This is another little reproduction project that arose during my repairs.

Some time ago I came across an Heavy Unit PCB which played fine except for the inputs that were not working.This had an explanation:

This SIL custom (in ZIP46 package) marked ‘MC-8282’ was broken in half.Like the silkscreening tells (I/O), this custom handles all the inputs.I looked into my spares and found some Kaneko boards that used a similar custom with same number of pins but marked ‘MC-1091’ instead :

I tried it in my board and all inputs were working again so I came to the conclusion that the ‘MC-8282’ and the ‘MC-1091’ are essentially the same.Not happy enough, I  decided to try to reproduce it.As always in this case, I first ‘stripped off’ the component by removing its coating and did some hi-res scans: 

As you can see from above picture, the designers pratically embedded in a single component a typical inputs circuit that can be found on many arcade boards.Techinically we can think of this custom like a big multiplexer made of four 74SL253 TTLs which receive on their inputs the signals from JAMMA edge connector.Obviously there is a common output enable signal and two selection ones as well.All other parts are printed film resistors (the black squares, the tiny ones are for pull-up), ceramic capacitors (for by-pass and signal filtering) and a couple of SOT-23 parts (involved in P1 and P2 coin input) which I was able to identify as dual diodes  common cathode  :

I fired up my multimeter in continuity check and in some time figured out the design so I made some rough prototyping on a breadboard:

I had success so I start to draw schematics.I intentionally omitted some not vital parts (like the many ceramic capacitors) and used SMD resistors arrays, this allowed me to save room on PCB layout and keep the same dimensions as the original part.I sent the design to manufacturer and received the bare PCBs after some weeks:

I assembled a unit:

and installed it on PCB:

Testing was successful, all the inputs of both players (plus SERVICE ) were correctly mapped and working:

For reference the MC-1091/MC-8282 custom can be found on these Kaneko/Taito/Toaplan PCBs (list can’t be incomplete so other additions are welcome) 

• The Berlin Wall
• Magical Crystals 
• Bakuretsu Breaker 
• Blaze On 
• Shogun Warriors 
• B.Rap Boys 
• Great 1000 Miles Rally 
• Bonk’s Adventure 
• Blood Warrior 
• Jackie Chan
• DJ Boy
• Gals Panic 1, 2, 3
• Air Buster
• Snow Bros
• Heavy Unit

See you all to my next reproduction project!

This project started when, during my repairs, I came across these two PCBs.

Blood Bros:

Raiden:

Both were faulty.Blood Bros played blind :

While Raiden lacked of the BLUE color:

The culprit was the same in both boards, the ‘UEC-52’ (sometimes silkscreend on PCB as ‘HB-52’):

It was clearly faulty in Raiden and missing at all in Blood Bros:

This custom in SIL package is an RGB DAC  responsible to convert the digital signals of color palette circuit into analog, it’s used on some Seibu/TAD Corporation PCBs like :

• Raiden
• Blood Bros
• Sky Smasher

Some time ago I partially figured out the pinout and schematics/parts after removed some of the epoxy resin that encapsulate it :

As you can see it’s a 15 bit DAC whose design resembles the Taito ‘TC0070RGB’ : two octal D-type flip-flops , some printed film resistors forming resistor ladders before the output to JAMMA RGB pins.But there was also a third IC that I could not identify.At first glance I thought about some kind of darlington array to amplify the signals so I made a post on EEVblog asking for some help:

https://www.eevblog.com/forum/projects/how-to-amplify-ttl-logical-levels/

The user ‘stj’ (thanks again to him) pointed me in right direction suggesting that the unknown IC could be a 74LS367 used for video blanking.So I removed the IC from a working custom and was able to identify it as a 74HC368:

At this point I had all the info to complete my schematics in order to design a replacement, obviously I first made some prototyping on breadboard which went fine.Later I sent my project files to China for manufacturing and got the bare PCBs after some weeks:

Time to populate (in my design I used 74HC574 since it has more logical pinout compared to 74HC374)

Here is a side-by-side comparison:

Testing was successful on both boards (excessive brightness of recordings is an issue of camera, video levels are exactly the same of original part)

See you to next reproduction project!

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:

Tatsujin Oh repair log #1

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 :

• Three 74LS240 in SOIC20 package
• Three 100nF ceramic by-pass capacitors in ‘0805’ package
• Three (two 9 pins and one 8 pins) 4.7Kohm SIL bussed resistor networks for inputs pull-up (I opted for thru-hole ones to keep cost down, they can be salveaged from arcade PCBs)
• Two strips of 24 pins male rounded machine-tooled pin header with 2.54mm of pitch.The corresponding female ones must be used on the arcade 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!