Anyone ever encountered a problem like this on their Williams games?

[megamanmk2]

Hey, I posted a long while ago about my Defender machine, having never owned an old Williams cabinet I didn't know where to start. Ended up tracing problems to a bad decoder socket and it worked for almost a year up until recently.

The controls started working intermittently, so I removed the IO board and reflowed all the connector solder and it worked fine for a couple days.

Now it powers up fine, and will play for a couple minutes before hanging up and going into the rug pattern. Restarting it immediately will almost always have it going straight into the rug pattern and staying that way, or doing nothing at all. In this I have no way to run tests, the little LEDs do odd or otherwise random things without any input from the auto/manual or advance buttons. I had an adapter and new style RAM chips for awhile and never put them in, so I decided to do that, but no change.

I started disconnecting boards unrequired for boot and checking for change. I have come to note that disconnecting the IO board from the CPU/RAM board eliminates the problem, it will boot, The attract mode comes on, high scores display, and I can run through all the tests (which all appear to test OK)

Upon arrival at the switch/button test, the thing goes crazy, spewing out noises and button presses including a bunch of "INVALID SWITCH". Note that this is with the IO board UNPLUGGED. If I get to the switch test and plug the IO board back in it will stop, and I can test the buttons as normal. But it will hang and the problems will start up again if I go back to the game. Unplugging again in switch test will cause it to go back into shooting off random inputs.

Any thoughts? Sorry for a the long message. Here is a video of the problem in question: (Just a note, My brother was going on about sucking at cooking bacon or something while I was recording, he says the F word at one point, so if it offends you, just turn the sound off)

[smartbomb2084]

I would be looking at the ribbon cable on the interface board on the interface board side--- not the plug to the CPU.

Here is where being a dumb parts changer like me comes in handy when you have a known good interface board like I do to test.

   

[megamanmk2]

I took the ribbon cable off the headers (the cable going from ROM board to cpu board), shot some DeOxit on the headers and put the cable back on, the plastic cap that holds the cable onto the headers is broken so it wont snap back on as well. The game played fine for the good 6 or so plays I did inbetween tending to making dinner. Left it running while I made dinner and it didn't do anything odd. Then I started a new game after dinner and the ship started flying up without pressing anything.

Let the game end by waiting around to be killed, went into the diag mode and back to switch test. Up was constantly being shown as well as another switch (Forget which one). Unplugged the IO board and instead of the game going crazy it just stayed the way it was. I figure if its registering inputs with the board unplugged its not the IO board.

Game never crashed though like it was doing, so thats a start!

[smartbomb2084]

Which I/O board does your game have C8353 or C8573?

Go to this awesome link to find out.   http://www.robotron-2084.co.uk/techwilliamshardwareid.html

I have a few I/O boards around I might be able to hook you up with one.  That broken connector has to be fixed.

[megamanmk2]

I have the C8573, later board. Has the 09614 etching after the 5772.


The piece that holds the ribbon cable to the headers is the one holding the gray ribbon cable to the ROM board. It stopped crashing after I pulled the cable off the headers (the ROM board cable) and sprayed the headers with DeOxit, and put the cable back on.

Now the only problem "seems" to be that the ship will act like the "up" switch is stuck after varying amounts of play. Once I was able to play it for maybe 15-20 minutes without issue, other times its a minute. =\

[smartbomb2084]

So, you are saying the ROM board AND the I/O board have had their ribbon cables removed?

[megamanmk2]

OOPS. No, I meant just the ROM board to CPU board. I edited the post to make it correct. The smaller ribbon cable from the IO board to CPU board is untouched.

[smartbomb2084]

You will have to replace your ROM board or solder on a new ribbon cable (if you can find one--- anyone know of a source for replacement ribbons?)

That cable is constantly causing problems on these games.  Another weak link in the chain are the single wipe ROM sockets themselves.

For now, it seems like your I/O board is okay, but the ROM board needs fixed first before we can make an accurate determination on it.

[smartbomb2084]

ribbon cables......

http://www.therealbobroberts.net/harn.html

http://www.quarterarcade.com/Game.aspx/10472

[megamanmk2]

Yeah, I replaced the decoder ROM sockets with dual wipe ones after finding(during my original problem) that many pins did not have continuity from the side of the chip to the board.

Thanks for the links man!