Gottlieb Genie (Gottlieb, 1979) not scoring correctly

[ramrod2]

I have some things on the Genie that are not scoring. All 3 white drop targets do not score and also the 2 outlane 10,000 point rollovers do not score. Yes, the switches are adjusted and clean (with dollar bill). I found a trend with something in common with the switches that do not score, they all seem to be related on one common wire? SEE ATTACHMENT. I think it is a mpu problem (running original boards) but not 100% sure. I have ohm-ed out the wire in question but I do not see how one wire can be connecting all these things as they are supposed to score differently.... again see the attachment I hope it uploaded here ok. On the far right side of the schematic you can see they are all related on the wire 3-6-6 coming from A1J7 pin 10. I am very confused please help! Trying to keep game original and not spend $ on a Niwumpf board if I can help it

 

[pinballdaveh]

return line 7 that goes to pin 10 goes to ic Z28, its the ic just left of the battery. this ic is a SN7405N hex inverter. chances are that 1 of inverters that controls return line 7 is bad. installing a chip socket is good to do because it saves on solder heat to the new chip and makes replacing easy if ever needed again

 

[Coil_Smoke]

The computer is rapidly scanning the switch matrix looking for closed switches. This matrix looks like 5X7 . 5 Strobed rows with 7 Returns = a possible 35 switches. This makes for a economy of wire and connections. I guess that makes 12 wires instead of 70 interrogating those possible 35 playfield switches. A closed switch can be detected at the intersection of a row and column.That is how the same broken wire can disable more than one switch. If every switch is out in a column it does tend to indicate the above mentioned logic circuit problem. Your photo would be more helpful if we could see the entire matrix.What I'm getting at ... Use a jumper to complete the bad circuit on the board in the back box and see if logic for those switch locations is actually at fault. If you get those switches to indicate closed with the jumper go back and look for a bad connection/solder joint/broken wire somewhere else.

 

[ramrod2]

Well lookie here

First off, thank you for the replies. I'm sorry the pic only showed the affected side of the wiring schematic but that's all that would fit in my scanner (the game manual is large size). From the look of this picture, someone has already had problems with the aforementioned hex inverter. Luckily for me, looks like they installed a chip socket too! Obviously I will go over their socket installation job when I get the board back out of the machine and hope someone knew what they were doing. If only they had these available at a store so I could just go and get a new one and try it out. But noooo, had to get one online so it'll be a couple days until I mess with it again...