Entropy International coin doors appeared most Bally and Williams games from around 1988 until the end of production. There are two types: two/three slot with one coin return, and a DBV (dollar bill validator) door.
Entropy doors usually have a distinctive diagonal “QUARTERS” insert (but I’ve seen this on other makes, too).
Two-slot W-logo Entropy door on a Swords of Fury. Shark sticker not original. Door also appears to have been painted. Picture by Chris Kuntz.
When Williams started using these doors in the U.S., they used a three-slot door with a two-slot entry housing covering the center hole, with their logo cast into the center. This is a pretty sharp looking part, and expensive.
After Williams acquired the Bally name, a few Bally games used this door with a B logo. These are relatively rare, since only a couple games used them. IPDB shows an Atlantis with this door.
Likely, cost reductions lead to the two parts being merged into just one no-logo part. Some of these featured a sticker between the two slots advertising 50/75/$1 pricing.
Some countries use this door with a 3-slot arrangement, where the center entry is a third coin. I have only seen this on re-import games.
My Twilight Zone was a re-import from Spain and came with one of these doors, although I suspect it is not original to that game. But this indicates they were also likely available in Europe as well.
DBV door on a Road Show.
Around 1993, games transitioned to having a DBV. During this time, Williams used Coin Controls doors, then switched back to Entropy doors.
Later Entropy doors had ridges on the coin returns.
Entropy doors always have orange inserts.
I’ve listed these on the same page because they have a fair amount of common parts, particularly in the coin entries and return buttons.
Some parts are available from Pinball Life.