Today a quick test of some new modules.
1 ok, 2 ok … i have 10 modules working well 
but now it’s been 4 hours that I got annoyed on a dual ADAR (which I have however already done several times and not a very complicated circuit), the 1st works well but the 2nd not at all !
this is the same circuit 2 times, I have re checked everything over and over again, re done some soldering, change the TL072, continuity test, …
and i have some strange negative voltage with the multimeter by comparing with the one that works
Example, i test with a constant gate on each, and i’ve near +10V on the one that works and on the same opamp pin but on the one that does not work gives me -10V … ???§§§?././/??
at this time I don’t understand anything anymore, I’ll watch it tomorrow again.