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I bought 2 Atlas SD38's off eBay last year. I tested them individually and they both run fine. However, when I put both of them on a track at the same time (DC), one runs fine and the other doesn't run at all. I can hear the engine but it doesn't move.
To me, what you describe doesn't sound like a short, but that is possible through the connection supplied by the couplers. Now, when you say one runs and the other doesn't, is this while they are coupled to each other? It could be that the polarity to one motor is reversed and one loco is pulling the other down the track, or it could be a short as described through the couplers.
If they are not coupled together, and one doesn't move but the motor is running, take the body off the chassis, and see if the universals are connected to the motor and the gear towers on the trucks. Also the grease in the trucks could have dried to the point to where one truck is "frozen", (can't turn). On locos that have not been run regularly, or in a long time, a teardown and a good cleaning and relube should always be done prior to running on a layout as regular power.
Even on locos that are run regularly, this procedure, the teardown etc, should be done at least once a year.
The locos are not coupled. As I said, when it's on the rails alone, it runs fine. When I put the other loco on the rails, the engine sounds like it's trying to turn but it won't move.
When you have the 1 engine on the track watch which way it runs. Then put the other engine on the rails & make sure the transformer is set for this engine to run the same way. If it runs the opposite way the trucks are reversed in that engine. That problem will cause a short if both engines try to run in opposite directions. Found this out the other day from 2 SD40-2's that I got off EBay.
Another problem you may encounter if someone put 2 front or 2 rear trucks in the same engine.
What scale are you working with? I don't remember any SD38 offered by Atlas in HO or N scale. I can't even remember any SD38 offered by any companmy, up 'till the last couple of years, and they are in HO scale (Kato and Athearn).
Now, I have an N scale Atlas SD24 that had that problem when I got it, and it turned out to be the little plastic bushings at the ends of the motor shafts had cracked, and were slipping on the shaft. I put a drop of CA on the bushings, and solved the problem. I've heard of many of these that have this trouble out of the box.
Bernie, those are SD-35's. The spotting feature is the small fan between the two large fans, just like the GP-35. Whoever advertised them as SD-38's was confused.
The difference between front trucks and rear trucks isn't always apparent but the wheels have to be insulated on the same side to not cause a short. A single engine can sometimes run with reversed trucks but puting another engine on the track will cause a short in the engine with reversed trucks. The first thing to do is pop off the shell of both engines and compare the insulated ends of the trucks with one another. It's usually a small piece of plastic on one end of the axle before the wheel. If they don't appear the same, you have a reversed truck and need to correct the situation.
At least it was an easy fix.
Those look like early Atlas/Roco engines, though Jim Conway bought the molds and had them built in Mexico for a while. I also remember seeing these, or very similar, in IHC boxes not long ago.
They were very good for their day, and still good today, even though the details aren't really up to today's standards. They're even easy to convert to DCC, the motors are isolated.
Actually my track is clean but the wheels were filthy. The only thing I didn't check when I tested it. Funny that it ran on the track solo but not in tandem with another engine. After I cleaned the wheels, it runs like a charm. Both are noisy but run great.
I repainted and renumbered them to a local road name: Ottawa Central Railroad.
Bernie I've had one of those older Atlas - Roco SD35's since they first came out in the early 80's. It always has run well but does have mechanical noise. Nowhere near the noise level of the Athearn BB's though. Good to hear yours only had dirty wheels.
Electricity takes the path of least resistance so when running with an engine with clean wheels the clean wheel job would draw all the current leaving little or none for the problem loco.
Bernie I've had one of those older Atlas - Roco SD35's since they first came out in the early 80's. It always has run well but does have mechanical noise. Nowhere near the noise level of the Athearn BB's though. Good to hear yours only had dirty wheels.
Electricity takes the path of least resistance so when running with an engine with clean wheels the clean wheel job would draw all the current leaving little or none for the problem loco.
Electricity takes the path of least resistance so when running with an engine with clean wheels the clean wheel job would draw all the current leaving little or none for the problem loco.
