(Topic ID: 238030)

Baffling Globetrotters solenoid issue


By matfodtilt

11 months ago



Topic Stats

  • 15 posts
  • 6 Pinsiders participating
  • Latest reply 11 months ago by Eric_S
  • No one calls this topic a favorite

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#1 11 months ago

The game boots, plays, and scores. The problem is the drop targets won't reset and the target saucer related to the drop targets won't kick out the ball. They score points, so I'm guessing the MPU sees those units. They don't react to the solenoid test, but do reset and kick when I ground the transistor ground tab. I have an AllTek MPU and a completely rebuilt, and tested, original SDB in the game. These two solenoids are controlled by transistors 11 & 16 on the SDB. I have replaced every component in both of these circuits. The associated IC's have been replaced. The male pins have been re-flowed and most of the female connectors re-pinned. I have put two other circuit boards in the game and the problem remains. There is 43vdc at both coils and they are good. I am assuming the ground signal is the problem but I am not sure how to isolate the problem. I am about out of ideas, so I'm reaching out to the brain trust. Any, and all, suggestions will be greatly appreciated.

#2 11 months ago

Underfield fuse?

#3 11 months ago

Simulate the inputs of the solenoid decoder and see if you can get it to fire that way. (Jumper wires holding the inputs high and low, then a momentary ground to the solenoid select will simulate what the game does when it's firing a solenoid)

You sure the transistors are good? Grounding the tab doesn't test the transistor.

#4 11 months ago
Quoted from cody_chunn:

Underfield fuse?

All the other coils on the play field fire, but I changed the fuse holder and fuse just in case.

#5 11 months ago

Tested the transistors before I put them on. And you are correct, tab grounding was only mentioned to indicate that there was a clear path from the transistor to the coil. I have put in at least two other SDB's and gotten the same result. Very frustrating.

#6 11 months ago

Could be a problem with the sigal from the MPU to the SDB. Check easy things like continuity back to the MPU PIA and cold solder joints on connector header pins. Do any of the coils share a comm on upstream IC chip?

I was having random lamp issues and it turned out it was a bad 5101 RAM chip that still passed the start up test. I don't think that this is case here, but if all else fails....

#7 11 months ago

Some Joe Shadetree trouble shooting here.

Reading the blueprint on IPDB.org shows all solenoids are powered from a common wire. I just have not located the color of that common wire. On classic Sterns the common wire is yellow.

1) Get a jumper wire and jump from the common wire from a solenoid that is working to common wire of a dead solenoid to make sure you don’t have a break in your common wiring.

Or

2) I advise caution because if you do this wrong you can blow a fuse...

Unsolder or cut the return wire from the dead solenoid and then also cut the return wire from a working solenoid and jumper to the dead solenoid and see if that helps.

If this helps then there can be a problem with the board or a break in the wiring. So you will need to check continuity.

All you are trying to do is isolate where the problem might lie.

Again, DO NOT jump one return wire to another. You can only jump the common wire.

Also, the print shows the drops, the saucer, and the right outlane save gate to be on the same common wire. But the gate is upstream of the drops and saucer.

Hope this helps

#8 11 months ago
Quoted from Eric_S:

Could be a problem with the sigal from the MPU to the SDB. Check easy things like continuity back to the MPU PIA and cold solder joints on connector header pins. Do any of the coils share a comm on upstream IC chip?
I was having random lamp issues and it turned out it was a bad 5101 RAM chip that still passed the start up test. I don't think that this is case here, but if all else fails....

The game has a new AllTek ultimate mpu in it, on top of that I had another alltek mpu on hand which gave me the same results when I put it i the game. I replaced all of the female pins on the mpu and the sdb, and verified, with the schematic, that the connectors were pinned correctly.

#9 11 months ago
Quoted from cottonm4:

Some Joe Shadetree trouble shooting here.
Reading the blueprint on IPDB.org shows all solenoids are powered from a common wire. I just have not located the color of that common wire. On classic Sterns the common wire is yellow.
1) Get a jumper wire and jump from the common wire from a solenoid that is working to common wire of a dead solenoid to make sure you don’t have a break in your common wiring.
Or
2) I advise caution because if you do this wrong you can blow a fuse...
Unsolder or cut the return wire from the dead solenoid and then also cut the return wire from a working solenoid and jumper to the dead solenoid and see if that helps.
If this helps then there can be a problem with the board or a break in the wiring. So you will need to check continuity.
All you are trying to do is isolate where the problem might lie.
Again, DO NOT jump one return wire to another. You can only jump the common wire.
Also, the print shows the drops, the saucer, and the right outlane save gate to be on the same common wire. But the gate is upstream of the drops and saucer.
Hope this helps

The common power wire is yellow and I have 44.7 vdc at both coils, my problem is in getting ground to those coils when the contact is made. If I ground the tab on the associated transistor, the coils fire. I appreciate all the effort, keep 'em coming.

#10 11 months ago
Quoted from matfodtilt:

The common power wire is yellow and I have 44.7 vdc at both coils, my problem is in getting ground to those coils when the contact is made. If I ground the tab on the associated transistor, the coils fire. I appreciate all the effort, keep 'em coming.

Then try this: Remove the return wire from the wafer connector at J-1 or J-whatever at your MPU. Then put a connector pin on a jump wire and put that to replace the wire you just pulled. Clip the jumper “return” wire to the solenoid and see if bypassing the play field wire changes things.

You will not need to remove the return wire at the solenoid. Just make sure the in-pinned end cannot short on something.

Good luck.

#11 11 months ago
Quoted from matfodtilt:

The game has a new AllTek ultimate mpu in it, on top of that I had another alltek mpu on hand which gave me the same results when I put it i the game. I replaced all of the female pins on the mpu and the sdb, and verified, with the schematic, that the connectors were pinned correctly.

I would still suggest testing continuity between the MPU and SDB and checking very carefully that the wires were put into the correct position in the connector. If a connector crimp wasn't good or off by one position, the signal from the MPU to SDB may not be reaching. I once had a problem where a wire broke inside the insulation and doing a continuity check was the only way I found it.

#12 11 months ago

Have you tried cleaning or replacing the coil sleeves. Do they move freely?

#13 11 months ago
Quoted from cottonm4:

Then try this: Remove the return wire from the wafer connector at J-1 or J-whatever at your MPU. Then put a connector pin on a jump wire and put that to replace the wire you just pulled. Clip the jumper “return” wire to the solenoid and see if bypassing the play field wire changes things.
You will not need to remove the return wire at the solenoid. Just make sure the in-pinned end cannot short on something.
Good luck.

Earlier, I had bypassed all the game wiring to no avail. Found the problem though, a new U2 socket was bad. I'll start continuity testing them before mounting from now on. Thanks to all.

#14 11 months ago
Quoted from matfodtilt:

Earlier, I had bypassed all the game wiring to no avail. Found the problem though, a new U2 socket was bad. I'll start continuity testing them before mounting from now on. Thanks to all.

Thanks for posting the solution. It is always nice to know what was going on.

#15 11 months ago

Which board had a bad U2? I would have thought swapping MPUs and SDBs would have revealed the board issue.

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