Jan 162018
 

Raise your hand those of you, arcade enthusiasts/colectors, who have never dealt with the Konami ‘054986A’ and ‘054544’ audio modules?I think none…

This little project needs no introduction and technical explanation, we have treated this topic many times during our repairs.I simply reproduced (be careful, not reverse-engineered!So my repro still need ICs of original, especially the ‘054321’ ASIC) my way both modules with same results of original parts.I hope this will be useful for preservation purposes of our PCBs.

 

 

 Posted by at 11:24 pm
Jan 082018
 

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, 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 conlcusion 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 common cathode diodes :

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!

 Posted by at 9:13 pm
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 it, 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:

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 (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:

http://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!

 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