I have managed to bring a world cup back from the dead but have not been able to figure out a switch related issue.

quick list of what has been done:

rebuilt power supply
rebuilt and fixed MPU
went through driver board all appears to be working properly (40 pin, reflow, sockets, upgraded resistors etc.)
rebuilt sound card

game passes initial board test, will coin up and play; however the switch issue makes it impossible to play a full game.

I did go through the switch test and there are NO switches closed.

I also went through all of the switches and 4 of them do not register in switch test mode, whats weird is 2 of the switches that do not read are duplicate switches in series (the other 2 switches in the series read just fine).

The following switches in the switch matrix do not read:

22 (right switch)
23 (left switch)
13 left ball thrower
25 spinner

I have checked the wiring and all diodes and continuity back to the board and all is good. I even replaced the board connectors just to make sure and no luck.

Issues with game play:

out hole switch 14 reads in test mode but does not register a ball drain unless you also press left eject switch 9

Also Left and Right Ball thrower coils do not activate when a ball is in either pocket. All coils do work in test mode so I know the driver board is working.

I also verified that the 2j3 switch row inputs are not strobing and the 2j2 switch strobes are all strobing. Which should indicate a playfield problem?

I though for sure I would find a bad coil or short but no luck so far, Any ideas?

Thanks for any help you can offer !

Bump

Any ideas?

I checked the switch matrix via the board with a jumper and all 38 switches read just fine. Looks like I'm back to the playfield to try and figure it out.

I already went through most of the switches, so I will double check them and start looking at the grounds

I also noticed that the ball drain switch scores 2k the first time it is pressed and 5k each additional time you make the switch. And you also get points every time you use the flippers.

Thanks

Patrick

Its been a while since i have had 5 minutes to look at this. Spent some time on it again last night, I had already went through that tutorial before my original post, when I check the switches in test mode none are closed. For current to flow backwards through a shorted diode and make another switch more than one switch has to be closed. I also went through every switch last night and checked the diodes and also cleaned and adjusted every single one of them. All switches are working as they should now, (the four switches listed above are now working fine).

current symptoms lead to a shorted diode but the switch matrix shows no closed switches and when i am testing i am only making one switch at a time.

current symptoms

start a new game with a ball in the outhole and the left eject coil followed by the R ball thrower coil fire then the outhole coil fires the ball.
Switch 32 (top rollover) causes a ball drain then game will not kick a ball out of the outhole until you make switch 9 even when the ball is in the outhole
Switch 28 (super ball advance) fires the R Ball thrower which should be activated by Switch 16
Switch 36 (left inside ball advance) fires the outhole coil every time it is made

I double checked every switch for the associated coils that are firing when they are not supposed to and even replaced all of the diodes even though they tested good.

Also all coils fire properly in test mode one at a time.

not sure where to look next any ideas?

I tried that already, when i test in switch test mode only the switch that i make shows closed, no other switches. I even tried banging on the cabinet, bumping it and banging on the playfield to see if any switches make and nothing.

Correction to my earlier post, switch 32 does not cause a ball drain. I thought the machine was seeing a ball drain because everything goes dead. It is actually tilting when switch 32 is made during game play.

Is it possible this is a MPU issue and data lines are getting crossed some how?

It is obvious someone worked on the MPU board before i got it so there are a lot of unknowns.

has anyone ever experienced this before?

I just double checked and all columns have a strobe and all rows are held high. I went into test mode and confirmed no switches were made (removed ball from game). System 3 switch test mode shows the last switch made, if no switches are made it will not display anything. when I make a switch in test mode I expected a phantom switch to show after i make the switch but nothing. I have tried it at least 50 times and no change, I also left it in test mode for some time to see if a phantom switch would make but nothing (even bounced it around and banged on the playfield).

I also made switch 32 and probed the switch rows to try and figure out which Tilt is being made but the only row that strobes when switch 32 is made is row 8 which is the proper row for switch 32.

Switch 28 (super ball advance) fires the R Ball thrower which should be activated by Switch 16
Switch 36 (left inside ball advance) fires the outhole coil every time it is made which should be activated by Switch 14

Another phenomenon to mention, When a new game is started or switch 9 is made the 3 coils below always fire:

Left eject coil fires every time switch 9 is made (this is the proper switch to fire this coil)
Outhole coil fires every time switch 9 is made which should be activated by switch 14
right ball thrower fires every time switch 9 is made which should be activated by switch 16

Also wanted to Thank you for your help and input on this issue.

I do have a scope and pulled it out and blew the dust off it tonight. I have not used it in over 6 years so I have some relearning to do. It is plugged in and charging and i should have time this weekend to start probing around.

I agree everything points to a diode issue but I checked them 3x, and even replaced ones i though might contribute to the issue even though they all tested good.

i will start by probing the rows and columns to see if anything looks funny. If you have any suggestions other then that I'm all ears.

Wish me luck and Thanks Again!

well I have other problems now. Haven't had time to look at this in forever, life has been crazy lately. Any way fired it up to check it out tonight and now its completely dead. won't even get into test mode, symptoms change every time i remove and reseat the rom chips. Roms were in it when i bought it, the software was upgraded but the chips are old and looking rough (one of them still has gold legs). Board has had the scan bees replaced with sips and whoever changed them did a nice job.

Any one in the metro Detroit area of Michigan have a rom burner that can burn me some new roms?