May 242015
 

Antoher board from the same batch of Sega System18 motherboards.

Ths is the time of a Taito F3 game (PCB version), Arabian Magic to be precise.Hardware is quite powerful as you can see from specifications:

  • CPU: Motorola MC68EC020;
  • Sound CPU: Motorola MC68000;
  • Sound chip: Ensoniq ES5505 and ES5510 (DSP);
  • Video resolution: 320×224;
  • Board composition: Board and F3 cartridge;
  • Hardware features: four scrolling layers, two sprite banks, Alpha blending

Board was in good condition :

Arabian_Magic_PCB_

It worked fine except for two stuck intupts (P1 and P2 2nd button) as you can see from I/O TEST mode:

stuck_inputs_

In this kind of hardware all I/O (and watchdog, too) are handled by a custom ASIC marked TCO640FIO (120 PIN QFP package) @IC71:

TCO640FIO

All the inputs from JAMMA connector are connected first to pull-up resistor arrays so I checked them and they were good.Lastly I lifted involved PINs from ASIC but inputs were always stuck.So, at this point, replacing the ASIC, taking it from a donor board, was my last resort.So, time to remove and replace it:

TCO640FIO_removed

and…success!All the inputs were restored and game fully enjoyable!

working_inputs_

 Posted by at 10:33 am