I am attempting to bring an OXO back from the dead and am making progress. This is my first really big dive into em repair so I'm still learning to decipher the schematics. I hope you all can help!

There are several issues but the one currently bothering me is the left O and X the top six roll overs do not register and the same with the left and right roll overs (left and right of middle row in the tic-tac-toe grid). The top O and X do not seem to register anything at all, while the left and right in the middle rollovers do activate the left and right roll over relays but not the corresponding relays on the long relay bank. Sorry if this is confusing!

Switches have been cleaned and gapped. I tried tracing the wires and checking continuity but probably doing it wrong. Any help is GREATLY appreciated!

Thanks for the detailed information. Jones plugs are cleaned and seated solidly, both in the head and bottom cabinet.

Switches for 2, 3, 5, 7 and 9 are working.

If I hit the 4 and 6 switches I hear their relays click but it doesn’t score or light up the tic tac toe board. But after those are hit and I then hit the 7 and 9 switches, the the 4, 7 and 6, 9 light up. Likewise if I hit the 7 switch first and then the 4 switch, the 7 would light and score but not the 4.

I did discover that the Match Unit coil is dead so the unit isn’t stepping up. Would this affect these switches?

I cleaned all the score reels and stepper units and went through all the switches. Same with the large bank of switches. There’s a lot and could have made some errors.

The trouble I’m having is the problem switches are not firing the corresponding Relay Bank switches.

X and o are not alternating. That was another issue I was going to tackle later!

Neither the top left o or x rollovers trip the big relay bank.

Thank you for all the great explanations and diagrams. If I manually trip the 1-x or the 1-o relay it lights but doesn’t score. But after, they do score if the switch is rolled over. So the coil is not being activated for these two switches.

When rolled over, the other four top switches do trip their corresponding relays.

Using the coil resistance chart

https://flippers.com/coil-resistance.html

I checked the resistance of the coils for 1-x and 1-o on the relay bank and they seem to be ok.

Yes, switch 1 is for the 1-o and 1-x.
So the switch should first score 1000 points and then, if unoccupied, light the left corner?

Still trying to wrap my head around this. Appreciate the help!

Yes, for the four working rollovers.

Correct.

Scoring never happens for the 1-o and 1-x unless I manually trip their relay on the large bank and then roll over their switch.

I will dig around a bit more and see what I can find. Again, your comments are invaluable!

Solved! I used a multimeter with safety pins attached to the leads to search for continuity. Looking at the schematics I knew the BR-Y wire was common to the all the top rollover switches and some worked so it must be the connection common only to the 1-O and 1-X switches. The R-BLU wire was only common wire to the two problem switches and they traced back to the large relay bank (see picture)

Turns out that Make Break contacts on the 1-O and 1-X relay bank needed to be cleaned and gapped better. You think you did it but you never know until you trace the problem.

So using the same logic for the other problem switches I cleaned and gapped those relays and now all the switches seem to be working. I’ll test some more but it is looking promising! I know I need a new coil for the match unit. Thanks for all the help, especially @steviechs. I hope I don’t need to but I might post more problems to be solved if I run into a brick wall. Thanks again!!

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Thanks for the help. All rollover switches are scoring and lighting the board correctly, for all four players.

The medium chime doesn’t activate but the coil just vibrates slightly. Is that a bad coil?

My next issue is a new coil for the Match Unit (the O and X selection light doesn’t alternate).

Here’s a picture of the project. Might need a little paint touch up on the cabinet!

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I checked the resistance of the chime coils (unsoldered wires). I didn’t see them in the coil resistance chart but they were all around 11.7, 11.8 and 11.9, so probably ok?

I also triggered a pop bumper that should chime the medium chime and saw that the chime’s plunger does indeed move but weakly. Maybe I’ll try swapping coils.

The paint job is a head scratcher!
I did clean the sleeves and plunger and all three move freely.

Wires to coil were soldered and they looked old so they were probably from the factory.

I believed it’s the 10 pt. relay that fires the middle chime. The left and right pop bumpers start at 10 pts. and should ring the middle chime but doesn’t. But when it is lit it becomes 100 pts. and it rings the other chime. I’ll try cleaning the 10 pt. relay switches again.

None of the 10 pt. switches ring the chime. Manually hitting the 10 pt. relay doesn’t ring the chime.

Update: after tapping some 10 pt. switches for testing, the 15 amp fuse blew. Probably a short somewhere? Could that short be robbing power to the chime coil? In the meantime I need to buy some 15 amp fuses.

Just used my finger to hit each switch.

I disconnected the playfield and pressed the 10 pt. relay and the medium chime does ring. It doesn’t with the playfield connected and the each time the relay fires the GI lights brighten.

Thanks. I think I’m going to worry about the chime after I replace the match unit coil.

So while trying cleaning some switches another issue has come up which is even worse than the chime problem. The machine adds games when starting a game and draining a ball. I noticed that the 25cent relay is always energized. Is that how it’s supposed to be?

So the 25 cent relay should not be constantly energized, correct?

So I fixed the issue of the 25 cent relay being constant energized. It appears that the coin unit had a short between two wires near the solder joint. That also fixed the issue of the pin adding games when starting a game and draining a ball.

So now back to the medium chime not sounding. I disconnected the chime unit and measure each of the coils’ resistance and all three were 11.7. But when connected to the pin the medium chime was 0.5 while the others were still 11.7. Does that mean there’s a short somewhere?

I just saw that on the schematic. Yes, the No. Match coil is toast. I am ordering a new coil and will see if that fixes the chime issue.

I was going to but the problems with the pin adding more games came up and I got side tracked. Then when that was resolved I forgot to switch the coils. But I do need to replace the No. Match coil.

Thanks. I’m hoping replacing the No. Match Unit coil will fix it. I do plan on repainting the cabinet. What an eye sore!

I found this picture from an older post https://pinside.com/pinball/forum/topic/oxo-change-relay-issue.

With a new coil for my Match Unit fixing (fingers crossed) the chime issue I hope not too many new problems come to the surface!

I think my biggest challenge is improving my understanding and the flow of the schematics.

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While I’m awaiting my parts order I looked at the Replay Unit and see that the nylon switch blade lifter is missing (yellow). What does the blue switch do?

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Parts and new coils arrived from PBR. After soldering in a new coil for the No. Match Unit the medium chime and the alternating X and O works. The new coil looks out of place!

Next issue: when playing a five ball game and the ball is on number 4, both ball 4 and 5 lights are lit.

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Found the problem. Loose Jones plug for the 3 or 5 ball play.

New issue (seems that they keep on spawning). When ball drains to the outhole the pin doesn’t score any bonuses and the ball doesn’t kick out to the shooter lane. I’m trying to read the schematic and was wondering if am I correct in the logic (see pic):

The ball closes the outhole switch (red). If there were bonus points scored, the bonus unit is not on the zero position thus causing the bonus relay to fire (yellow) and stepping down the bonus until it reaches its zero position. It then activates the outhole relay (blue) which activates the eject relay, dumping to ball into the shooter lane.

I’m still wrapping my head around the direction of the flow within the schematic.

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Cautiously optimistic. From the schematic I knew that Bonus Unit should activate when the ball drains onto the outhole switch. But it only activated when the Bonus Unit was in zero position (BLU-B). Cleaned and re-gapped the Bonus Unit switches, specifically the one connected to the outhole switch (Y-R) and the Bonus Unit Zero Position switch (Y-BLU, when the unit isn't in zero position). Looks like it’s working! Fingers crossed.

Looks like all issues have been fixed. A big thank you to all who had helped!

Playfield paint has been touched up and I made a playfield protector. It really smooths out the play especially with the slightly sunken inserts, but t’s a little weird having the ball roll so silently around. Now on to tearing it down to paint the cabinet.. Hopefully it still runs well when I put it back together.