Guys, thanks for the replies! Based on your comments and my own research, these are the conclusions that I have come up with so far (To avoid any confusion, please let me state that 'Wii Power Brick' means the standard Wii power connection which is actually a DC Converter that expects a 110V 52W 60Hz AC power supply and outputs 12V 3.7A DC current to actual console) -
1) Its very unlikely that root cause of the problem is due to cheap Voltage Converters that I am using. However, is it possible that cheap Voltage Converters have some basic design flaw that manifests itself as this problem while using with Wii Power Brick? Is it advisable to pursue for better and more expensive Voltage Converters?
2) I suspect that as SuperCzar is suggesting, Wii Power Brick might be leaking AC current. Maybe brick works fine with US power supply only (60 Hz). Combination of Indian Power Supply (50 Hz) and Step Down Voltage Converter might be making Wii Power Brick malfunction and making it leak AC current. I don't have a DMM myself, I will have to go to some electrician to do the test SuperCzar is suggesting. Most likely this electrician will be dumb and I have myself never used DMM before. So if you have more specific instructions for DMM testing, please give them to me now. Most likely I will go to electrician either today or tomorrow evening.
3) If DMM test reveals AC current is leaking then I will have to replace the Wii Power Brick with best quality 220V voltage compatible Power Brick that I can find (this is what KingKrool is suggesting). I guess it will be something like this -
Buy Electronic Auto AC Adapter - Order Now!
Most likely, I will buy it on Saturday from Palika, Delhi.
4) If DMM test reveals no AC current, then the problem is within Wii console itself and there is nothing I can do about it. No point replacing Wii Power Brick then.
5) Guys, I told you that I was using 20W Voltage Converter before. Since Wii Power Brick is rated as 52W, is it possible that I have somehow damaged Wii Power Brick or Wii Console by under powering it? Could that be the root cause of problem? I am feeling guilty for this carelessness of mine, I have bought a 50W Voltage Converter now.
6) Now something worth pondering - Is this problem really a problem at all? In my Audio-Video setup, all AC plugs ( of TV, AV Receiver, DVD Player, Wii Console) are 2 pin plugs. There is no ground connection. When Wii is powered and I touch metallic surfaces in Audio-Video setup, I feel slight electric current. This is because by touching, I am grounding the leaked voltage from Wii. If I don't touch it, then there is no grounding and hence no extra electric current within my AV setup. That means my AV setup is safe as long as I don't touch it! So problem is not a problem at all if I don't touch anything while playing Wii games! What do you think?
Waiting for your comments/replies!