Zaccaria/Associated Leisure MVGS Neptune Maintenance 2019

26/02/2020 - Spare Arian Mission PCB #PA20200226

SNK Alpha Mission PCB SNK Alpha Mission SNK Alpha Mission, faulty

Since the restoration of the cabinet I'd been on the lookout for a spare Arian Mission PCB. It wasn't a common game and though I'd picked up a batch of two PCB sets originally, one of those was in poor condition and not working. eBay hadn't had any hits on one (under any of the three names, ASO, Alpha Mission or Arian Mission) since either. I did come across an old "for sale" post on KLOV for an untested Alpha Mission PCB set that I responded to and was still for sale.

On first power on the game booted up passing all self-tests with attract mode sound OK. Sprite graphics looked OK but the game was missing the background graphics plane.

02/03/2020 - Game PCB Repair

Alpha Mission socket replacement, before Alpha Mission socket replacement, after

Checking the graphics EPROMS on the bottom PCB found IC H14 EPROM data bus always high with noise. Removing H14 found several corroded pins and confirmed notoriously unreliable JAE sockets. Cleaning H14 brought some graphics back but stressing the PCB or EPROM impacted the display. Replacing all the graphics sockets with new resulted in all the graphics elements being present but with lines in sprites and intermittent text display due to corroded pins on more of the EPROMS. Since I needed to replace a number of EPROMS already to convert from Alpha Mission to Arian Mission I decided to program a complete new set of graphics EPROMS as well.

DataIO UniSite EPROM programming Arian Mission Arian Mission

To convert the title needed program EPROMS P1 to P4 and graphics EPROM P14 programming along with P10 to P13 to replace the corroded graphics EPROMS. With the new graphics EPROMS there were no further problems with graphics and the Arian title game title was properly displayed.

Arian Mission Arian Mission

The small LCD monitor was very overdriven by this game so the picture was very bright and bleeding making it hard to be sure the graphics were all fixed. To be sure I switched over the CRT monitor for final confirmation, that confirmed everything looked good.