Hello All,

I am fairly new to troubleshooting, would really appreciate some guidance on a machine I picked up a while back.

I have a Williams World Cup System 3 which to start I had all the boards serviced: MPU, Logic, Power and Sound. Here is what is happening with the machine now.

1. Power on the machine, displays will sometimes not come on if the ball is in the trough.
2. Power on the machine with no ball in the trough, displays always come on.
3. Sometimes boots to audit sometimes to game over.
4. When boot to game over, I am able to coin up and start a game.
5. Sound always triggers when game is turned on, sound only triggers 'sometimes' when game is started. If game does not start with a sound I will hear none during gameplay.
6. During gameplay, most times when the ball goes down the trough, the displays will go off and all actions stop, cannot use flippers etc. If the ball does go down the trough and it does not stop all, the kickout does not kick the ball out and start play to next ball.
7. Other targets on the playfield will also trigger all actions to stop, displays go out, no flippers.

Thank you pincoder I have been guided to use his romset to troubleshoot:

https://pinside.com/pinball/forum/topic/new-williams-system-6-in-game-test-roms

However I would like to bounce a couple questions off the group to ensure I am doing this properly, and since I am noobish.

1. I had the nvram installed on the MPU when I had this serviced, that being the case I believe I need the final rom to restore defaults to play after testing. I do believe I am missing that ROM, or is there a workaround for this?

2. I could use some direction on which roms get swapped to which roms on the MPU board to run through the tests.

Thank you all for your assistance, and I hope all of you are safe.

I have installed the first eprom chip and run the first test for 01a-leds. The top and bottom LEDs did alternate flashing as expected. I did monitor the flashing for about 4 minutes but did not witness a rate change. Perhaps I missed it or did not let the test run long enough. I'm posting a picture with the chip slot circled that I swapped for beginning the tests, in case another noob is wondering which slot to use.

test1 (resized).jpg

Thank you pincoder for the update.

Got through the next step with positive results again. I swapped out the 01a-leds eprom with the 03-CMOS chip. With the coin door open I powered up the pin and the top LED continually flashed which indicates the installed NVram installe is good i believe. I did also do a gentle wiggle on the chip and the results did not change. moving on to the next test