[morzh]

I thought from your post that you did connect positive to GND?

Here's how you can think of it: Unless you have another source of negative, the most negative point in your whole circuit is the negative of your rectifier. This is as negative as it will get. Now, the cap is decoupling the low value resistor's (this is usually the big powerful one with taps) leftmost point, the GND, towards the neg. of the rectifier. Whatever current flows through it, being sunk to the negative, it will create a positive potential on its other end, the GND, meaning that whatever it is there, it is positive towards the Rect. Negative.

Hence, PLUS of the cap is on the GND.

So, your