fitting LED’s is a doodle mate… remove built-ups and take away. install the LED’s with vhb tape, "they chain link". drill holes in fascia and drop each jumper cable through the hole to the back of the sign. connect them to transformer and power supply to transformer.
that’s really how it "should" work. but seldom goes just to plan. as guy says, defuser helps heaps. but getting a good template for the letters "already up" could be more hassle than its worth. (unless getting paid good money that is) 😀 you can sometimes get away without defusers, that takes careful positioning of the LED’s. If you do this it can sometimes be better because the bare led’s are that bit brighter.
the real problem with LED’s i see is dark backgrounds. i did a nice sign for a Friend with a brown backing board with white led’s… in short… it was crap. no halo, just a start light. i was using a defuser and that did nothing for it. you could actually see it was defuser from the ground. anyway… if dark background, ditch it and go for neon, light coloured background, you should be fine!
nearly forgot…. as guy says, check you can get to the rear of the sign easily before taking this on. "you need to hide all the wiring some place. 😀