Hi, I am experiencing yet another ho scale brass locomotive motor electrical problem. On locomotive #1-I recently rebuilt a brass locomotive all the wires are hooked up red wire to positive and the other end of the red wire to the frame and of course the black wire to the negative and the other end to the draw bar screw. When I put the locomotive on the track, the green indicator light on my power pack does not light up which indicates of course I have a short. I am not certain but I believe that the flywheel is hitting the frame or the trailing truck was not installed properly and shorting against the frame or both. How do I narrow down what the cause is? On locomotive #2 all the wires are hooked up red wire to positive and the other end of the red wire to the frame and of course the black wire to the negative and the other end to the draw bar screw. the indicator light on my power pack does light up green but the locomotive does not run. I have taken the locomotive apart and when I test it without the boiler on the locomotive, the locomotive runs when I disconnect the black wire from the draw bar screw and touch it to the side of the left rail or the left side of the tender wheels. What would be causing this problem? Thanks.
Check the tender wheels to see if any are on backwards.
Hi again Jim, yea that was the first thing I checked they are on correctly. I even checked to see if the tender trucks had screws on them too. Ive had that happen before as well. I think the problem on the locomotive #2 may be a draw bar problem, because I do not think I put it back together correctly when I took it apart. I think I am going to check that. I just read some where else that the draw bar assembly needs to be insulated with 2 washers and a insulating sleeve.
I have had similar problems with my brass. You can use an ohm meter, but I prefer a continuity tester with bulb and alligator clip. This way you can check for continuity(a short) in areas where there shouldn’t be any. For example between trailing truck and frame and move the truck around. You may have to fashion/use insulating washers/sleeves.
Richard
if the tender wheels were on backwards, on the same side as the engine, there wouldn’t be an electrical connection to the same rail. how could there be a short?
i’d try to isolate the problem by using an ohm-meter to check continuity between the tender frame and both rails, with the tender separate from the engine, and the engine and both rails, again separate from the tender.
Is the motor free to turn? You said you just rebuilt it and that the flywheel may be hitting the frame. If the motor can’t turn, it’s essentially a short. Is there still a short without the locomotive body without the flywheel hitting the body?
with the wires disconnected from the motor, you can check for continuity between each wire (red and black) and both rails.
hopefully by doing these tests, you can isolate the problem to the tender or loco, the motor, the red or black path, and find and fix the problem
good luck
Pretty simple really. A dead short would occur if some were on correctly and one or more were not.
Check the loco wheels also. The insulated wheels should all be on one side of the loco and insulated wheels on other side of the tender. An ohm meter or other continuity testing device is a must have. What type of motor is in these locos. If they still have the open frame make sure the brush holders are insulated from the motor case before soldering wires to them.
I messed up one time and put the trailing truck wheel set in backwards. I didn’t realize it until I lost a little more hair. When I assembled the truck it was upside down. Egg on my face situation for sure.
Pete
Ok. The flywheel touching the boiler or frame would not cause a short, unless the flywheel is somehow connected to the “negative” side of the circuit. If the loco runs without the boiler and with the tender, I would suspect that the drawbar is touching the backplate of the cab. This, of course, assumes that the wheels in the trailing truck and pilot truck are correctly oriented. If they are not, you’ve solved the problem.
This one seems to indicate a problem with the drawbar or tender. No current is getting to the motor through the tender. Reconnect the wire to the drawbar, then test by holding a jumper wire from the drawbar itself to the left-hand rail. If it doesn’t go, you’ve found th