My laptop squeals when unplugged.?

1) Short (DC-Jack)

If it's a very high pitched (and very audible) whine, it sounds like a short. It might also be accomponied by a small popping sound (but possibly not)

It could be the plug is keeping the short from happening. Try to leave the adapter plugged in, but disconnect it from the wall (so it doesn't have power). Does is 'squeal' now?

Take something non-conductive (like a plastic cap on a pen) and try to gently move the DC jack (the part where the laptop adapter plugs into) back and forth -- again, gently. Does it stop or start whining when you push it a certain direction? If so, it's definitely a loose connection that is causing a short, such as the back of the DC jack could be shorting out when pushed back against a heat sink or metal frame. (If this is the problem, you should definitely consider getting it fixed ASAP, as this problem can actually start a fire or damage your laptop)

2) Short (Power Adapter)

Disconnect the power adapter from the laptop and then listen closely to the power adapter -- sure the power adapter isn't making the noise?

3) Problem with LCD, Inverter or Bulb.

If all of the above isn't the case, is it a very very very very high pitched squeel? like you can barely hear it, almost like it's up in ultrasonic? If so, try pushing the close-lid button on the laptop, does the sound stop? If so, it could be the LCD Screen, Inverter or Bulb that is having trouble operating at the lower-power setting (which would be the case when it's unplugged)

4) Speakers

Is the sound coming from the speakers? Locate the speaker holes, is it coming from there? If so, it's likely a resource problem, OS corruption, virus/spyware etc that is causing the system to lock up

5) Drive

It could also be a drive that is squeeling, but it's very unlikely that would be any different between battery / ac power and should do it pretty much either way. (such as a Hard drive or CD-ROM) If you are so inclined, you can try removing these and see if the sound still occurs. Unlikely, though. The sound here would likely be a very violent sounding whine and sudden stops, and clicks.

If none of the above seems to fit at all, try to edit your answer describing the sound as best you can, when it occurs and how you can stop it (if you can stop it).

Edit: To answer your additional details, it should not be the fan, which should operate the same regardless if plugged in or not.

That's definitely the case, right? You can stop the whine by just plugging it into power? The fans will operate differently by temperature, but if you just plug in the AC - and it stops - then it shouldn't be the fan.

The part of the laptop that you describe where the sound comes from, is that the same location you plug it in at? If so, it could still be a short.

Can you try to describe:

- How loud the sound is

- How constant the sound is

- If accompanied by another sounds

Verify that it starts - and stops - only when it's plugged into the adapter. Does it matter if that adapter is plugged into the wall?

Hope all of the above helps you narrow down on the problem (or at least exclude some of them!) As to the fan, if you access to it you could always stop the fan with a foreign object (when it's turned off) and see - briefly - if it whines when the fan isn't spinning.

Yeah, your potential furnish has a micro fan on it and the two airborne dirt and dust or warmth or the two have brought about it to slide on the spindle, you will could desire to have it replaced and the faster the extra powerful.

Have you send the equipment for check? Sometime it is normal for the machine to make some noise. But sometime it is going to be a big thing.

Please do not risk.