"Is it time to use the voltmeter and oscilloscope ? You need to find out which equipment is putting current into the chassis."
This is what i have been doing for the last 2 days, as well as fighting with other colleages whoes fault it is. i tested my equipment 4 times and they tested it 2 times. The funny thing is that my scope cozes problems if i connect the ground lead of the probe to the gnd pin of any isolated system. However testing it with the voltmeter it shows few millivolts between them.
I think the problem is always the mains or something to do with it, wish we have the batery operated scopemeter then i would not have this gnd problem.
Something even stranger happend, i could measure my box's signals with the probe without its gnd pin connected, if i connect the probes gnd to the my isolated gnd i get problems also.