Yes its the first case. .... the problem occur when I connect it with the mixer... even if the mixer is powered off the duplicate projection screen goes off. i think you are right Sir... I should buy ground loop isolator..
[Moderator note: moving post to Home Audio - more applicable category than Laptop Tech Support.]
I have DELL laptop Inspiron 15R Intel core i7 with AMD RADEON Graphic card -Realtek high defination audio-window-10. when my laptop is connected with Multimedia projector screen the duplicate...