24 Apr 2019

Wonder Boy - Sega 1986 (repair log)

Game was a conversion but not sure if official or not:
- game has 2 Sega daughterboards
- labels are handwritten
- program ROMs match the encrypted wboy romset

Anyway, sprites had horizontal bars over them:

I dumped the sprite ROMs but they checked ok, then reseated the associated daughterboard with no result.
So I followed the sprite generation circuit from IC to IC finding nothing obvioulsy wrong.
This is where I reached the 6 DRAMs used for sprites. They were AM2148 devices, known to generate a lot of heat, however two of them remained cold (IC13/IC33): to me that indicated those two chips were doing nothing.
I pulled them and installed fresh ones (much faster though being 35ns were original ones were 70ns) and sprite issue was cleared:

Lisenced... Clearly asking for a legal loophole.

I ended the repair by testing all inputs and sound and confirmed there wasn't any other problem with the board.
Game fixed.


  1. how do you play this on TV And which controller did you use and how?

    1. I play this on TV by simply using a supergun. Mine has DA15 ports compatible with Neo Geo controllers.

  2. i have this exact same issue, rams ordered will try it next week :)