Motordome Left Ball Save Gate Issue

jeff412

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I have a Bally Motordome pinball. I can't seem to get the left ball save gate to work. If I short the tab on it's transistor(Q9) to ground, it opens properly. I don't think this is a wiring or electrical problem. Does any one else have one of these and can you verify that the left gate does or does not work?

Thanks,
Jeff
 
Now that you've verified the wiring, coil, and power are good, let's check the drivers. Take a jumper lead from tip 26 and tap the banded end of D21, if it doesn't work Q9 is bad, if it does check D21 to see if it is open. If D21 is good ground pin 13 of U10, if it doesn't work then, U10 is bad....or you have lost some circuit continuity in there somewhere, although this is unlikely unless board work has been done in the past. If it works when you ground Pin 13 of U10 then it goes back to the next chip.
 
Thanks. I'll do that. I had read on another forum that this was a problem with MotorDome and they believed it to be a ROM programming bug, but like you said I should check the rest of the circuit, before I draw conclusions. Thanks for getting me back on track.

Jeff
 
Blitz,

Do you have an english copy of the manual or are you using another 6803 schematic. If you have the english version can I trouble you for a copy? I searched through the schematics that I have and I believe you were referring to grounding pin 13 of U18 and not U10? It is a CA3081 transistor array. I am stuck at work tonight, so I will have to wait until I get home to check it out.

Jeff
 
Ok. I was hopeful that there was an english version out there. I was using the German version and a copy of Strange Science. U18 appears to be good. Looks like the next chip up line is the PIA. I just put a brand new one in there, but I'll try another one tomorrow and see if that is the problem. I have two bright lights that aren't working as well and they feed from chip U14 which also feeds from that PIA(U7). Maybe that's the problem.

Jeff
 
Did you try grounding pin 14 of U7? That would check the continuity from U7 to U18. Was U7 socketed or did you need to desolder it? If you had to desolder it, check all 40 of the pins for continuity against the schematic. I always do that after a chip removal/socket install just to be sure.

Don't the bright lights have a seperate fuse board??
 
Fortunately U7 was socketed. I haven't looked at the schematics of the PIA itself, so, I wasn't sure which pin needed what signal in order to produce a low at 14. I did probe pin 14 and there was no signal (high or low) when there should be. So I know I'm not getting a Low out of it. I've got more PIA's. I'll just change it and see what happens.

The problem with the lights is not caused by the PIA. When I ground the base of Q21 and Q22, I don't get lights. However, the diodes and transistors test good. Must have a wiring problem with those.


Thanks for the help.

Jeff
 
Did you mean "ground the collector" the metal tab of Q21 and 22? You would need to apply TP26 to the base to test the transistor, or ground pins 3 and 16 of U20 to test the whole drive circuit after the PIA. Did you check the bright light fuses and bulbs with a meter?
 
You are absolutely correct. I grounded the collector. I did not test the bright light bulbs with a meter, but they appear brand new. I will test them tonight. All of the fuses are good unless there is a hidden one under the PF somewhere. They were tested with a meter.

Jeff
 
The PIA's are good. I tried 3 new ones just to be sure. Now I'm to either the 6803, Ram or Rom and the output on those are all 8-bit data lines. If I had a problem with one of those I believe I would see more than 1 solenoid not working. I'm beginning to think that the previous post I read about this being a programming bug may be true. Am I missing anything?

Jeff
 
Well, it sounds like you've proved that the circuit from the output of the PIA to the coil is good, and that the PIA's were swapped with good ones, so all that is left is the address/data buses, but like you said if they had a problem there would be many more issues with the game. After all of your excellent circuit tracing/troubleshooting, I think you are correct in assuming that it might be a programming error. Sorry, but I guess your first idea was the right one!

"I had read on another forum that this was a problem with MotorDome and they believed it to be a ROM programming bug,"
 
Ha Ha! I wouldn't say it was my excellent skills. I appreciate your assistance.

Thanks a bunch,

Jeff
 
Ok. Will do. Haven't figured out the bright lights yet. Took a day of vacation and going out to work on it now.

Jeff
 
The Atlantis print shows a board with about 15 fuses on it for the bright lights. Do you have continuity from there to the lamp socket? Is voltage present at the bulb? Without the machine to look at or the right print it gets tricky.......
 
I found the problem. It actually looks like these lights have never worked. They appear brand new and the wood around them is not burnt like the others. Anyway there is no continuity from the bulb back to Q21 and Q22. I found it when I tested the voltage at the collector on the transistors and got nothing. Would you just replace the wire or try and find the break? It's not anything obvious.

Jeff
 
New problem. UGH! I put new flippers in and played a game just to test everything and into my second ball all of the A and B phase lights quit working. Any ideas? I'm going to start going through those dang blurry schematics again. No fuses blown.

Jeff
 
I've got 11 VAC at all of the lights, so the problem has to be on the driver board. I changed out U8 since it seems to be the only thing all of the lights have in common. That didn't work. I doubt if U15, U16, and U17 all failed at the same time. Just when I was almost done too.:004_scry:


Jeff
 
Pages 4-6 thru 4-8 of the Atlantis schematic have a step by step Troubleshootig for the phase lamps.

For the bright lights follow the wire from the bright lights to the control board, tugging on it in the harness, until you find the loss of continuity.
 
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