Chosen Solution

My old monitor shows green light in standby but screen is black then after 15 secs the light turns red. I can’t therefore get a picture.

@brycey for a Pioneer you would have to start with something like this

As you can see it can get pretty involved. You do want to take follow this flowchart and let us know what you get etc. Post plenty of pictures of your boards etc. With your question so we can follow you and assist you if possible. Adding images to an existing question