This board had no sound, a common fault with Double dragon boards.
I Replaced the 3 op amp IC’s as they were giving no output and the sound is fully working again.
Nice and easy
The game had way too much yellow on screen, almost impossible to see anything other than yellow.
I Traced blue/green circuit back to palette RAMs K8 and K9. Both looked fine on the scope so had to desolder the pair of them. The RAM at K8 failed a test . Socketed and replaced the faulty RAM with a 2018 and tested.
All working fine
This board didnt boot at all, looking underneath it was obvious why. There was a huge gouge in the board right down to the board fibres that cut through about 15 tracks.
It was just a simple case of reconnecting these tracks with Kynar wire. The board now boots and plays fine.
This board has had some repair work done on it before and not very well but I’m not too happy about messing with it just now so ill leave it alone.
Game has jailbars through all of the sprites both in game and in the title scenes.
First off, I put the board into test mode and let it run its maskrom tests. ROM H6 showed up as being bad.
These maskroms are compatible with 27c400 eproms. Removed the maskrom and burned a new eprom from MAME. Game now runs fine.
Game looked fine initially but when starting the game and on one of the intro scenes, the sprites had jailbars in them.
After a couple of frustrating hours figuring out what to read the maskroms as and if they were in the right places I settled on reading them as 27C040.
Three of the masks on the B board dumped fine but one of them gave random junk out at every read so it looked ok on the logic probe but the eprom reader told a different story.
Hunted out an 27c040 eproms and burned a new chip from the MAME set, the game now runs and plays 100%.
