Sunset riders freezing and reporting bad 12F and 12G (work ram)

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    • Sunset riders freezing and reporting bad 12F and 12G (work ram)

      Hello, some time ago I got a working - but in pretty bad shape - Sunset Riders PCB. Yesterday I was playing it and suddenly the game froze. After powering the board again it reported bad 12F and 12G srams. Running it again the game freezes but the music continues playing, and some times it automatically reboots.

      It seems to work fine after some time powered off, then after 8 minutes or so the game fails, when powering off and on it fails again, so this leads me to think some chips may fail with higher temperature.

      Voltage is fine (5.00V at the edge, I also rised it a bit to get 5.00V at ).

      - Those SRAM chips test ok in my Minipro, but they can fail under other conditions, isn't it? so I've ordered a replacement.
      - This board runs an overclocked 12MHz Motorola 68000 instead of proper 16MHz one.

      I've tried piggybacking 13F and 14F LS245 with no success.

      Any idea to diagnose the problem while the sram replacements arrive?

      The post was edited 4 times, last by rsignal ().

    • Try touching the ICs to see if any is unusually hot.

      68000 can be overclocked pretty well, so I don't think that would be an issue. I'd rather focus on the sram and any 74ls around it.
      * Arcade-projects, the site where you get the most of your arcade games.
      * If you want Drama go to Neo-Geo forum ---Darksoft
    • Hi, thanks for the tip. There was rust on several TTL chips, preventively I socketed and replaced them. One 74LS07 near a SRAM chip tested bad once, I replaced it but the board keeped crashing. Sometimes reporting bad G12, other times bad F12 and G12, specially after some use.

      You are right, I replaced the M68K but that didn't solve the problem. Anyway for future repairs I've ordered two Motorola 68000 16MHz from a seller that seems trustable (tomcat0101 at eBay), there are 10 units available.

      I think I found the culprit: rusted sockets for the program rom because I have reseated these eproms and now the board seems 100% stable... I played during some hours finishing the game twice.