Did more intense tests, and results are that the noise exists anyway, but with the chipem expansion its more noticeable.
I found a few games that need 2MB chip ( f.e. Worms talk version ) ; i paint & make music on my Amiga, so i keep the Chip Mem expansion.
Maybe i should use the Multimeter on the running amiga but i am a little scared of that.
Anyway, a friend of mine has an A1200 in his basement ( he never uses it,
) but i will ask him for the Power Supply to try.
That will be interresting
I report back. ( can take a while, because my friend is now on vacation )
Greetings and HUge Thanks from Me, Nibbler