Humming noise when external monitors is plugged

[loop]

i've plugged an external monitor to my MBP and since i did it, there's a loud humming noise. if i disconnect the monitor, the noise stops.

I tried wiring the monitor base (metal chasis) to S4 ground loop, but it's not helping. It also doesn't metter in which PDU I will plug the monitor. I'm basically out of ideas.

It's obviously a bad/incompatible power supply in the monitor, but maybe there's a way to cheat it?

Any ideas?

[loop]

sorted out:

And me!

When i got my MacBook.....it had a 2 prong plug. Cut it off...and put on our local 3 prong.

There are only 2 cables.....so left the 3rd prong empty which is the Earth.

Works a charm....no buzz....."_

luckily, i had the proper 2 pin cable.

... damn, I was upset!

[photojojo]

Anytime you go cutting prongs off a plug you run the risk of damaging something if there's any kind of slight energy surge. The proper way to deal with this is a ground loop isolator.

[loop]

The local electricity network is very poor here and does not have grounding line at all. The Zero line is used for grounding, which is damn bad. I still have a surge protector in the PDU itself, so I'll be fine for a while.

I'll look for a proper ground loop isolator device. If there's no one selling them here, I'll have to import.

it's a common problem and I'm dealing with such from time to time. Will just get a few to have for whenever I need em.

Is it known if they have impact on the signal quality or not?

[photojojo]

Will the isolator affect the signal quality? I would think he better quality ones would probably be better than a cheap one, but I can't really speak to anything specific.