Laptop annoyingly humming.

[peterp]

My good old laptop has gone nuts, at least in the audio output.

I run the audio out jack into my powered monitors and recently it has started to hum/buzz really loudly when that is connected.

Someone suggested the power supply may be the source, they are right. if I unplug it the hum is gone, but Liff on the battery is short.
I have tried alternate power adapters for the Toshiba 19V 3.8amp that came with it and they all seem to do the same thing now.

Not sure how to go about fixing it, as being a laptop there is not much you can do inside it.

[Oldrottenhead]

i think you need a ground loop isolator. but getting a new battery would probably be the best solution.

[peterp]

Replacing the battery would get rid of the hum that seems to come from the power adapter ?

[peterp]

Well is that not special
3.5 mm/1/8-Inch Stereo Audio Ground Loop Isolator by Pyle

is 10$ from Amazon US
and 36$ from Amazon Canada, the Canadian version must be MUCH better.

[64Guitars]

Since you said that you get the hum with other power adapters too, it would seem that the power adapter itself is not the problem. It probably always hummed but the audio signal path was shielded and grounded well enough to block the hum. So what's probably changed is that the shielding or grounding has failed at some point in the signal path. Perhaps a bad solder joint. You don't get the hum with the battery because it's DC, so there's no hum for the signal path to pick up.

I would start by checking the cable that runs from the computer to the monitors. Perhaps the shield is damaged or disconnected at one end. Try a different cable if you have one.

If that doesn't solve it, you might have to open up the laptop case and look for bad connections. Start with the audio out jack.

You could also try moving the AC adapter around all sides of the laptop and across the bottom while it's connected and humming to see if the hum gets louder in one particular area. That might be a clue as to where the bad connection is.

It's also possible that the bad connection is in the monitors, though less likely. You could try moving the AC adapter nearer to the monitors to see if the hum increases.

You might also find that moving the AC adapter sufficiently far from the laptop and monitors might reduce the hum to an acceptable level. Perhaps you could even try to shield the AC adapter by putting it in a metal box of some sort and keeping it as far from the laptop and monitors as possible.

It's probably a bad cable from the computer to the monitors or a bad output jack in the laptop. They get a fair bit of handling so they're more prone to failure than something inside the laptop. But it's possible. Solder joints can detach with age, especially if they weren't good solder joints in the first place.

[peterp]

Tried many combinations of wires, plugging into my mixer instead of the monitors and moving things around nothing helped.
The HUM continues.

I did try another laptop and that did not produce the hum, so guessing surgery may be needed to look for bad connections inside mine.

Oddly someone suggested plugging into a different power outlet in another room with a long extension cord, and that also cleared the hum. No idea why, but problem is most likely inside my laptop itself.

[AndyR]

I had the same problem - power-supply on the laptop got into an earth-loop problem with the power-supply on my powered monitors coming out of my mixing desk. I could only have one or the other on. Even if the speakers were turned down, or the send to them muted, horrid hum on any track.

Apparently, and this was a few years back, it was a common problem with laptop power-supplies in home-recording setups. Whether it's a problem with the power-supplies themselves or in how the laptop takes it, I don't know. From your experience (it's just started happening, and other power-supplies do it now as well), I suspect it's the way that the laptop is taking the power... It has just started happening hasn't it? It's not like it was for me, is it? - these particular power monitors got added, and the mains set-up changed, and the hum started for me then.

I never bothered getting an earth-loopy-thingy, I understand this would have worked, though. I just turned off the laptop power-supply when I needed the monitors on (I'm in headphones most of the time anyway).

It all got solved quite quickly when I moved to an MBR instead using a DAW on the laptop!!

[peterp]

Yes, I've had the monitors for a few years now, and the laptop for almost a year.
All was working fine till last week.

I'll get a large bottle of scotch, a screw driver and a soldering iron and have a go at it when I get off the on-call duty next week.
I did notice the power jack on the laptop side seems to be very loose almost falling in, suspect something might not be quite right in there.

[IanR]

It may a process of elimination - Make sure there are no loose connections to anything else plugged into your laptop.  If you are plugged into a powerboard, turn off everything else connected to it to see if that helps.  If it still hums, try plugging into another wall socket on another power circuit inside your house.

I once had a hum coming from my pc and found that it was the video cable causing interference. With laptops, it can also be an improperly matched power supply.  They sometimes have a lead into the transformer and a lead out as well, so there are two points of possible failure.

Although, reading through the posts above again, it sounds like there is some other gadget (fridge, microwave, TV, etc) plugged into your house's electric circuit causing interference.  Try turning off everything one-by-one and see if you can isolate which one it is.

Ian

[peterp]

Seems the culprit was the power in jack.
Found it was more broken off and wires fraying/breaking than just loose as I thought it was.
Re-soldered the wire ends and epoxied the plastic housing back to where it looks like it should have been.
Hum is mostly gone, can still hear it faintly in the background but that may have always been there and I did not notice it. With the volume turned up it cannot be heard.

So laptop is back to working order, now I just need to get the fish paste out of my BR-800 7/8 fader.