Nov 152017

Maybe many of you will recognize this IC and throw up hands in horror:

This is the ‘infamous’ ‘HB-41’ used on several arcade PCBs (from Seibu/TAD Corporation but not only) :

  • Raiden
  • Blood Bros
  • Legionnaire
  • Sky Smasher
  • Toki
  • Dynamite Duke
  • Olympic Soccer ’92
  • Cabal
  • Heated Barrel
  • Operation Wolf

This analog component (20 pin SIL package) is used in sound circuit to mix background music and sound FXs as well as it acts as as filter of both.From my experience (maybe also others can confirm it) it’s a prone to failure part.Let’s take a look at what is inside it:

As you can see from above Hi-Res scan the custom is built around two ICs :  a 4560 dual operational amplifier (8 pin component on the left) and a 2060 quad operational amplifier (14 pin component on the right), both from JRC manufacturer.All the rest are resistors (also printed film ones, the black squares), ceramic and tantalum capacitors.In order to reproduce, after removed the epoxy, I pulled all the parts and metered them then I drawn schematics  :

Then I routed them ending up in a 5.3 x 1.8cm PCB:

More or less same dimensions of original part:

Here is how it looks assembled:

I used an LM358 and LM324 for my testing which maybe are not the best solution since the original OP-AMPs have both high gain bandwith (10MHz) but the replacement works well on all PCBs I tested so far.Here is testing on a Cabal, Blood Bros and Toki PCBs:

See you all to next reproduction project!

 Posted by at 10:28 am
Nov 092017

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

Blood Bros:


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 (with typical values of 4K, 2K 1K, 470 and 220 for the 5 bits of each color) 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:

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!

 Posted by at 4:36 pm
Sep 182017

We all know that Konami manufactured wonderful arcade games but, you know, beautiful things are often complicated too.And surely their hardware is! This mainly because of the use of many custom chips with the most disparate functions and shape.

The ‘052535’ is one of them, used on countless PCBs of ’80-’90 :

The ‘052535’ is basically a 5-bit video DAC (one for each R,G,B color) in SIL package used to convert the digital signals of the palette circuit into analog, we can see its pinout and implentation in this snippet from Lethal Enforcers schematics:

During my repairs sometimes I had to replace faulty ones so why not reproduce this part too?Perhaps someone else did it already but i did it my way.

First of all I removed the black epoxy to expose the circuit and scan it :

The black squares are printed film resistors, the part on the left marked ‘LF’ is a NPN transistor in SOT323 package, the four SMD parts are zero Ohm resistors.I metered the printed resistors (but first I removed the soldered parts to avoid interactions), this was the result :

As you can see the Konami ‘052535’ is nothing more than a R-2R resistor ladder with the resistors values tipically doubled (starting from 2.5KOhm up to 43.50KOhm).The NPN transistor (I marked it as a BC848 but it’s a NPN general purpose one)  is used in final stage to amplify the analog signal adapting it to RGB arcade standard.The circuit is very simple so it took few time to draw schematics of it and route them to a PCB which ended up with more or less the same dimensions of original part:

Sent it to manufacturer and after some time got the bare PCBs:

Here is the assembled reproduction, I used the legs from thru-hole components as pins which fit well in a female header: 

Testing on board was successul, reproduction validated!

See you all to next project!

 Posted by at 9:22 pm
Jul 212017

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

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!

 Posted by at 4:01 pm
Jun 282017

Got some months ago in a trade this pretty mint original R-Type board:

Board was faulty, it was stuck on this static screen:

System is made of three boards:

  • ROM board

  • CPU board

  • Video Board:

Swapping all the boards with a good set I could figure out that none of mine was properly working.So I started to troubleshoot the ROM board since it’s the most simple.The program ROMs were dumped as good but I found a bad 74LS245 @1A:

This gave me a working ROM board and a good starting point so I moved on to troubleshoot the CPU board.Analyzing the NEC V30 (uPD70116) main CPU revealed the interrupt line was asserted (active high on this CPU), here’s a screenshot from my scope triggered with RESET signal

The interrupt is generated by the uPD71059C  Interrupt Control Unit , probing it revealed that input pin 3 (READ STROBE) was stuck low :

This comes from output pin 12 of a 74LS244 @IC72 :

I pulled it :

It failed the out-of-circuit testing:

Finally the board booted but with multiple issues.First noticeable one was a totally missing sound but this was because the analog audio section was modified (by factory) to work in Nintendo cabinets.I simply reverted the mod by installing the missing capacitors @C101, C102 an C108 and removed the jumper wire:

All the other issues concerned the graphics.Some examples:

Honestly it would take too long to explain in details what I did (and maybe I even lost track of it…) before the board worked fine again :

All I can say is that I had to replace  in total 15 TTLs (all from Texas Instruments, are we facing another Fujitsu perhaps?)

But I claimed victory too soon , the board went bad again showing jailbars all over the screen:

I quickly pinpointed this further failure in one of the two ‘KNA6034201’ custom tiles generator on video board:

Testing it on a Kung-Fu Master PCB  (where it’s used for sprites too) gave me confirm it was really bad :

Looking at this PCB I noticed that the other custom ‘KNA6034201’ was replaced by a little sub-board:

Technically speaking the custom acts like a big shift register, it can take up to 24 bit of data from tiles or sprites ROMs, here’s snippet from R-Type schematics  :


As you can see in the sub-board picture above the custom functions have been reproduced using six 74LS166 with common shift load and clock signals.So I wondered myself : why not reproduce it in a more modern way?I fired up my CAD and drawn schematics :

Routed them to a PCB layout :



I sent files to manufacturer and after some time I got the bare PCBs:

Here is the final result compared to orginal custom:

Luckily I made no design mistake and testing was 100% successful.Another board repaired and another custom IC delivered to eternity!


 Posted by at 7:36 pm