Gentlemen:
When I encountered this vexing problem yesterday, I had no idea it was going to generate so much confusion. I was rather hoping it would be something simple that I had carelessly overlooked.
I now see that this is unlikely to be the case. Thank you all for your replies. I will continue working on the locomotive, bearing your comments in mind. If I am able to restore it to running condition -- or if I encounter new information -- I will post that information here.
Thank you again.
"The field coil should have one end connected to the motor's frame and therefore to the locomotive's frame. The other end of the field coil should be connected only to the wire which, if it were colored, would be green, whether at a terminal on the brush plate or otherwise. The "green" wire should go to one of the outside fingers in the set of four on the e-unit, the leftmost finger as viewed from the side of the circuit board where the wires are attached."
Bob Nelson
Wire the loco exactly as shown HERE and you should be good to go. All black wiring is fine, but the connections have to match. Under no circumstance should any field wire be connected to a brush connection unless you are trying to get it to run in one direction only.
Rob
carlb01464 One end of the field coil goes to the body of the motor and the other end goes to your "missing" center terminal. If that wire is connected to one of the brush terminals instead, there is absolutely no way that that motor will ever go in reverse. The only wires that are connected to the brush terminals are two from the e-unit. The third wire also goes to your "missing" center terminal.
One end of the field coil goes to the body of the motor and the other end goes to your "missing" center terminal. If that wire is connected to one of the brush terminals instead, there is absolutely no way that that motor will ever go in reverse. The only wires that are connected to the brush terminals are two from the e-unit. The third wire also goes to your "missing" center terminal.
O.K., I think I now understand how your motor is wired. The middle terminal has, apparently, been broken off some time in the past. The two wires that should go there are now soldered together. This should work O.K. That leaves the e-unit or some kind of mechanical binding as being the problem. To check out the motor, you should try removing it from the chassis while it is on your test track. Let the chassis of the motor touch the chassis of the engine, apply power and cycle through the e-unit. You might need a third hand to do this, though. If the motor is still not able to run in reverse, then the only thing that I can think of is a bad e-unit. Why it failed while you were cleaning the brush plate would be a mystery, though.
lionelsoni There seem to be some contradictions here: It was implied that formerly the locomotive ran in both directions and now runs only in the forward direction.
There seem to be some contradictions here: It was implied that formerly the locomotive ran in both directions and now runs only in the forward direction.
That is correct.
Yet no wires were disconnected: "...all three wires are still in place." But later, "There are no 'three wires.' There are two..."
Let me clarify. There are two connectors on the brushplate, and only two. Each of them is connected to the E-unit. To one of the wires is soldered a small lead from the field coil. I did not disconnect any wires until another poster suggested I switch them, which made no difference. All wires are now back in their original configuration. It still runs in only one direction. Does that help?
Perhaps it will help if I try to describe how the motor should be wired...
That is how it is wired. None of the wires are colored, so I can't say which of them should be green, blue or yellow, but you have accurately described the existing wiring on this locomotive. And yet it still runs only in one direction.
Before I cleaned the commutator it ran in both directions. Now it does not, and I have no idea why.
There seem to be some contradictions here: It was implied that formerly the locomotive ran in both directions and now runs only in the forward direction. Yet no wires were disconnected: "...all three wires are still in place." But later, "There are no 'three wires.' There are two..."
Perhaps it will help if I try to describe how the motor should be wired.
The field coil should have one end connected to the motor's frame and therefore to the locomotive's frame. The other end of the field coil should be connected only to the wire which, if it were colored, would be green, whether at a terminal on the brush plate or otherwise. The "green" wire should go to one of the outside fingers in the set of four on the e-unit, the leftmost finger as viewed from the side of the circuit board where the wires are attached.
One of the brushes (it doesn't matter which one) should be connected only to the wire which, if it were colored, would be blue (or perhaps yellow). The "blue" wire should go to the inner two fingers in the set of four (which two fingers are connected together at their base).
The other brush should be connected only to the wire which, if it were colored, would be yellow. The "yellow" wire should go to the two fingers in the set of two (which two fingers are also connected together at their base).
arkady I'll see what I can do. But let me be sure I'm understanding you correctly. Do you mean "the field coil is to be connect to the chassis ground and also to an outside finger on the E-unit?" Because although there aren't any green wires, that appears to be how it's connected now.
I'll see what I can do. But let me be sure I'm understanding you correctly. Do you mean "the field coil is to be connect to the chassis ground and also to an outside finger on the E-unit?" Because although there aren't any green wires, that appears to be how it's connected now.
It would sure be easier to help you if we could see exactly how your 681 is wired. The wiring you are describing was definitely changed by a previous owner.
By the way, I'd like to thank all of you who've taken the time to reply.
arkady There are no "three wires." There are two, and to one of the terminals is also soldered one end of a lead from the field coil...
There are no "three wires." There are two, and to one of the terminals is also soldered one end of a lead from the field coil...
That's the problem.
The field coil is to be connected to chassis ground and a green wire from an outside finger on the 671-209 4 finger contact assembly on the e-unit.
carlb01464 I'm really curious now. If there is no middle terminal, what are the three wires connected to?
I'm really curious now. If there is no middle terminal, what are the three wires connected to?
There are no "three wires." There are two, and to one of the terminals is also soldered one end of a lead from the field coil. As I said, this brushplate doesn't look anything at all like the illustration in the online Olsen instruction sheet from a 681. It doesn't even take the same kind of brushes. I don't discount the idea that some previous owner has put a nonstandard brushplate on it (what other brushplate would fit a 681 motor?), but since it's been running fine up to now, I find it all even more confusing.
Oh, and the brushplate is stamped "Lionel," even though I'm getting the idea that a 681 brushplate shouldn't look like this.
It sounds like you have some kind of miswiring. Was the engine able to go in reverse before you cleaned the brush plate?
Yes. I've had it since last October, and today was the first time it failed to reverse.
If everything is actually wired O.K., it definitely sounds like a problem with the e-unit as others have mentioned.
Hmmm... Then the consensus seems to be that it's a mechanical problem and can't be the E-unit...but it's definitely the E-unit. Now you can see why this locomotive with the strange brushplate is driving me up the wall with this weird problem I've never encountered before. I'm about ready to submit this 681 to Ghost Hunters.
One thing that I neglected to mention was that at one point I had it on the rails and was giving it power, cycling the E-unit. When it came to what should have been the reverse position, just to see what would happen, I boosted the power. The breaker tripped in my KW.
I've since had it on the workbench, putting it through its paces with a 1033, but I haven't tried that particular experiment again. Do E-units get shorts? I've never heard of such a thing before. But if it was the motor winding, I'd expect it wouldn't run at all, in any direction. And if it's the E-unit, what effect could cleaning the commutator possibly have had on it?
Anyone know a good exorcist?
Even if the motor or e-unit was miswired, there was one e-unit position that allowed the motor to run forward. When he swapped the two wires to the brushes, that same e-unit position should absolutely have caused the motor to run in the other direction--but it didn't. That is why I now doubt that the problem is electrical.
My present guess is that the motor is trying to run in reverse but is blocked by something. Since a commutator cleaning was involved, that seems a likely suspect. However, it could be something else, like a faulty thrust bearing. The armature of a motor whose shaft is a worm gear is pushed axially in opposite directions when running forward and in reverse. A faulty or improperly located thrust bearing, which is supposed to keep the armature from moving very far axially, may cause mechanical interference that occurs only in one direction.
arkady No, all three wires are still in place. And none of them are color-coded. And there's no middle motor terminal. For whatever reason, this brushplate doesn't look anything like the one in the Olsen diagram for the 681.
No, all three wires are still in place. And none of them are color-coded. And there's no middle motor terminal. For whatever reason, this brushplate doesn't look anything like the one in the Olsen diagram for the 681.
I'm really curious now. If there is no middle terminal, what are the three wires connected to? It sounds like you have some kind of miswiring. Was the engine able to go in reverse before you cleaned the brush plate? If everything is actually wired O.K., it definitely sounds like a problem with the e-unit as others have mentioned.
lionelsoni Actually, forget about the toothpicks. I think Rob's test establishes that the problem is mechanical. Can you try turning the armature with your finger to see whether it will go in both directions?
Actually, forget about the toothpicks. I think Rob's test establishes that the problem is mechanical. Can you try turning the armature with your finger to see whether it will go in both directions?
Yes, it will.
Maybe a brush is hanging up on a commutator segment.
Could be, although the armature turns freely enough in both directions, even when power is applied and the E-unit is in what should be the reverse position. I can't feel any mechanical obstruction anywhere.
Actually, forget about the toothpicks. I think Rob's test establishes that the problem is mechanical. Can you try turning the armature with your finger to see whether it will go in both directions? Maybe a brush is hanging up on a commutator segment.
lionelsoni Just in case it is an e-unit finger gone bad, can you poke each finger with something like a toothpick while the locomotive is in the state where it should be running in reverse.
Just in case it is an e-unit finger gone bad, can you poke each finger with something like a toothpick while the locomotive is in the state where it should be running in reverse.
That's a good idea. I'll try it tomorrow. I've packed everything up for the night, and I'll have to re-solder the motor leads back on before I can proceed any further (I removed them to test Rob's theory about switching the leads).
Aside from that, do you have a voltmeter?
Afraid not. Do you suspect a voltage loss somewhere?
lionelsoni Did you by any chance disconnect the wires from the brushplate? If so, there is a simple miswiring that could produce your symptoms. The green wire should be on the middle motor terminal. The other two, probably yellow, can go either way on the other two terminals.
Did you by any chance disconnect the wires from the brushplate? If so, there is a simple miswiring that could produce your symptoms. The green wire should be on the middle motor terminal. The other two, probably yellow, can go either way on the other two terminals.
ADCX Rob Switch the wires at the brushes. Does it now go only in reverse?
Switch the wires at the brushes. Does it now go only in reverse?
I did. No, it doesn't. Still forward-only.
Oh, and there is no reason for any lube to be anywhere near the brushes or commutator. There is simply nothing to lubricate there. No bearing, no bushing, no gear or axle.
I agree completely. But it seems the previous owner had other ideas.
Help!
My Lionel 681 was beginning to get a bit sluggish. I checked the commutator, and sure enough it was cruddy with lube. So I disassembled the locomotive, removed the brushplate, cleaned the commutator and brushes, and reassembled. It ran great. Except...
It won't run in reverse.
I've made the usual inspections: the E-unit cycles properly. All E-unit contact surfaces are clean. All fingers appear to be making proper contact with the drum, and none are worn through. None of the fingers are broken. No wires are missing/broken on the motor. The locomotive runs perfectly -- except that it will no longer go into reverse. When the E-unit cycles to the Reverse position, it simply hums, as if it were in neutral
I've watched the E-unit cycle, and the drum is rotating as it should. In fact, when I cleaned the commutator, I never touched the E-unit at all. Just to make certain, I sprayed the drum/finger area with contact cleaner, but it made no difference.
This is driving me up the wall. Anyone have any suggestions? Thanks in advance.
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