Konami Twin 16 Conversions - Gradius II / The Final Round

[NEON_Arcade]

This forum has had my digging through my old boardsets in an attempt to make more projects for myself.

One of them is a Konami Twin 16 Final Round board. I know this is the same hardware as Gradius II / VV, and that conversions have been commonly done via a romswap on Dark Adventure and Hard Puncher boards.

However, there were multiple revisions for this hardware, and the set I have is a GX870, which is the two board, rather than the three board version. I cross referenced the romsets and pals between the two versions of Hard Puncher / The Final Round and they are incredibly similar. This lead me to wonder if it would be possible to get Gradius II running on the Final Round GX870 revision (which seems to be come up for sale more often than the 3 board version), as it seems to have all the space needed for the extra eproms required for Gradius.

Before I attempt to tackle this, I figured it was worth asking if anyone with more conversion experience has already given this a shot and found it to be functionally impossible already, or if they have any insight into existing Twin 16 conversions.

 

[darkchao]

I've got the same board set, a 2 PCB version of The Final Round - I'd love to attempt the same conversion on mine. Hoping to get a little time this weekend to see if it's feasible.

 

[Apocalypse]

Only the Japanese versions of those games are convertible as they run on Twin 16 hardware:
- Hard Puncher
- M.I.A. (Missing in Action)
- Cue Brick

Export versions of those games were released on a slightly different hardware with only one CPU.

That said Twin 16 hardware comes in 2 or 3 board stack, the third one at the very bottom holding graphics data on a trillion of 27C512. It can be dropped and replaced by four 27C400 chips on the middle board.

 

[Aladdin2]

I have been workin

I've got the same board set, a 2 PCB version of The Final Round - I'd love to attempt the same conversion on mine. Hoping to get a little time this weekend to see if it's feasible.

I have been working on my two board set of "The Final Round" that looks like somebody already tried to repair. The issue is there are vertical lines in the video but red, green and blue color palette looks good. The GX870 main board is silk screened "GX870 PWB351311A" and the rom board is silk screened "PWB350958 ROMBOARD 34M". All RAM and ROM tests pass diagnostics but I think there is a defective static ram someplace. Does anyone have an idea which location on the board is the issue? The main board will display blocks of an overlay with lines in the video thus narrowing the issue down to the main board.