I see that you are trying to use the HDMI to component adapter, when you get the "weak or no video signal" make sure your cable box is powered on. Below are some helpful links;
Sling Media Support Team
Got a new M2 and purchased the Gang Hu splitter as recommended by Slingbox.
Connected as the below according to Gang Hu splitter instruction:
Finished setting up the Slingbox M2 and Audio can be heard in Slingplayer (iOS and Web) but No Video:
Appreciate the Forum Gentlemen to help or Slingbox/Gang-Hu to advise, thanks!