It’s the round on the repair bench for an undisputed arcade masterpiece … Double Dragon!

It’s for sure the godfather of all the cooperative beat ’em up of all time. It was developed on 1987 by Technos Japan and distributed in North America and Europe by Taito.

The board was sleeping in my personal collection probably for over 20 years, until few days ago when a friend of mine Sasha asked me for this game. I “quickly” found it and i left it on the bench for testing.

The board was running fine, it can be coined up and both player controls were in working condition, except for a partially missed audio. The speech syntesizer section a couple of OKI M5205 seems working but the game is lacking of FM music, so it need further investigation and troubleshooting.

The speech FX were working so the coulprit should be before the amp stage on the audio chain of the board.

The audio section is populated by a classic arcade tandem: a Yamaha YM2151 FM synthesizer and it’s trusted and partially scratched DAC friend YM3012. Both chips were already socketed so they can be easily swapped.

I started the troubleshooting at the end of the audio chain, i put the oscilloscope probe on the YM3012 DAC i looked at its inputs and outputs. The IC was getting some kind of data on its serial inputs but the outputs was totally silent. The chip is mounted on a socket so replacing it was a few seconds job, so i swapped it for another working YM3012, ad gave it a try … finger crossed … as usually 🙂

GOTCHA! Now the board is playing music too!

Another case closed … but looking at the board something is keeping my attention high …

a DIP40 IC package marked ENC EL1200AR … mmmhhhh … interesting custom chip i was thinking, but a deeper looking at the integrated circuit reveals that the chip has a scratched/sanded surface with a rebranded label ID. Searching on google didn’t produce any useful information, also other bootleg pictures seemed not to be useful, different bootlegs were made according to MAME source. We can find almost three kind of bootleg boards running almost the same software and hardware they seemed to differs only by the SPRITE CONTROL CPU:

  • HITACHI HD63701 (same as the original board)
  • HITACHI HD6309
  • MOTOROLA M6803
  • MOTOROLA M6809

The boards equipped with the HITACHI chips share the same two PCB sandwich layout like the original one, the boards equipped by the M680x should be on a single PCB.

Dumping the program ROMS and comparing them against ROSICA gave me different matches, most of them were present in both bootlegs and original boards too. The comparisons helped me identifying the RomSet almost identical at the “ddragonb, Double Dragon (bootleg with HD6309)” present in the MAME driver except for the i2 ROM that gave me no match. The i2 ROM is the one labelled “32″ on the picture above. 

If i weren’t wrong i think i should own another Double Dragon board, and i started searching for it wondering if its PCB was made with the same layout, ad i found it. Both boards are identical, but the newcomer isn’t equipped with the unknown EL1200AR but with a scratched DIP40 ic mounted on a socket.

The markings seems to be gone, but using some water some clues can be spotted.

As you can see, superimposing a good known chip marking using Photoshop reveals a quite perfect match, the misterious IC is a sanded and rebranded Hitachi HD6309.

Now it’s time to write down a MAME driver for this ROMSET, with a special looking at the different unknown i2 ROM found.

Looking at other boards pictures on the internet reveals another big question mark laying on the bottom PCB. This board is populated by half of the EPROMS like other boards, very strange … maybe this bootleg was missing something? The board on startup is performing a self test by testing some IC and all EPROMS and they were reported as good, but as we know, we can expect the unexpected by bootleggers!

As you can see the GFX EPROMS (6) on this bootleg are 28 pin IC and according to MAME source they should be about 6Mbit graphics so we should find 12x512Kbit EPROMS, same as the original board too, or 6x1Mbit, but standard 1Mbit EPROMS like 27c010/27C1001 are in a 32 pin package and not in a 28 pin package, with this package we can find at least a 27c512 EPROM but 6 of these doesn’t have enough room for all the gfx…

These custom EPROMs/MASKROMs are marked EN4068 and they should be a 1Mbit devices on a 28 pin DIP package, i tried to read one of them on my LabTool48 Programmer using auto ID the software reports as device Manufacturer/ID 0x22/0x22, maybe it could be useful for someone out there, or maybe this information could be totaly useless too.

Reading it as a 27c512 gives a consistent read but probably only on one half of the data, looking ad the 27c512 pinout no pin is unused, maybe one of its control pin 22(G/VPP) is used as A16 to address up to 1 Mbit data. It needs further investigation … here is the pinout:

Notice: the board is populated also with some custom resistor arrays marked ENC-2.

… but now it’s the time to deep test the board! 🙂