(Topic ID: 307484)

sys11 b - u25 ram failure

By mr-zed

1 year ago

Topic Stats

  • 8 posts
  • 4 Pinsiders participating
  • Latest reply 1 year ago by mr-zed
  • No one calls this topic a favorite


Linked Games

No games have been linked to this topic.

    Topic Gallery

    View topic image gallery

    A52D2901-6643-44E6-A9C5-8E0408F001FE (resized).jpeg
    34E0F643-673D-4913-A707-11530DCE2621 (resized).jpeg

    #1 1 year ago

    Hi there!

    I have a Banzai Run game that will not boot.
    I get U25 ram failure.

    It have been unused and waiting for restore/shop for 4-5 years. I have turned it once in a while with no errors. Guess about a 6 months ago last time.

    The batteries was removed when I got it, but there is a bit of corrotion on the board.

    replacing the u25 ram with a new 6116 ram did not make any difference.

    I only get 4.86 volts from the psu - guess thats a bit low. Dont have any other system 11 games to test with.
    Is that too low and what could be the problem with the psu? (the 6057 is ok)


    #2 1 year ago

    Power measurement, that depends on where you measured. Should be seeing close to this:
    MPU IJ17 Pins 4,5,6 = +5.03 VDC @8.1 mV AC ripple
    U26/U27 ROM Pin 1 = +4.91 VDC

    If you measured 4.86 at the PSU you are going to probably find even lower at these points. BUT, the common symptom of low power is random resets and lockups. The failure you are seeing, my guess, is corrosion related most likely. If not, it could be another IC that is on the address/data bus that the RAM is having trouble with.

    #3 1 year ago
    Quoted from mr-zed:

    Is that too low

    Yes. Even if you get the game to boot, you are likely going to have crashing/reset problems running that MPU at this voltage.

    Think of things a little different. Your goal should not be to "just get the game booting"... It should be to make the thing reliable and play for years, moving forward.

    Honestly, I would suggest to resolve the power problem by buying a new one or repairing that one, then remove the batteries from the game and try to power cycle it quickly a few times and report here if there is any change. Those are the easy steps you can do on your own before you should assume the MPU has issues.

    Secondary issue to tackle later, your battery holder is likely not working unless you replaced it. You can buy a new one, mount it remotely or, if you are skilled enough to replace an IC, you can order and install NVRAM and you will never need batteries again.

    #4 1 year ago
    Quoted from mr-zed:

    The batteries was removed when I got it, but there is a bit of corrotion on the board

    Please post a picture of this board.

    #5 1 year ago
    Quoted from PinballManiac40:

    Please post a picture of this board.

    Here is a pic - the battery was allready removed, when I got the pin some years ago!
    Looking closer at the pic, the corrotion is quite bad - dont know if its fixable.
    Should have neutralized the board when I got the pin, but I didnt know or looked close at the board. Bad mistake.

    34E0F643-673D-4913-A707-11530DCE2621 (resized).jpeg
    #6 1 year ago

    Yes, its bad enough. That corrosion is likely to migrate, or creep, into many of those components, and possibly already has. It could cause many problems. There is a few good threads on the subject of correcting it properly on this site, in order to repair and ensure reliable operation in the future. In a nutshell, removing all potentially affected components, carefully neutralizing and removing all traces of corrosion, and reinstalling new components. Not an easy quick fix for this series of board, but possible.

    3 weeks later
    #7 1 year ago

    Update to the sys11 board.

    Removed the board and neutralized the acid.

    Yesterday I finally got time to trouble shoot.

    Using a scope, it was clear that some pins on U25 (address bus) was not receiving data.
    With a multimeter I could trace it to the u25 socket. Replacing the socket solved the problem and the mpu boots again.

    A bit of luck thats for sure.

    Guess it was a little hint for me to begin restoration of this unique piece of pinball history. Love Lawlors innovative ideas.

    3 weeks later
    #8 1 year ago

    Now I’ve done it!
    Mylar removed with no problems!
    A bit of glue remaining!

    Playfield is nice, but will need a little touching up/airbrush and some clearcoats!

    Hoping the first coat with thin clear will fill/remove the fine cracks in the clear on some inserts!

    Cabinet will need work also!
    Still deciding betweek repair and clearcoat, applying decals or use stencils as factory!

    A52D2901-6643-44E6-A9C5-8E0408F001FE (resized).jpeg


    Wanna join the discussion? Please sign in to reply to this topic.

    Hey there! Welcome to Pinside!

    Donate to Pinside

    Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!

    This page was printed from https://pinside.com/pinball/forum/topic/sys11-b-u25-ram-failure and we tried optimising it for printing. Some page elements may have been deliberately hidden.

    Scan the QR code on the left to jump to the URL this document was printed from.