Buzzing\Humming when FDS is connected

[zmaster18]

Whenever the FDS RAM adapter is plugged in, there is a buzzing sound through the TV speakers. But once I unplug the RAM adapter cable from the disk drive the sound is gone. Sometimes putting a controller in the expansion port makes the buzzing louder or quieter. What's the cause of this? This happens on 2 FDS units I have and 2 Famicoms I have.

I'm pretty sure it has to do with a ground issue.

[petsematary]

Are you using AC adapters for both? Are they quality AC adapters?

[zmaster18]

I tried different AC adapters for the Famicom, and there was no difference. For the FDS, it doesn't make a difference whether I use an AC adapter or not.
Post Merge: July 12, 2015, 11:00:52 am
I solved the problem. I wasn't using the official AC adapter, the one I was using had this rating:

AC 100V 50/60Hz 6VA
DC 6V 300mA

When I turned up the volume, even without the RAM adapter there is a quiet hum. When I turned on the microphone, my TV speaker blasted me so hard I hit the wall and my cat ran away. So I tried the official AC adapter on all my Famicom stuff and now everything is perfectly quiet. Looks like I should just throw away this crappy AC adapter.