Hello fellow pinsiders,
This is the first time I have posted here. I have an Evel Knievel pinball with a problem that I cannot isolate. I have a particular circuit that is not functioning properly. In the wiring diagram it shows that they are interconnected to each other. The outhole, left outlane, L & R feeder lanes & top bumper are involved. The switches are all normally open. I have checked continuity between the switches and the connector J2 and everything checks ok. The switches are not being seen by the MPU in test mode and in gameplay. All the boards are new except the Lamp driver board. I have replaced J2 connecter & pins. The diagram shows that the 70 wire common comes off J2. Everything else works on game. Any suggestions would be greatly appreciated.

Thanks, Fred

The connector J2 has been replaced and according to the schematic all communication goes thru that connector. I have read that this switch circuit is a matrix. This version is a 8 X 5 matrix. This sequence is a row of switches at the bottom of the schematic. I am not sure how to check this. Since this matrix is only 40 switches I will begin to check continuity with all the switches. Maybe a working circuit is affecting this particular line of switches. There are 5 different wires in columns feeding each of those switches so I will check those other pins off the connector. Thanks Bill for your input. Schematic reading and understanding is not my strongpoint.

I will try the jumper between pin 4 & 15. Presently changing connector J3 with new connector and pins. After that I will jumper and post here with results. If the L & R feeder lanes scores, what is it telling us? Is it that it is not the MPU. I was aware of the color coding and do have a chart on the schematics. Earlier today did go into the switch test and the display showed "0" so no closed switches. Just for the heck of it I checked all the diodes in the switch matrix and all checked ok. Thanks for your help Quench !

Hey Quench,
You won't believe this but your jumper did not add scoring. I assume this tells me that the problem is with the MPU. We had the old boards with corrosion damage and reinstalled them and was able to enter in the test's. Every switch in the matrix was working just fine. We are contacting the board manufacturer to get an exchange for a new MPU. Glad to know what's wrong ! Only frustrated that time was spent looking for the problem that came from something I expected to be the cure. Again thanks for your assistance Quench. May ask for help again one day. Have a Stern Stars that will get to shortly. If any problems arise I will post in this forum.

Fred

Will check the slam switch today. If it does not work I will try the 6821 swap. I will leave feedback here to let you know the results. I was a field technician for a couple of years in the early 1980's. Dealt with obvious problems on the field and maintenance. We carried repaired boards for easy swap out. Bad boards were tagged for board tech with symptoms. Thanks again for your Help !

Fred

Quench, Just wanted to let you know the 6821 swap did not work. I even tried with the 6821's off the original board. Will have to exchange boards. Hopefully no more issues.

Fred