I replaced the two motor blocks,and one is not working. I checked all of the wires and they are all good. clean all the contacts and they are good. what could be my problem?
The weakest link in the chain is the contact plate between the truck and the chassis. I think Bachmann just uses plungers for contacts on this loco. Many folks who take things apart to that level end up hard-wiring the connections. That'd be the first place I'd look.
If it's just one motor block not running, then the trouble has to lie in the connection from the on-board electronics PC board (which feeds the two motor blocks) and the motor itself. If you can, drop the motor block to make sure the motor is getting power from the connecting pad on the top of the block. Then trace backwards to the PC board. It could be a broken wire or something like that.
Hope that gives you some idea of where to start looking. It's hard to diagnose with any specificity over the internet.
Later,
K
Kevin is correct about the plungers on the 45 tonner. They are the most likely cause. The springs in the plunger often fail after being overheated or when the loco derails and a short occurs which cooks the spring. When disassembled it is also possible to lose a spring without noticing.
There are four plungers in each truck, two bring the power from the track to the PC boards and the other two bring the power from the PC board to the motor in the truck. With the power on the track lift the good truck of the rails. if the wheels are still turning the plungers from the track to the PC board on the problem truck are OK do the same with the problem truck and if the wheels still turn on the good truck the pickups are good on both trucks
Next remove the problem truck and using bare leads from your power pack test the truck to see if the motor turns. This test eliminates the motor as the problem.
Next use two wires with bare leads, apply power to the locomotive and run the bare leads from the contacts in the chassis to the contacts on the truck. If the truck now runs you will know for sure the problem is with the plungers.
If the problem is the plungers, you can try replacing the springs which are usually the culprit, or better yet bypass the plungers and hardwire the trucks.
I always recommend hardwiring, because I had plunger problems on both my 45 tonners. On one I had just replaced on bad spring when the unit derailed causing a short which fried the springs again.
That was it for me and I hardwired both units and have never had a problem since.
Hope this helps.
thanks for troubleshooting.I'll try your advice.I may ask for more help later