Alright fathom tech people.. this one has me stumped.
If I'm in a multi player game, sometimes the game will flip to the next player mid game with no drain. I suspect a though switch..
The other issue is in the green inline drop target section. It seems the 3rd drop gets triggered without being hit and kicks out the ball to be stuck behind the up drop targets.
I've replace damn near every switch diode.
The capacitors on the switches that take them I have replaced, but that seems to make things worse.
Someone please give me something else to try.

Also, sometimes it will add a player during the first ball. Yes I changed the diode on the start button.

This happens with an alltek mpu as well.

I currently have the original mpu in there with the most updated roms from John Wart.
I can put the alltek back in if that helps diagnose problems...

Thanks for the insights! I will run through the switch test with the apron off to verify the mpu is seeing these. I suspect something is up with switch #3, since it has one micro-switch and one leaf switch tied together.

I think I repined the solenoid expander board connector... but I'll double check, then reflow male pins. I didn't know that bulb did anything.. Just thought it was some alternative to a resistor or something.

I checked the through switches and they all function correctly in the switch test.
I replaced all the diodes associated with those switches anyway.

I checked the solenoid expander board. I did reflow and repin that connector.
The bulb was burnt out, so I replaced that. (Still not sure it's function)

Then, I also repined the plug going to the coin door, thinking this was contributing to adding players and jumping to the next player mid ball.

After all that, the green drops seem to be worse. I hear the sound for when a drop is spotted, but I didn't hit anything. Eventually it makes it up to the third drop and then the ball kicks out and is stuck behind up targets.

I still get extra players added on ball one.

I have also seen it jump to the next player mid ball.

Any other suggestions?

Thanks! All solder is good on the bottom of the board. I put in a fresh incandescent bulb, however I suspect the socket is flaky; so I'll probably just replace it for a good connection.

This functions as it should.

Done.

While checking this I think I found a suspect diode. This is probably the cause of the extra players being added during ball 1.

These register in the switch test fine. I don't think they are connected to the drops or kicker at all; so these are probably non essential switches..

No: When it flips to the next player, the drops don't reset. It just does its cycling of insert lights (like right after it says "fathom" on startup), then it keeps going but scores on the next player now.

Going through all the switches: I did notice that on the switch table vs. the switch matrix; coin#3 right is supposed to be switch 9, but blinks as switch 1 Outhole. Coin#1 left is supposed to be switch 10, but blinks as switch 2 - #1 left of outhole. Coin#2 middle is supposed to be switch 11, but blinks as switch 3 - #2 left and #1 right of outhole.
The matrix says these coin switches are supposed to have diodes, but non of my other bally's have these...

I did all of this in the hour I had at lunch, so I haven't tested yet.

All connectors in the back box are new housing with new pins.

Ok. I play tested it and tried to make it show errors.
I think the issue of adding extra players on ball one is fixed. I think it was a bad diode on the cave trap saucer, because that switch is right next to the start button switch in the matrix.

It did flip the game over to the next player-mid ball once, but it's very random. I noticed it happened when the ball was very active in the pops...

The green drop targets are still giving me problems. If you run through the sequence of physically dropping or spotting, it functions fine.
Something is causing the switches on the drops to falsely read, but not drop. Eventually the locked ball kicks out to up targets.
I tried hitting a bunch of switches to make it falsely read, but i can't find a pattern.

Another thing I noticed is that when multiball is activated, if a ball is hit back into the saucer, it doesn't reset the drops.
Maybe I have some dip settings messed up? It would be great to get a pic of someone's settings who's game plays without errors.

Also, I put a new socket and bulb next to the solenoid expander board. Not sure if this helped, but it's done.

bump

Any suggestions on what to look at next would be much appreciated..

Thanks for the explanation.

The game functions kind like this, but it's like you hear the spot sound "Aah" as if you hit 3 greens on the left bank, but it doesn't drop any targets in the in-line green drops.

All drop target banks were ultrasonic cleaned during the restoration.

Thanks for the settings! I confirmed the jumpers are correct. 2732s at U2 and U6: 4-13a, 7-8, 10-11, 12-GND, 16a-29, 31-32, 33-35
No change.

Attached the switch matrix with switch numbers added for reference.

I have more diodes and capacitors on order. Thus far, i've used 1n4001 diodes and 0.1uf Caps. Ordered 1n4007 diodes and 0.05uf Caps to see if that makes a difference.

fathom switch matrix (resized).jpg

switch numbers (resized).jpg

I'm still plugging away. No solutions yet though...
I tried swapping boards for everything, one at a time with no change.
All symptoms point back to switch capacitors. I replaced all caps with some 0.1uf ceramic caps; but the manual says to use 0.05uf caps. The manual also says to use 1n4148 diodes. I'm not sure if this matters but, i have been using 1n4001 for replacement thus far.

If i'm doing something wrong or not doing something in my troubleshooting; please speak up. I'm open to suggestions.

This has got to be it! The only connectors I didn't replace with Molex were the lamp boards.
Stumbled on this in Clay's repair archives.

Repair# 609 for Eight Ball Deluxe. (Not the same game, but the concept is the same with the drops on fathom)
Now the Solenoid Expander board’s state is controlled by a lamp driver SCR (Silicon Controlled Rectifier.) Why? Well remember this whole issue came about because of a lack of Solenoid Driver board transistors, so you don’t want to use a SDB transistor to control the Expander board. Instead they used a lamp driver SCR. In order to accomplish this, there’s a #555 light bulb next to the Solenoid Expander board, which acts as a load for the lamp driver SCR.

I know, it’s a bit confusing. But to put it in other terms, this whole concept is much like what Williams did on system11 games. Williams used a relay so one transistor could control say a coil and a flash lamp. Depending on the state of their A/C relay, either the coil or the flash lamp would be activated by a single driver transistor.

So what this game was doing was at game start, instead of kicking the ball from the outhole to the shooter lane, the #1 drop target would auto-drop. This happened because the Solenoid Expander board’s relay was in the wrong state at game start.

The fix here was all related to the IDC (insulation displacement) connectors. These these don’t wear well over time, and often need to be replaced. In addition, someone previously tried to “fix” some of the connectors by soldering wires directly to the connector male pins. So it was obvious some work needed to be done.

To confirm this, if I put pressure on the connectors, the Solenoid Expander board would start to work. (The easiest way to test the Solenoid Expander board is to just put the game into lamp test. Then the Expander board will “click” on and off, and its associated #555 lamp should flash.) With the Expander board not working, the game would activate the right driver board transistor, but that in turn would activate the wrong coil (based on the Expander board’s state.)

Repinned all the lamp board connectors. No change.

I finally figured this out!!

It wasn’t the solenoid expander board. I put in another one from a different game with no change.

I finally got my new 0.05uf capacitors in and 1n4007 diodes. I started with the switches that had capacitors and replaced them with new. Then play tested.

The issue was still there; BUT I found some consistency. I noticed when targets were down on the 123 bank then the green targets started activating when other switches were hit. So, I looked closer. The problem was when #2 was down. Consistently, left pop bumper triggered 1st green drop, bottom pop triggered 2nd green target, and right pop triggered 3rd green target. None of this physically spotted/dropped a target, so when the 3rd green was triggered the ball in the captive hole would kick out to up targets.

Took my multimeter to the diode on that #2 drop switch; and sure enough; shorted. Replaced all those. Play tested. No change???

Tested again, still shorted. Removed the diode on #2 and tested that to see it was fine.

Turns out, way back when I was populating the underside of the playfield during the restore; that switch fell apart. I put it back together, but missed a spacer between two of the switch leads; so it acted like the diode was shorted.

I drew on the switch matrix to represent what was happening: With drop #2 down, that sent power down the red path. Then when a pop was hit on the green path; it would back-feed through and trigger a green target. This is likely why the problem was worse when the capacitors were installed on the pop switches.

Looks like everything is fully working now; so I'll call this one solved.
Now I just need to upgrade/modify those pesky linear flippers....

fathom switch matrix problem (resized).jpg