Shock from 2010 MBP and guitar.

[conanthewarrior]

Hi everyone, I have a strange problem.

My MBP is fine when used alone, but If I am reading tabs online and playing my electric guitar, if I touch the case of the mac, and my guitar strings, I get a shock.

It is not a big shock, but it is enough to know it is there, and if I keep my hand on it it is constant, not a sharp quick jolt, but continuos.

As you can guess, this gets quite annoying when I am trying to learn a song constantly having a tingle go through my arms.

Any ideas what I can do? I've also posted on a guitar forum, and got some help there, and it appears that my guitar is correctly wired.

Any help would be much appreciated, Conan.


EDIT: I just saw another thread that reminded me of something, I am using a non apple magsafe charger, if that makes a difference.

 

[uller6]

Sounds like a ground loop problem: your ground level voltage on the guitar strings (grounded) is different from the ground level voltage on the case of your MBP (also grounded). The same thing used to happen to me on my old powerbook when I played. In my case, the issue was a broken ground pin on my amp's power cord.

Make sure you're using the 3 prong grounded extension cord on your power adaptor - if you use the 2 prong connector your laptop won't be correctly grounded and you may have this issue. Also try plugging the laptop into the same power strip as the amp (in case you have ground level shifts between different outlets in your house). Or, as you say the issue could just be that you're using an off-brand power adaptor.

Good luck!

 

[conanthewarrior]

Sounds like a ground loop problem: your ground level voltage on the guitar strings (grounded) is different from the ground level voltage on the case of your MBP (also grounded). The same thing used to happen to me on my old powerbook when I played. In my case, the issue was a broken ground pin on my amp's power cord.

Make sure you're using the 3 prong grounded extension cord on your power adaptor - if you use the 2 prong connector your laptop won't be correctly grounded and you may have this issue. Also try plugging the laptop into the same power strip as the amp (in case you have ground level shifts between different outlets in your house). Or, as you say the issue could just be that you're using an off-brand power adaptor.

Good luck!

Im in the UK, so all plugs are 3 pronged. The ground prong on the third party adapter is plastic though, so I guess it doesn't work.

Is this dangerous? If it is I guess I will have to get a different power adapter.

 

[Fishrrman]

[[ Is this dangerous? ]]

It could be VERY dangerous, if there's a problem with the house wiring.

At the very least, get a power strip, preferably with a grounded plug, and plug both the computer AND the guitar amp into the SAME power strip.

 

[snaky69]

Im in the UK, so all plugs are 3 pronged. The ground prong on the third party adapter is plastic though, so I guess it doesn't work.

Is this dangerous? If it is I guess I will have to get a different power adapter.

The third prong being plastic means your MBP isn't grounded at all. I'm always weary of using non-grounded AC adapters for expensive electronic equipement, but that's just me.

Perhaps you could borrow a genuine AC adapter from a friend and see if the problem goes away?

 

[conanthewarrior]

To be honest everyone else I know uses PC's, so I unfortunately can't borrow a charger. The power strip sounds like a good idea, as I think our house wiring could be bad, lightbulbs always explode and the powers always tripping.

Should I get a standard one, or one of the more expensive ones with say a surge protector or something?

 

[jerirat]

Get a power strip with a surge protection!! And please get your house wiring fixed. Exploding lightbulbs is not good.

I'm getting ready to install a whole house surge protecter but I will still use individual surge protecters on all my computers and home entertainment equipment.

 

[BigBuns]

I think our house wiring could be bad, lightbulbs always explode and the powers always tripping

Yikes... Sounds like the grounding problem from your third party apple adapter is the least of your electrical worries.

And yes I would also recommend getting a surge protector to connect both plugs into so they are grounded together... and then maybe get an electrician to check into those exploding lightbulbs

 

[burgman]

To be honest everyone else I know uses PC's, so I unfortunately can't borrow a charger. The power strip sounds like a good idea, as I think our house wiring could be bad, lightbulbs always explode and the powers always tripping.

Should I get a standard one, or one of the more expensive ones with say a surge protector or something?

Google about musicians and electrocution then decide if an Internet forum is your best plan to save your life.