So, a friend of mine has a 1991 Williams Slugfest. The issue is that none of the outfield switches are working during gameplay or in test mode. This includes switches 41-47 and 61-63 and also switch 51 for rear ball trough.

All hits register only as foul balls. Switch 61-63 are only ones showing up in test report.

I have checked the following:
1. Continuity from switches 41-47 to Driver Board (OK)
2. Continuity from switch 51 to Driver Board (OK)
3. Switch Edge test - none of the aforementioned switches register. Test report only shows switches 61-63.
4. Checked all plugs at driver and mpu (OK)
5. Grounded flasher solenoids at Q38, 40 and 42. Nothing happened.
6. Inspected LM339 at both opto boards, all looks normal.
7. Ran tests for stuck playfield switches, all look good.
8. Checked all fuses, all are good.
9. Checked all wire harness connectors, all look good.
10. Checked for voltage at 41-47, all show 12 volts.
11. Rigged 51 closed and then it showed in test report.

What else am I missing? Any theories out there as to what could cause all of these to go down?

Thanks!!

I checked continuity from gr-yel wire on each switch 41-47 all the way to plug at driver board and all showed good. So, I feel confident that all the wires there are good.

The connectors all look good and the batteries have been removed from the board. Any other possibilities?

pinmike can I jump switches to the mpu 1 at a tine to see if there is a bad connection in there somewhere? I am out of ideas as far as what to try on this game...

Thanks.

So, BigAl56 you are saying basically I take switch 61 Left Bleacher and jumper it directly to the mpu board and then run a switch edge test? Then repeat for 62 and 63? Am I understanding this correctly?

Ive never had to deal with a switch matrix problem before. I understand the basic concept but will take all the detailed help I can get!

Thanks!

@BigAl56, there is no J20 in the game. Is it possible this is a typo and should say J206-5? That would fit the description of a connector to the mpu with a green and black wire connected. Otherwise if there's a j-20 somewhere I can't find it anywhere in the game. Can I jump J206 pin 5 to J207 pin 5? Does that eliminate playfield as a suspect?

Update! So, I turned on the game and removed plugs J 206 207 208 and 209. There is no J212 plug on this game fyi. And then entered switch levels test mode and put a clip on pin one j209. At the other end I used a 1n 4004 diode and touched each pin individually on j207. All pins registered except for pin 4. By no coincidence this is associated with the switches that were not working in the game and indicates bad u20 chip!! Eeesh what a runaround to find that little guy... Ordering tonight, will update after new chip is installed! Thanks for all the help guys!!!!