I believe you're right, that is also, where the third prong on the AC line 
connects to the case, if I recall. My current switching power supply doesn't 
even have a grounding lug on it anywhere, I would think that would cause 
ground loops using that.
----- Original Message ----- 
From: "Steve Forst" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, February 28, 2011 9:19 AM
Subject: Re: RFI Saga continued


> Tom,
>
> This isn't your amp, where  a few thousand volts are floating around.
> While you should always be careful messing around with this stuff, look
> at  it this way:  If you turn off the supply and unplug it from the
> wall, and your hand brushes against the a.c. plug, will you get fried?
> If you are super paranoid,  unplug it and measure the voltage at the
> plug, which will be zero, and proceed.
>
> I do think you should tighten this thing up.  I'm not sure it is even
> the "official" ground lug.   On the inside it is holding a small thingee
>  with wires connected to it.    I'm not positive, but it may well be
> where the
> third wire of the a.c. line connects to chassis  ground.
>
> If it were me, I'd tighten it up and ground to one of the cover screws.
>    And since you  don't know you're own strength, just tighten good and
> snug, you're not torquing down head bolts on a Mack truck.
>
> 73, Steve KW3A