Is there an in-universe explanation for why Vader's chest lights sometimes blink and other times do not?

Question

In A New Hope, Vader appears to have no lights at all on his box. In The Empire Strikes Back there are lights on the box but they do not blink, and in Return of the Jedi they blink.

I'm looking for an in-universe explanation, not just something about the movie's budget. :) I've read the Wookieepedia explanation of Vader's suit but I call BS on the whole thing. The way this entry describes Vader's weaknesses, he wouldn't have been effective at all following his injuries. That would completely negate everything in the EU which states how powerful he was and his further extermination of the Jedi. Besides, that entry doesn't address the light issue.

Answer 1

Well from that article:

One more change over canon is that the chest panel of Darth Vader's attire changed slightly from III to IV, and from IV to V and VI. The canonical reason for this has not been put forth. As well, the control panel from V and VI bore Hebrew lettering that can be translated as "His deeds will not be forgiven, until he merits."

So out of universe, it's partially budget and partially because Lucas loves to tinker with stuff. He's retconned entire plot points, so I don't think blinky lights gives him a second thought.

In universe, I don't see why it's hard to accept that his chest plate is a computer and computers can be changed/upgraded/modified over time. The three images shown in the question are clearly similar but also clearly not the same, so the suit is apparently an ongoing process. Without a detailed description of what the lights actually do in universe, it isn't really possible to say why they would or would not be blinking.