I'm having this problem when exporting the project. I'm working on a 8' x 4' info sign on Arcmap 10.2.2. I have tried exporting jpg, png, pdf without success. Also tried some recommendations for dashed lines found in another forum. I'll appreciate any help in the matter.

It's just that your question is confusing me because you mention dashed lines.
Ok sorry, in another discussion somebody had problems with exporting dashed lines. I'm not working with dashed lines.
I mentioned it, only for reference. This is my fist question here, some forums don't work with question already answered. I was trying to make reference to that discussion adn say that it didn't resolved my problem. 🙂
Is there any reason why you need the round line caps and joins? Do these indentations appear at line breaks, or are they random? Are your line4s snapped to each other, or is it possible that there are tiny gaps between line end points?
Because of the line width the square caps produce the problem presented in the picture below.

Oh ok, it's starting to get a little clearer now
. Can you just check that your line end points are snapped to each other?
Yep their snapped. In the photo the problem occur in various places in a single line.
If you dissolve (un-split the lines) the effect will be less.
Possibly not the best solution, but what if you buffer the lines and dissolve them (or draw them without borders) would that solve the problem of visualization?
Didn't work