An alternator requires power so it can begin to make power. Taking the power from it and then running the engine will not show anything.
Disconnecting the battery with the engine running, is a good way to #### a regulator.

May I recommend you visit an Auto Electrician and pay to get the problem fixed. In the long run it will work out cheaper as you will save yourself time and headaches and money on Panadol. Just a thought. Reason being, is that it looks like you are causing more problems in an effort to fix the original one.