In the Developer tools, Source tab, there are a list of Sources.
Expand the ‘webpack://’ source
Expand the ‘.’ folder
Expand the ‘src’ folder
Find your ts file that you want to set a break point in, and you are done.
Another option.. Angular Augury
Google Angular Augury.
It is a Chrome Extension.
Now Augury should show up in your Developer tools (in your tabs with ‘Sources’).
Using Augury, you can watch what is going on with your Angular as your pages run.