(Topic ID: 293637)

F-14 Tomcat Adjust Failure on Startup

By F-14Pin

2 years ago


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    U25 Ram Pin 24_LI (resized).jpg
    U25 Ram (resized).jpg
    Sys 11 Board (resized).jpg
    Batt Holder (resized).jpg
    20210518_145623 (resized).jpg

    #1 2 years ago

    My F-14 Tomcat pin shows "Adjust Failure" whenever the power switch is turned on. A Google search pointed to this being a System 11 way of telling you that the game is not getting power to the U25 RAM chip when the game is off and, thus, not able to retain settings, high scores, etc.

    I replaced all three batteries and the battery holder doesn't show any signs of leakage or damage but this didn't fix the problem. I'm able to clear this using the black advance button inside the coin door but once it's powered off and back on the adjust failure comes back.

    From a Pinside Member;
    The power runs from the batteries to 1N4148 diode at D2 and then on to the U25 RAM on System 11 Williams games. Sometimes the “Adjustment Failure” reading can be as easy as just replacing the batteries, sometimes a bad diode at D2, or a bad U25 RAM chip. Sometimes, however, it’s loss of continuity between components or a bad battery holder. For this F-14, the battery holder was the culprit. It was pretty brittle and beginning to actually fall apart.

    Assuming my holder and batteries are good what's the fix for this? I'm not an electronics repair kind of guy so I'm kind of useless in this area.

    Thanks
    Dennis

    #2 2 years ago
    Quoted from F-14Pin:

    Assuming my holder and batteries are good what's the fix for this?

    Your next step would be see where you HAVE power. Use your multimeter and see if your batteries are actually providing voltage on the output side of the holder, at the diode, and at the power pin for the RAM at U25. Once you know where the power isn't getting to you'll know better what the next step is.

    Alternately you could contact ChrisHibler or Borygard and send the board out to have NVRAM installed and never be concerned with batteries again.

    #3 2 years ago

    You probably already checked, but is the battery holder making a good connection on the batteries? I have had some before where the prongs in the holder were either corroded, worn, bent, etc., and didn't actually make contact with the batteries.

    #4 2 years ago

    Also check D2 1N4148 diode tied to the batteries. They fail. But not often. As #grantopia mentioned, double check battery holder, especially if it's original.

    #5 2 years ago

    1) I have 1.6V across each battery

    2) I cannot find Item 41, D2, 1n4148 diode.

    3) Where do I read power at for the U25 Ram?

    Kind of stuck on steps #2 and #3 above. Where is that diode on the System 11 board?

    #6 2 years ago

    The paper sliver is by it.

    20210518_145623 (resized).jpg20210518_145623 (resized).jpg
    #7 2 years ago

    Found D2 and have 4.85V so Battery Holder is good and D2 is good. How do I read U25 Ram?

    Batt Holder (resized).jpgBatt Holder (resized).jpgSys 11 Board (resized).jpgSys 11 Board (resized).jpgU25 Ram (resized).jpgU25 Ram (resized).jpg
    #8 2 years ago

    Taken from Pinwiki.

    Testing for power at the RAM chip is easy.

    Set DMM to DC volts (or on less than 20V if not using an auto-ranging meter)
    Game off
    Black lead on backbox ground
    Red lead on pin 24 of the RAM as shown at right
    Three AA batteries normally provide 4.5VDC. If you are reading some voltage, but not quite 4.5VDC, the batteries need to be replaced...and don't forget to move them off of the MPU board while you are at it.

    Other causes for low or no battery backup power to the RAM chip are:

    Failed diode D2. This blocking diode normally prevents the 5VDC source from "charging" the alkaline batteries. D2 is a 1N4148.
    Failed diode D1. This blocking diode normally prevents the 5VDC battery backup power from powering parts of the board other than the RAM chip. In this case, the batteries will deplete rapidly. D1 is a 1N5817.

    #9 2 years ago

    After a lot of poking and prodding I was able to find 4.4V at both sides of D1, D2 and Pin 24 of U25. See picture for U25 pin I was reading from.

    I'm not sure if my DMM has bad leads or if the System 11 battery system is intermittent. Doing all these checks I had power than didn't, had, didn't and round and round I went. I didn't have power more than I did.

    Weird.

    I still have the Adjust Failure after repower.

    U25 Ram Pin 24_LI (resized).jpgU25 Ram Pin 24_LI (resized).jpg
    #10 2 years ago

    Sounds like your RAM could be bad. I’d try a factory reset. The chip is not socketed so I’d be sending it out for replacement and have them add NVRAM.

    #11 2 years ago

    The pin your arrow is pointing to is pin #1, hope that is not the one you were checking.

    #12 2 years ago

    Yes that was the pin I was checking, I'm assuming the opposite side is pin 24. I will re-check today.

    #13 2 years ago

    Who is the go-to person for board repair these days?

    #14 2 years ago

    Chris Hibler - CARGPB #31
    http://ChrisHiblerPinball.com/Contact ... for board repairs
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    #15 2 years ago

    Success for now anyway, want to thank everyone for helping me sort this out.

    I verified my DMM was working property but still had inconsistent voltage readings at the battery holder. Fiddled with the batteries, removed, reinstalled etc. and got a good 4.4V at the battery holder, D1, D2 and pin 24 of U25. Repowered machine and got "Adjust Failure". I than went into AD 70 and turned on "Factory Settings" and repowered machine and it cleared itself and was working as it should. I played a game than shut down and restarted and it appears to be working fine.

    Now I have the bug to get another pin, I had three at one time but sold two of them. Should have kept that Space Invaders wide body pin.

    #16 2 years ago

    Maybe some corrupt data got into the RAM and the Factory Reset cleared it. Glad you got it sorted out.

    Alkaline battery leakage is a leading cause of board damage. You can minimize the chance by replacing them with lithium, using a remote battery holder, or removing them completely and using NVRAM.

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