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Athearn SD 40-2 problems Locos and rolling stock
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Active Member 51 posts snotoy2 Active Member 51 posts
snotoy2

I have a Athearn SD 40-2 that has a serous electrical problem. When I remove the shell the chassis runs great but as soon as I put the shell on my power supply reads a short. I do not have any metal inside the shell and I have removed the power strip and have soldered jumper wires to the trucks. Can anyone please tell me what to check next?  

T.J.
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Alco_nut Regular poster 401 posts
Alco_nut

try this

With the shell off connect an ohm meter across a wheel set. Slowly put the shell on,watch the meter to see if you can tell when the short occurs as you put the shell on. It must be pinching something. Check all wires for any nicks in the insulation.

Bob

Jersey Northern RR

http://jerseynorthern.webs.com

https://youtube.com/channel/UCyAziSSu5A6d8ojWBiG1xGQ
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Larry of Z'ville Frequent poster 984 posts
Larry of Z'ville

A common problem with BB locos

The light assembly is high and when the shell is installed fully it touched the tower clip.  Usually if you just set the shell on the chassis and do not push it down fully it will run fine.  The assembly is holding it up, but the contact has not been made.

The solution is to make sure it is installed in its lowest position.  Another thing that can cause it is if the cab window rectangle is backwards.    The center clearance heights are different.  The shorter one should be forward to minimize this interference.  

Sometimes it is difficult to fix the actual issue, but if you have five wired this unit, you can cut the tower clip and that will eliminate the interference that causes the short.  

Good luck

So many trains, so little time,

Larry

check out my MRH blog: https://model-railroad-hobbyist.com/node/42408

 or my web site at http://www.llxlocomotives.com
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