Williams Demolition Man Slingshot and Popper Problem

[FIXNWILLIAMS]

I have a Demolition Man Pin and the other day my slingshots left, right, upper, and pop bumpers quit working. I pulled the glass off and captured the ball to force it into a ball search to see if the solenoids had power. They do, they all popped accordingly during ball search mode. I then bounced the ball off each slingshot and popper and no reaction.

I have now concluded that there is a switch problem. The service manual had a chart showing column and row. It looks like they share something common in the circuit? So I am wondering could this be a fuse? I looked at all the ones I could find and they appeared not to be blown. Maybe a ground on a connector on the driver board? Also does anyone know if this is a driver board issue? If so is it worth fixing, or should I just get a replacement from rottendog?

Also it may be worth mentioning I replaced the 11 pin connector for the GI as I lost a string, the connector was quite crispy. New connector = problem gone. Thanks to anyone who can help!

[spalmer]

Problem is likely U20 on the CPU board. Check for battery corrosion in that area. If it looks good. I would try replaceing that chip. Switch Columns are controlled by this chip. Again this is on the CPU board not the driver board. Also check check to Green wire with the yellow strip at connector j207 pin #4.

Another way to see if you have a board problem or problems elsewhere you would need

1. A jumper with aligator clips on both ends. (available at radio shack)
2. a diode. also available at radio shack.


Place the game into the switch level test on the menu. Remove connector j207 and j205 from the driver board. Connect one end of the jumper to pin 4 or j207. Next connect the other end of the jumper to the non banded end of the diode. Next touch the other end of the diode (the banded end) to the pins on j205 starting at pin 1. If the test shows you are closing switches, it is not a board problem.

[FIXNWILLIAMS]

Is this part game specific? Meaning it's programmed? Or is it just a replacement part by number?

[spalmer]

It is not a programmed chip and not game specific. The chip is a ULN2803 and is a pretty common failure part. Have you completely ruled out the wiring.

[FIXNWILLIAMS]

Sweet, I ordered three of them for future Williams games I may own, or repair for someone else although I am a long way from repairing pins for people, at least for money anyway. I mostly want to keep it a hobby. I also saw a post somewhere in another forum where I guess U 14 is prone to fail also which makes sense where it is a socketed chip as well,so I ordered a couple of those too. It was cheap money to have them handy. I did not go through every inch of the wiring, I checked all the solder joints on all the leaf switches and they looked solid, I double checked the pop bumpers as I had them appart recently to replace the right popper bracket that was broken so I replaced both while I was in there and also found that both leafs were waaaaaay out of adjustment so I tightened up the gap on them and wow what a difference in gameplay! I have only been pinballing for a year but I have learned a lot. I have the advantage of experience with HVAC electronics and controls, so I do get how some things work in theory. It seems that with the solid state pins it's the same input output logic as HVAC controls more or less. Thanks for your help, I did'nt know what the hell was going on. But I will investigate further and trace al the wires end to end, in case theres a hidden cause of the chip failure. Also I should mention I did try to re-seat the plug on the CPU that has the switch inputs thinking maybe a corrosion issue was there, I also made sure the wires were still punched down well in the connector. Thanks a ton! I will post my results when I get my parts in the mail.

[FIXNWILLIAMS]

Thanks spalmer! Got the ULN2803 chip in the mail yesterday!
I pulled the old one, plugged in the new one and BING! I have all my pop bumpers and slingshots back!

Fixing pins is fun when you can find the problem or find a guy who knows whats wrong. Plus my wife is happy she loves this pin.

If it magicly dies again I will dig deeper and see if something else is causing it to fail and I will post all findings to share with the community, but for now we're back up and running. Thanks for replying to my post! Now I'm going to see if I can find some new or good used ramps, mine are pretty well cracked.

[spalmer]

Glad you are up and running. If it happens to die again, check and lights that are close to the switches on that column. If one of them has gotten bumped like during ball replacement and is shorting against the switch connector, it will blow this chip.

[FIXNWILLIAMS]

So thats what happened! I had a GI near the left slingshot that was dangling that I found when I went to investigate why the Poppers were not working, I re-installed the GI socket ( found the screw in the bottom of the pin cab ) while I was in there.

So Possibly I fixed the cause when I fixed the GI that I discovered on my way to see what was up with the solenoids. It all makes perfect sense! You really know your stuff Spalmer! Thanks for all the great knowledge!

[spalmer]

I am glad we solved the mystery!!