Most problems like this are “created” meaning someone has done something and caused it. Couple questions
-Did you recently purchase the machine and just noticed the problem?
-What was done recently to the machine if anything?

Often times I fine that a problem is created and it goes unnoticed for a period of time, then through the process of elimination you can find it. In my experience I think you have either a diode orientation problem or switch wiring orientation. I have seen very similar problems in the past. I had a Funhouse years ago doing the same thing, the operator had replaced a target with a “generic” and the diode/leg orientation was different. Problem only showed up when the center trough switch was opened in game play due to multi ball. Take a real hard look around all the switches in that row for any “pecker” trails of solder, sloppy work, etc. Feel free to Pm me with any questions.

Scott

Repin the molex connectors associated with the switches. Have you verified power at the optos? Is the voltage changing if the beam is broken? Broken wires are the last thing to id and find.

Very interesting problems.

Analysing the matrix, I would look into Right outlane, Bookcase closed and Grave A switches.

Do not test the diode directly. Put meter in diode test but put test probes on the white and green leads solder points. Should measure diode voltage with positive on white and switch closed. Otherwise (positive on green as well as switch open) "open circuit" like when the meter is not connected. Do it with either the row or the column connecter removed (CPU board).

The reason for testing this is to test not only that the diode is working. But also that the switch is correctly wired up.

A strongly suspect the Grave A to be bypassing the diode.

Is no 2 problem depended on whether the coin door or the bookcase is open/closed.

The no 1 problem could be the ULN2803 switch column driver IC gone weak.

If the 2803 was weak, it wouuld have shown in the game he swapped boards with. He can always confirm this again by re-swapping boards. He can also use the logic probe on the 2803 to see what the chip is doing logic wise. Read this link for info in testing the circuit.

https://pinside.com/pinball/forum/topic/terrybs-guide-to-logic-probes

Make this tool to test bad switch diodes..
https://www.pinwiki.com/wiki/index.php?title=Leon_Borre_WPC_Shorted_Switch_Diode

You probably have a switch lug touching something metal or bent over touching another switch lug. Another issue can be a switch wire rubbed through the insulation on some metal bracket under the playfield somewhere.

I typically remove the green center wire on each switch one at a time until the problem goes away. Then you know where the problem is.

Sounds like you haven't swapped driver boards, so take a step back and check your +12Vdc on your driver board for any AC voltage. Check at J116 or 118.

I had a similar switch problem on a Roadshow that drove me nuts. Discovered it was a cracked trace between BR5 & C30.

Good Luck!

I have just verified my theory. All you troubles ARE due to the Grave A switch bypassing the diode.

So if the diode measures correctly, it is the switch wired incorrectly. Or lugs bend and shorting.

Most likely due to the diode on the switch backwards, or the row wires soldered to the wrong end of the diode, therefore meaning the diode isnt being used.

Seen similar issues on other games because of this many times, even some switches that look to have been factory soldered wrongly.

I had a weird issue with a switch matrix on a DE MNF and I found that one switch wire was soldered to the wrong end of the diode. I had looked at it probably a dozen times before I realized what was wrong. See more information here:

https://pinside.com/pinball/forum/topic/tech-de-monday-night-football-switch-matrix-issue

I don't know, buy a new TAF. Go ahead and paypal me the $100

All sound advice. I'm not in the running for the cash because these have already been offered but I highly suspect a bad diode on the row.

1. Inspect each switch. Make sure wiring is consistent and diode is in correct direction. Look for non-factory type soldering (operator or previous owner repair). Most of these operators are hacks that just want the game up and running. They don't give a shit about performance.
2. Remove the A switch from the matrix. Problem go away? If not, work your way down the line. Better to remove one at a time then all at once. I would exclude removing the opto for now. Most likely a symptom of a diode on a microswitch down the line.

Thanks. But, reversing the diode is not the problem. The problem is that the diode is shorted - or bypassed. The latter meaning that the switch itself has a short internally. Or the diode is bypassed due incorrect wirering.

Trust me. When you replace these leaf switches, the replacement one is not always construct the same way in terms of what blade in the blade/insulation stack that is what. Which of them is the neutral one where the diode is soldered to a wire.

Finally. The insulation may crack and have the blades shorting. Can be via the wood screws.

I made this video demonstrating the consequence of bypassing the diode. The proof.

So I guess my “buy a new TAF” advice didn’t work?

I do not think a reward is what made people assist you. People a generally pretty helpful. But sometimes topics on the forum drown and is not seen by the right people.

Now the evidence is on film, I might turned this into a proper instruction video on these ghost switches.

Please do. Thank you!

Excellent thank you! Will pm you now. I'm glad we helped fix your problem. I will use the cash to help develop more pinball products

Jim

I think I was the first to point this out. Check my post “diode orientation”

What he ^^^^^^^said.

These "diode orientation" shots from the hip really baffles me.

Please try and reverse a switch diode and tell us what the result is.

It’s fixed...

C5204E25-6267-42B2-9856-9429E9D16C70.gif

I really don't understand why you think a reversed diode won't cause havoc on the switch matrix. I recently got a Last Action Hero (different manufacturer but same switch matrix design) that had all sorts of craziness. I tracked the issue down to two reversed diodes on two different switches. Having a diode on backwards can backfeed the signal through the matrix and cause phantom switch hits, which is exactly what the OP was experiencing...

Thanks,
Kevin

I could have swore I asked you to check the the diodes on switch 86 and 82 five days ago.
https://pinside.com/pinball/forum/topic/addams-family-multiple-switches-tripping#post-5515104

at least you finely got it fixed.

Giving it back to the community...