THIS IS A REPRODUCTION PROJECT MADE BY @caius ALL INFORMATION HAS BEEN POSTED WITH HIS PERMISION. CREDIT AND MERIT GOES TO HIM.
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 workingcustom 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!
This project started when, during my repairs, I came across these two PCBs.
Blood Bros:
Raiden:
Both were faulty.Blood Bros played blind :
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 workingcustom 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)
