I just tossed that on for a quick test, the 5 volt line looks rock solid. It didn't even twitch when the MPU threw up on itself this morning and that little display is pretty fast acting.

Hook up the Fluke when I get home and start doing some checking, I'm rather curious its biased on the left flipper.

With Seawitch it was rock solid but too many parts have changed out since then so almost like starting from scratch again, not to mention the Centaur harness could have some hidden issue itself.

Just need to break it down bit by bit.

Tonight going to look at A2-J3-9 which is the zero crossing 43 to the MPU. It runs uninterrupted from the rectifier board to the MPU connector. I'm going to be looking at the voltages at the A2 board itself and at the MPU.

The A2 board is new so a potential trouble spot as it is an unknown quantity. All the other coils don't seem to trouble the MPU board though so a low probability. So what is unique about the flippers that could be causing an issue? Stay tuned...

1) Ill disconnect the SB300 from the J5 connector and retest.
2) Not sure what is on the SDB regulator, its from Evil Kenevil if that is of any help.
3) The reboot was manual not automatic, I hit the reset button on the Weebly MPU after it crashed. Came right back up.
4) Won't be taking the step of reinstalling the Seawitch playfield until I'm done with harness modifications. Reinstalling Seawitch adds another layer of changes such as the MPU running at twice speed as well. I might be able to do that by this weekend, I have some connectors that need to be finalized and switches mounted.

Just so were clear- On the (weebly) MPU, if the zero crossing sags or is even removed it will cause the MPU to freeze? The reason I ask is this is very much looking like a crash event and it does not restart. Its acting very much like a bad CPU again but that was swapped out.

I'll take a close up when I get home, but from a machine that was in storage a long time and my buddy just shotgunned new boards into it rather then take chances. That battery damaged MPU board I have been picking at on the bench is from the same game.

MPU was LED was OUT at one point, like when the CPU was suspect.

I might tidy up the wiring by this weekend and for the hell of it swap the weebly MPU with an Alltek which illuminated the problem with Seawitch was the MPU, not any other of my work. Might help point in the direction I need to be looking.

Close up of regulator

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Very curious indeed!

Fired machine up, started game and hit right flipper several times. No problem.

Blocked EOS on left side and hit flipper button a few times, nothing. Verified hold coil was working by pushing flipper up.

Pulled block from EOS , hit left button twice and the machine went dead and the mpu rebooted itself.

Displays were dead.

When working the left flipper its notable the GI flickers more than the right side which almost doesn't flicker at all.

Also, does crash out with or without SB300 plugged in.

Playfield J2 connector lead. Centaur is plugged in, the .156 is for Seawitch. No adapter needed and a lot of Ballys use the same connector as Centaur.

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No bench meter.

The odds of two coils (one original, one a known good coil) causing the exact same problem are extremely low, though not out of the realm of possibility. Diodes are worth a shot and will be first on the list to try.

At the moment I'm going to put this particular problem on hold so I can finish up wiring in the cabinet. Once the wiring and side rails are complete then swapping the Seawitch playfield back in becomes a reasonable option for testing. Too many jumpers and such in play at the moment.

The game didn't burp once last night after initial tantrum or two, I'm really liking the gameplay and the voice call outs.

This morning I fired up the machine and on the first game it tripped out right away, dead displays.

After rebooting itself (I did nothing) when I went to start a game it kicked the ball out.. and all the other coils including flippers were dead. After draining and on the second ball however everything was normal!

Very strange. I'm most curious to get to the bottom of this.

Finishing the harness work and reinstalling the Seawitch playfield to reestablish baseline is looking better by the moment.

Suggestions for a meter or scope that will do what I need to do for recording events? Looking at bench meters, I'd rather get a scope as being more versatile for more needs.

I'm thinking something in line with working on 30 to 40 year old pinball machines, preferably portable so I can get right in on a machine with troubleshooting like I am now. Full size tablet sized would be ideal and I can always data log to a laptop.

Not a good night.

Replace the diodes on the left coil, swapped MPU with Alltek, swapped A2 board with factory Bally, unplugged all sound and aux boards and even swapped SDB board.

All for naught.

And as a final extended middle digit, one of the coil drivers failed on the Alltek SDB during gameplay.

On the final game with the Bally SDB back in place it had been off for awhile, I fired it up and about 2 minutes into a game hit a drop target, the knocker fired and all the lamps went out as it crashed again.

Off to bed. I'll toss Seawitch back in the weekend. I'm starting to suspect that someone retired this game for good reason.

How I'm feeling this morning.

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Really chafes my ass to be at this place but here we are.

Pulled Centaur out this morning, dropped Seawitch back in. Changed the settings on the MPU, cleared the audits...

Seawitch works perfect.

So Centaur playfield/harness apparently has some sort of problem, which really has my curiosity going now as it can be so random at times.

Not to mention what on the playfield could be taking the MPU down.

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Some good news here anyways.

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Teased the wiring for the flippers and outhole out of the harness, nothing. So far going over the playfield all I have found was a nick in the wiring for the left sling lamp not near anything and a switch lug folded over on a bracket. Clearly not grounded as the switch was functional.

I'm going to solder the wiring back in place but have it as a seperate harness for now.

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Thanks for the kind words, would not have made it this far without the excellent individuals on the board who share their experiences and knowledge.

Just found a cracked diode on the outhole while soldering the harness back in place, could not see it hiding in the hole it sits. Fingers crossed it's the culprit but I still have my eyes peeled for other sources of mischief.

May my journey here help and inspire others to persevere.

Video uploading.

Things to do before Centaur is fully operational (rolled over from previous page)

1) Add harness and lane change switch to cabinet (DONE)
2) TRIAC for GI flashing circuit (DONE)
3) Repair TRIAC connector for Centaur harness. (DONE)
4) Install Aux Driver board, wiring for power and MPU control.(DONE)
5) Install Squawk and Talk Board, power and control lines. Modify board jumpers for EPROMS, burn and install. (DONE)
6) Lower cabinet harness (slight switch strobe line difference between Stern and Bally for coin switches and tilt) toggle switch
7) Speaker wiring- Different between Bally and Stern and have to figure out how to manage that smoothly, toggle switch.
8) Extra strobe line (ST-5) for Centaur switch matrix, have to install bypass switch as line is used by SDB on some games. (DONE)
9) Clearance cabinet playfield support rails. (Maple obtained) temporary done to originals.
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More stuff to do.

10) Several switches need caps and I just ran out, doh!
11) Locate backglass controlled lamps, make light shields.
12) Add lane shift switch to left flipper button, convert flipper switch stack to Bally from DE.
13) Repair aux board so all lamps work (3 out)
14) Installed hinged backplain PCB board.

In regards to the "flipper and outhole harness"; it was separated from the main harness, any repaired areas which had been heat shrinked got a second layer of heatshrink in case there was a solder whisker poking through and was tie wrapped to the main harness following the original run. The outhole diode was changed out, my last cap went on the stand up for the right side drop target trip and all switches, lamps and coil lugs were closely examined for anything abnormal. EOS switches for the flippers were adjusted for good measure.

There is a switch at the speaker to toggle between the Bally feed or Stern feed. Each has it's own wiring and volume control.

I have no frame of reference having only played Centaur at Allentown, can't recall. Could always burn some eproms to test with a real -35 to see if it changes.

Quench do you think a bad diode connection on the outhole is enough to crash the MPU? It is an unusual setup run through the solenoid expander. A scope here would be interesting to see the induced voltage created.

Thank you for the feedback- To be honest I'm looking for something fairly simple to "just get the job done" I know anything overly complicated is just going to sit in a drawer unused or at best I'll use only one or two functions and ignore the rest.

I have been using Photoshop for decades now (same version as a matter of fact) and there are STILL a number of functions I have not mastered let alone explored for the simple fact I have not needed too. Just the way I'm wired and with a lot of different things on my plate, little time for extensive studies 50% of which I'll forget by the time I could put them into practice years later.

Already setup and moved along to next problem, 2 volume controls the least of my worries and planned for. I may or may not have an SB100 game installed in the future, best plan ahead.

Correct: The only issue I can say with certainty when I went over the playfield wiring was a broken diode connection at the outhole coil. Maybe vibration from flipper actuation was rattling the connection. Game played flawless last night after being reinstalled.

Edit: flawless aside from some stand ups not registering quick hits due to missing caps.

Ah, you are correct! Looking at the Centaur SDB schematic this is more clear.

Same as the right, little to no change.

I have nothing else to put my finger on. The only things found were the outhole diode and a nick in a slingshot lamp wire.

Spoke too soon; five games in this morning the gameplay stopped and the MPU rebooted itself. I have the head open so can clearly see the MPU led go through the cycle.

Nope.

No sound at all, playfield just went dark and everything goes dead till reboot is complete and then you are back in attract mode if the mpu isn't hard locked requiring a power cycle.

When the slam is activated it will go "no class human" and the game pauses till ball drains and it continues. You lose the ball in play.

I did notice the GI seemed to be flickering during flipper activation again. Tempted to bypass the TRIAC to see if related.

There is a slam switch on the bottom of the playfield is there not?

The regular tilt has not been setup yet for Bally, nor is there any slam switch on the door or cabinet.

Looking into the manual, you might be onto something.

It states slamming the machine causes feature lights to go out, the game goes dead and a time delay occurs. The game restarts with a power up tune and game over light, so clearly rebooted.

Very, very curious.

And the flipper wiring runs along that strobe line in the cabinet I think.

Well that line of thought was a dead end.

Strobe 1 is prewired but does not hook to anything yet and terminates in the lower cabinet as you see it. Just to be safe, I removed the wire from the MPU J3-3 connector in case there was some bizarre electrical noise on the line making the MPU angry. The other end of the slam switch chain is J3-16 which has never been populated.

Has not crashed once this afternoon, but I'm not about to hold my breath. Until the problem is found, it isn't fixed.

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MPU, SDB and A2 board have all been swapped.

Same results.

Works perfect with Seawitch.

I'm almost to the point I want to replace every diode on the playfield but there has been no real rhyme or reason to the problem aside from it seems main flipper related. Maybe. On at least one occasion it crashed after hitting a drop target but that was proceeded by a flipper strike.

1) Same power supply as Seawitch, swapped out SDB and it does the same thing. Perfect with Seawitch, not with Centaur.
2) No slam switch, wiring physically not there.
3) I'm leaning in this direction but at a loss for the moment as to what.

Played a few games this morning.. no problem at all crashing. Strobe 1 still out of connector.

After a game or two added caps to flipper switches for arc suppression. Figured it could not hurt and extend the life of the switches. Seawitch never faltered without them so no illusions this is a fix, just an upgrade.