Grounding Laptop


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Old 11-09-17, 04:49 PM
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Grounding Laptop

Hi there...
First off, I know pretty much nothing about electricity. So that's why I'm here.

Ok, so my laptop isn't grounding, and the eletrical noise is causing humming in my microphone. Yes, I'm 100% sure this is the issue...
  • When unplugging laptop, hum goes away
  • When touching USB port, hum goes away (apparently I become the ground or something? I don't know...)
The cord going from my AC adapter to the wall is swapable, and standard. You probably know what I'm talking about, I really have no clue what it's called. Online says its called an AC power cord, but I have no clue.

Anyway, I dig enough digging online to learn that the 3rd prong on the bottom is the ground. So here's my question. If I swap out the current cord with a grounded cord, will it still work fine without killing my laptop, and will my laptop be grounded?

Thanks for putting up with my electrical stupidity.
 
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Old 11-09-17, 04:57 PM
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Subsituting a 3 prong plug power cord for the cord that came with your laptop may or may not ground your laptop. The grounding may or may not cdntinue from the brick with the power supply up the thinner cable to the laptop proper.

A separate wire from a jack shell (including the rectangular outer shell of a USB connector) or some exposed metal part connected to the laptop framework (or chassis) over to a known ground (usually a screw that holds the cover plate on a wall receptacle) will ground the laptop.
 
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Old 11-09-17, 05:16 PM
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Welcome to the forums.

If you have a power supply cube that uses a three pin A/C connector then you should already be using a 3 wire cord. Certainly wouldn't hurt to try a 3 wire cord.

You may also have a problem with your mic or wiring. I use my laptop for all kinds of audio uses with no hum. It uses a 2 wire power cord.
 
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Old 11-09-17, 05:25 PM
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Go to this site and follow the steps. It should isolate your problem and give the proper fix./ Sounds like you need "cheater plug" due to a ground loop.

How to find and fix hum in 3 easy steps | PS Audio
 
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Old 11-09-17, 05:28 PM
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I don't think that is helpful here Norm. He's plugging a microphone into a laptop computer powered with a two prong power cord. There wouldn't be a ground loop with no ground.
 
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Old 11-09-17, 05:41 PM
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Originally Posted by AllanJ View Post
Subsituting a 3 prong plug power cord for the cord that came with your laptop may or may not ground your laptop. The grounding may or may not cdntinue from the brick with the power supply up the thinner cable to the laptop proper.

A separate wire from a jack shell (including the rectangular outer shell of a USB connector) or some exposed metal part connected to the laptop framework (or chassis) over to a known ground (usually a screw that holds the cover plate on a wall receptacle) will ground the laptop.
Ok, that might work. I have to move around a lot, but that could work. Could it be any wire, or does it need to be a special one?

Originally Posted by PJmax View Post
Welcome to the forums.

If you have a power supply cube that uses a three pin A/C connector then you should already be using a 3 wire cord. Certainly wouldn't hurt to try a 3 wire cord.

You may also have a problem with your mic or wiring. I use my laptop for all kinds of audio uses with no hum. It uses a 2 wire power cord.
Thanks! I'll definitely grab a 3 wire cord and try it, if it can't do any harm. And yeah, it's a mic issue for sure, but I'm trying to find the cheap way out. It's a $2 mic I picked up from Amazon, after needing something half decent on no budget. If there isn't a reasonable cheap fix, then I'll just buy a good mic.

Originally Posted by Norm201 View Post
Go to this site and follow the steps. It should isolate your problem and give the proper fix./ Sounds like you need "cheater plug" due to a ground loop.

How to find and fix hum in 3 easy steps PS Audio
Originally Posted by PJmax View Post
I don't think that is helpful here Norm. He's plugging a microphone into a laptop computer powered with a two prong power cord. There wouldn't be a ground loop with no ground.
Thanks for the suggestion Norm, but I'm pretty sure I already tried that. I picked up an audio ground loop isolator, and when plugging the mic through it I just get static from the isolator, no sound from the mic at all.

Thanks for all the help! <3
 
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Old 11-10-17, 06:01 AM
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AllanJ's theory seems to be correct because the hum goes away when you run the laptop on battery. That means that the laptop is grounded within itself but the casing isn't grounded to the house when you connect it to the wall. The AC adapter shouldn't kill the internal ground, if that's what it's doing.
 
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Old 11-10-17, 07:29 AM
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Originally Posted by Donato_ View Post
AllanJ's theory seems to be correct because the hum goes away when you run the laptop on battery. That means that the laptop is grounded within itself but the casing isn't grounded to the house when you connect it to the wall. The AC adapter shouldn't kill the internal ground, if that's what it's doing.
Ok, that makes a little sense. So, I just need to connect some wire (copper or something) to the USB port and then to some metal in the wall?

Also, is there a reason that the case wouldn't be grounded? Just curious :P
 
 

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