HP support and complain?

Rik · Mar 21, 2008, 18:30:00

Contact HP, Lance, it sounds like there's a fault in the power supply.

Lance · Mar 21, 2008, 18:39:28

That's what I was thinking, Rik. Somewhere the power circut is causing interference

Rik · Mar 21, 2008, 18:41:13

It sounds like AC is breaking through on the DC line or it's giving off RF which is being picked up by the audio circuits - any effect on your NM?

Lance · Mar 21, 2008, 18:43:59

I've never noticed any effect on my noise margin before. This is the first time I've ever tried using external speakers or headphones and thats why I've just come accross the issue. Oh well, time to see how good the HP support is!

Rik · Mar 21, 2008, 18:46:19

Good luck.

Lance · Mar 21, 2008, 19:01:58

Thanks. The email has been sent so now it's a case of wait and see!

Rik · Mar 21, 2008, 19:02:32

HP have always been very good to me, hope you find the same.

Lance · Mar 21, 2008, 19:04:51

Hopefully - I've seen plenty of good said about their support. It was one of the things which made me look at them in the first place (other than the massive discount I got!).

Lance · Mar 21, 2008, 20:30:10

Just had the automated response come through...

Quote
We are dedicated to providing quality responses to our customers in a timely manner. All messages are handled in the order received, most are responded to within one hour.

If it is within one hour, I will be impressed!

Rik · Mar 22, 2008, 08:52:58

Me too.

Lance · Mar 22, 2008, 11:17:37

Well I got a reply at 12:03am this morning, still not a bad response time. The suggestion was to install the latest BIOS which I've now done but (not surprisingly) the problem still exists. They said if that is the case then I 'need to arrange the grounding for the notebook'. Any ideas what this is on about?

I've replied saying the problem still exists so now its a case of waiting to see what they suggest next.

Rik · Mar 22, 2008, 11:23:29

I assume they're saying that the audio in unbalanced and, as such, needs to ground (this would happen automatically in a desktop machine). How you arrange it in a notebook is going to be interesting though.

Lance · Mar 22, 2008, 16:02:32

The latest response

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Lance, grounding of the notebook means placing it on a flat surface with proper ventilation
so that it minimizes the notebook temperature. Or else place it on a thick flat wooden table/block. Wood absorbs certain amount of heat and minimizes the notebook temperature.

Love it! I'm using it on a wooden desk and it certainly isn't getting hot.

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Static noise is created by the electric field radiated by a voltage source when coupled capacitively into the instrumentation circuit. The sound card is integrated on the mother board and due to this static noise is created.

And in English this means? (I think it is saying that because the sound card is integrated its causing the issue).

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I suggest performing the following steps to isolate the issue:
Turn the wave input(under Volume control panel) to just under 50%, and the Volume to 60%, this will reduce the static noise.

It seems they haven't updated the script for Vista, as in Vista you have a per application sound mixer, not by type (ie wave, line in etc).

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* If issue persist, the issue at hand is related to hardware and needs an onsite diagnosis by HP Service Technician. I have verified our database and found out that the notebook is covered under warranty. Hence, the notebook can be repaired free of cost.

Contact details are mentioned below:

Looks like a phone call is to be made!

Rik · Mar 22, 2008, 16:10:09

Grounding involves placing it on a wooden desk. That's a new one to me!!

QuoteAnd in English this means? (I think it is saying that because the sound card is integrated its causing the issue).

It seems to be saying the sound card is vulnerable to noise pickup from a nearby circuit such as a poorly designed PSU.

Steve · Mar 22, 2008, 17:13:08

Perhaps every laptop should be supplied with a plank of wood attached to the base, Then at least ones "grounding" would be portable. I doubt a table or work bench would fit in ones' bag. It could catch on, imagine the daily commuter with laptop, newspaper and a plank of wood. Perhaps in first class the plank of wood be included with free drinks etc.

Lance · Mar 22, 2008, 17:21:07