Electronics person needed

Hello. I'm looking for some electronics dude.
I've just stopped testing some diodes I meant to build into my chassis lid. But something odd happened.

I was testing how well the light works on the different colors (3 colors in 1 plastic casing) if using more at once as I earlier had used some where red would cause the other colors to not work.

But I found something really odd. I tested using an antec psu I had spare. Put the resistor between teh psu and the common negative pin.
Before I even got to connect another wire, it was lighting up! When I was touching one of the other pins the diode would work. I grabbed my multimeter, and discovered that between the negative (12v line's negative wire on a molex plug) and me/ground I had 110v AC @ 12-13hz and enough amperage to actually power the diode.
Next I noticed, I had forgotten to turn the psu on! When I did that, I had 53-54v AC and a lower herz number between the negative/ground and me.

Why is that? What's going on? Is that normal, or is my psu broken?

I'm living in denmark, so my wall plug delivers 220-230V @ 50hz - guessing the 110v reading and half herz is something the psu does because if the rectifier inside, but why's it output that kind of voltage when it's off in the first place?

I bought the diodes a few years ago (and just never used them), so I have no data on them, except that it's a quadratic plastic casing with 3 diodes inside sharing a single common. I got some resistors with them that would work with a 12v source. I forgot the color code stuff I learnt in 97 many years ago, so no idea what ohm they have. The colors are : green brown black black brown ..... or ther other way around. Dunno from which end to read if the last ring isn't silver or gold.
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  1. Nobody who knows something?

    I did finish the testing, and the leds work as intended. But I still don't understand why there's power while the system is off.

    I have to say that my multimeter is fairly elaborate though. It can measure static and stuff as well as simple things.
  2. You need an electrical engineer, not a buncha hardware enthusiasts^^
  3. I did try that.
    Where I work we educate electricians and the like, and I asked a bunch of them. They didn't have any conclusive answer.
  4. http://www.badcaps.net/forum/

    any electrical questions they will know
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