Faulty Power Brick, or just Cheap?

I regularly plug my laptop into my home theater receiver so I can play music..I use a standard mini-jack to stereo RCA (red/white) and plug it in directly. I've always done this on battery, not purposefully, unplugged from the charger.

Well last night the battery was low so I plugged it in. Immediately the speakers started to loudly hiss bad feedback and noise. The same kind of feedback you get with cheaply made wires, faulty shielding, or just over all unclean power. I used to be in A/V sales so I know whats going on. I checked the cable I was using to connect the receiver with my ipod, no feedback. I then decided to unplug my laptop from AC power and the hissing went away. Plugged it back in, it came back.

I thought maybe the power from that wall was bad, so I plugged into my home theater's power supply. Its one of those $500 monster component power supplies that cleans your power, the size of a vcr. All my other equipment plugged into it give 0 EMI feedback...That didn't help it either. Which leads me to believe its a cheaply insulated or made ac adapter.

on top of that, I've always had it on the ground. But today it was on the same level as the laptop and I heard a very loud buzzing sound coming from the brick. And it does this when the laptop is charging or already charged, doesnt matter.

So what do you think?

 

It reminds me of a problem I had with my old tecra notebooks (p4 and a9).

If you connect them to an external monitor while on battery, everything looks great. If you connect the power cord, you get a bad image (grainy with strange colors).

When you connect it to an un-earthed power supply it fine. So it seemed to be a grounding issue with the notebook (not the power supply because I tried a few different ones).

Anyway, I don't know how to fix your problem. Maybe try connecting the notebook to an un-earthed power source? (I hope this isn't bad for the notebook).

 

Maybe the computer needs to be grounded with the AC power

 

Hmm not a bad thought. To add to this;
Try grounding the laptop to your AV Amp (Like the turntable ground) and repeat the process to see it it solves the issue. If it fixes it, it's a ground fault error in your laptop.

 

sorry Im not familiar with power/electric terminology. ground fault error?