Have you tried the MEN ac into the other 20Pfi?
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Well, at this point I can't really be certain about anything. I have tried it plugged into the other Furman, and no difference. All my experimenting so far points to the MEN, but I'll explore any reasonable advice given. What is certain though, is that no hum exist with the MEN out of the loop, or with it in the loop with a ground lift plug no hum exists.
Crazyeddie - A few years back I experienced a hum when I connected a component that utilized a two pin plug.
When used with my amp, which which had a three pin plug, a loud hum was present.
I disconnected the component and powered it up without connecting it to the system. I then measured the differential between the neutral side of the output jacks and the mains outlet ground using a digital multi-meter .
I found there was "noise" i.e. a voltage could be measured.
A note about meters - depending on their design, an analogue meter may not show any reading whereas the digital meter has a high input impedance, which allows it to more accurately record even the slightest amount of noise.
The simple cure in my case was to attach a drain wire to the chassis of the component and attach the other end to the ground of the mains outlet.
However - If the component in question uses a power cable that has a ground pin - there may well be some problem that should be addressed by a qualified technician.
Like you, I tried various noise defeating devices without success,
I do not consider lifting the ground of any component a wise move - it's there for your safety in the even of component failure.
Not sure if it will help, but its something else to try - good luck
@williewonka Thanks for the reply. My power cord IS a 3 pin, But you have given me an idea to try. It will be quite easy for me to try a ground line from the chassis, to earth, as my house main water supply line is in a cabinet directly behind my audio gear. I'll give it a shot when I get home tonight and let you know.
Even though the MEN has been "checked out", when it is connected via XLR it presents problems
Perhaps you could verify it's OK by doing the following using a digital multi meter
- disconnect the MEN from the system
- power it up
- for each XLR input and output measure the differential (AC and DC) between the mains ground and the ground pin on each XLR socket
- if there is any voltage there is a problem
Perhaps when it was "checked out" the techie only used RCA?