Fri, 10 Mar 2017 14:55:06 GMT in alt.home.repair, wrote:

On Fri, 10 Mar 2017 10:55:09 -0000 (UTC), Diesel
wrote:


Fri, 10 Mar 2017 07:55:44 GMT in alt.home.repair, wrote:

On Fri, 10 Mar 2017 01:58:15 -0000 (UTC), Diesel
wrote:

I prefer the ones that dont, because, sometimes, the
3 prong ones generate unwanted background hum when fed to
external audio amplifiers while plugged into their chargers.

That implies that the ground is connected to the DC common. Not
sure why they would want to do that unless it is just for RF
filtering.



I've suspected the issue is a ground loop based on prior
experience with that...I haven't tried to open one of these and
take a look inside, so it's entirely possible it is connected,
but, due to some filtering circuitry in between, I'm unable to do
a simple continuity test on it. By unable, I mean that it doesn't
read as completing a circuit when tested in that manner.


http://www.channld.com/hum.html

This works well to remedy the problem...

https://www.amazon.com/Mpow-Ground-I...stem/dp/B01939
3MV2/ref=pd_lpo_107_bs_img_2?_encoding=UTF8&psc=1&refRI D=H7D9H4F6E7
CCRCVEDNNN


Reading with a meter you will be looking through the filter so
YMMV on what kind of continuity you see but at 60hz there will be
some pass through. I have had that problem with desk tops that
feed amps, particularly if there are other things in that loop
like a TV.

Same here. When I routed a friends computer thru a mixer board into a
stereo system, we had the ground loop hum issue to deal with. Oh the
joys of a semi digital recording studio.





--
Sarcasm, because beating the living **** out of deserving people is
illegal.