Today I’ve dumped the only PAL from a Truxton II/Tatsujin Oh PCB.Original device was a registered but unsecured PALCE16V8H so I could read it straight in my programmer.Dump is not tested since the PCB is not working but should work on a PALCE16V8 target device or a GAL16V8.Any feedback is welcome.
Got in the mail today this Tatsujin Oh PCB (japanese release of Truxton II), a great vertical shoot ’em up released by Toaplan in 1992 :
The board was bought on eBay and according to the seller it didn’t accept credits.But actually, when I powered it up, it booted to a ‘TILT’ message screen and then kept resetting in an endless loop:
I have experienced this issue many times and the culprit was always him, the “infamous” ‘HK-1000’ :
This custom IC handles all the inputs including SERVICE, TEST and TILT and it’s a very prone to failure part, especially the first ceramic revision (like the one present on this board) cracks very easily or goes internally bad.As you may know, I have done a reproduction of this custom IC so I installed a unit after removed the original part and put some round machine pin headers :
Board booted now into game and correctly played but audio was loud, especially explosions and other sound FXs :
As you can see in above video I could not even adjust the volume by acting on the 1K potentiometer :
So I removed it:
It was broken as it fell off in pieces :
I installed a good one:
Sound was fully restored, board 100% fixed.End of today job.
Another board from the ‘portughese’ box : Tatsujin Oh, a great shoot ’em up released by Toaplan and known outside Japan as Truxton II.
Board was booting but sprites were mostly missing and other GFX glitches present too:
There was an obvious reason of this.The custom ASIC ‘GP9001’ (which is the graphics controller of the system) was damaged : some pins were missing, other bridged, two traces going to it were ripped too.
Here’s a close-up under a microscope:
Given the extent of the damage the only possible solution was the replacement of the ASIC which is a very delicate operation (not for everyone…) because of its package (208 pins in a QFP package with very fine pitch).For this purpose I’ve been sent by the owner a dead FixEight PCB as donor:
I removed the damaged part and cleaned the area preparing it for the trasplant:
The spare removed from the donor board :
After soldered it I took care of rebuilding the ripped traces using some AWG30 wire :
Testing was successful, board 100% fixed.
As many of us know (not only long term arcade collectors/enthusiasts) Toaplan manufactured few but excellent games.Some of them can be considered real masterpieces like Out Zone and Truxton for example.Going into technical details four of them are united by the fact the hardware uses a custom IC to handle inputs: the ‘HK-1000’.I have partially covered this argument in my past repair log of Tatsujin Oh, you can read it here:
As said in the above post, two revisions of the HK-1000 were made with same functionality but different package.The first one was ceramic hence very fragile.This is used on Truxton II/Tatsujin Oh and FixEight:
The second one is more robust and it’s adopted on Ghox and Pipis & Bibis :
If this custom goes bad (like it happens very often especially on first revision) you will be no longer able to fully control the two players and in the worst of cases the board will be stuck on a TILT message.The only option could be find a donor board but we are speaking of valuable PCBs even if faulty.So some kind of replacement was needed.
There is very few info and documentation about this custom but it seems Toaplan engineers embedded on a single IC (the HK-1000, indeed) all the circutry they used to handle inputs (but also coin counters/lockouts) on previous PCBs (Wardner, Out Zone, Rally Bike and others too).I took inspiration from an Out Zone PCB to study the design:
As you can see from the above picture, I highlighted two sections of PCB : the blue one concerns the circuitry for coin counters/lockouts handling, the red one is for inputs (players direction and buttons, TEST, SERVICE, TILT).With this knowledge I started my tests.As testing platform I used a Pipis & Bibis PCB (the cheapest one which carries the HK-1000).I removed the custom and mapped some inputs following the above mentioned design:
This was successful so I started to draw and route schematics for a real replacement.I voluntarily omitted from my design the circuitry for coin counters/lockouts as it’s not a vital part (although I figured it out so I can implement it in a later moment).I sent the layout to a manufacturer and after few days I received the bare PCBs:
Very few components are needed to populate the PCB :
Here is final result after 5 minutes of soldering:
A comparison with original custom:
Testing on the Pipis & Bibis PCB was successful, all inputs of both players were correctly mapped and working as well as TEST, TILT and SERVICE ones:
As said, this is not a 1:1 reproduction of original part since coin counters/lockouts handling has been not implemented for now but it’s enough to salveage your faulty boards from uselessness.Stay tuned for the next reproduction project!
Some months ago I received for a repair this Tatsujin Oh PCB (known outside Japan as Truxton II)
As you can see from the above picture, the custom ‘HK-1000’ (used for inputs) in front of JAMMA edge was missing but this was not the main problem, board won’t sync up:
All the graphics and video timing signal (HSYNC, VSYNC, etc..) are generated by a large surface mounted ASIC (208 pins QFP package) marked ‘GP9001’:
You can find its pinout on page 32 of the Knuckle Bash schematics:
https://www.jammarcade.net/files/Schematics/Arcade/Knuckle%20Bash.pdf
The IC was previously reworked by someone in a bad way, many pins were bridged together, flux residuals were not cleaned.So I decided to remove it :
and solder it again:
Happy with the result I powered up the board again and I was greeted but this static garbage screen:
Probing the main 68000 CPU revealed no activity on data bus.Doing a visual inspection of PCB I found a couple of severed traces on solderside just around the CPU area:
Patching them allowed the board to boot but, obviously, due the lack of the ‘HK-1000’, the game was stuck on a ‘TILT’ error message:
Input check in TEST mode reported ON most of them :
Now some words on the ‘HK-1000’.As said, this custom handles all inputs and it’s has been adopted in later Toaplan PCBs.There are two revisions of it, the early one has a ceramic package and due this nature it’s very prone to damage and failure.This revision is used on Truxton II/Tatsujin Oh and FixEight:
The newer revision is more robust and it’s used on Ghox, Pipi & Bibis:
Back to repair, from available info it seems the functions of this custom can be reproduced using a couple of 74LS240 (actually the custom handles also the coin counters and lockout but we can omit it), this is not a suprise for me since a lot of previous Toaplan boards use same design with these TTLs (see for example Truxton, Wardner, Hellfire and other).Doing some tests with a single 74LS240 I was able to successfully map some inputs turning off the TILT error
This allowed me to enter in game :
Later, owner of the board installed the missing HK-1000 and confirmed the board was perfectly working after my repair:
P.S.
I’m currently drawing schematics for the replacement of the HK-1000 and I will post here my results.Stay tuned.