Sorry for not posting a reply earlier, but work & other insignificant things get in the way and this ended up being back-burnered… Also, I went off into the desert on my own to look at this again…Here’s what I discovered: the two (2) engines that I have, the 204 and the 1684 have the same wiring configuration, i.e., one wire goes from the collector to the field and the other wire goes from the field to one of the brushes, or to put it another way, one of the brushes is grounded. I got the 1684’s motor to work! But here’s the rub…I could only get it to work if I took one wire from the transformer and touched the collector on the bottom and touched the other wire to the brush that was NOT grounded. If I took that wire and rubbed it against a wheel, any wheel, NOTHING… no spark, no hum, nothing. I suspect this means that I have an open field somewhere on the frame…or it could be that I making that up.
Engine #2…the 204: this I could NOT get to work, when I applied juice to the motor the same way as described above, got hum and that’s it…however, the field winding got very hot…is it possible the field winding is bad? Or, to put it another way, what else could cause this?
Thanks again for any guidance you guys…and especially Bob…can give me.
From your last description, I think that the 1684 has a field wire connected to the wrong brush. Try moving it to the other brush. Then you will have one field wire connected to the pickup (as now), the other field wire connected to the ungrounded brush, and the other brush connected to the locomotive frame. So putting voltage between the pickup and the frame should supply current to the armature and the field in series, and the locomotive should run on the track.
For the 204, check your field winding and each of the brush holders to see which if any of them has any connection to the frame. Then we can see whether there is a sensible way to hook everything up.
Thanks for the VERY quick reply. Ok, since my last post I’ve gotten both motors running, but they are both doing the same thing regarding applying power to the wheel(s) and the collector. Nothing…zip… but both motors work just fine when power is applied as per my last post. I am trying to understand what you are saying about moving the field wire to the other brush…If I do that, aren’t I just switching which brush is grounded? How does that affect the frame becoming grounded? I’ll try it, but I am having a hard time wrapping my head around this…unless I switch the field wire connections…? Does that make sense?
To rephrase my question, how does the GROUNDED brush get connected to the frame? By default, isn’t whatever brush that’s NOT wired grounded? So either brush could function as a ground, right?
Ok, I rewired it so the field wire is going to the OTHER brush. Same thing, no go. Works just fine when I apply power to the pickup and the unwired brush, but no go when I put power to the pickup and wheels…there is something else going on here.
The brusholder without any wires attached should have a tab attached that extends over to the brushplate screw on that side. The brushplate screw should have an internal toothed lockwasher under the head. The lockwasher should make firm contact with that metal tab. This is the source of the “ground” I have seen some brusholders with that tab damaged.
Now it seems that neither brush is “grounded”. Please do what I asked for before, disconnect the field of each locomotive from any brush that it is connected to and remove the brushes themselves. Then find whether and which of the brush holders and fields is connected to anything else, particularly the locomotive frame. After we get that inventory, we can continue with the debugging.
Ok…IT WORKS! CW, want to say thanks on the tab suggestion. That was the problem. Wasn’t grounded between the brush plate & the frame…that did it. Works like a charm now… Bob, thanks for all of your help getting me to that point…could not have done it without and I learned A LOT…Much appreciated.
Ok guys…next project…when I hook up the 1684’s E-unit…nothing. pretty sure my wiring is correct and solid. But no response from the motor. If the drum is not making good contact with the fingers, could that cause this?