I have bought an function generator off ebay (FY3224S). But when I measure the output voltage at the BNC connector, my oscilloscope says the output is a (slightly distorted) 50Hz sine of almost 300v!? Almost gave a a heart attack when I thought of my poor scope.
I should mention that it's powered by a 2-prong mains cable, and it has it's own internal power supply. I measured the internal commons, and they are all interconnected, at least the DC part is.
The internal power supply circuit has a little clip attached to the common that looks like it's supposed to be connected to earth ground, but since it's powered by 2 prongs there is no ground. Google tells me that function generators are usually floated, but in this case 300V seems a little excessive. I'm afraid I'll fry every circuit I'll attach it to.
Could I replace the 2-prong with a 3-pronged plug and then attach earth ground to the common to force it down? However my oscilloscope's BNC mantles are also earthed and that doesn't seem to make a difference.
I hope you guys can tell me what to do.