Troubleshooting a GP40

[rainynight65]

Hi all,

I recently bought a Bachmann GP40 (model 63518) from a local shop. It's the DCC-ready model with an 8-pin plug. The intent for me was to fit it with a DCC decoder, however I haven't had much luck with it. The loco ran for a bit, but it seems there's a problem somewhere in the motor or the drives. I don't have a DC controller myself, but I took it to someone with a DC test track. They popped it on, and it would barely run forward at all - a few jerks when nudged. It ran backwards for a bit, but then stopped doing that as well. The lights are working at all times when there's power on the track.

It is well possible that the loco has sat on the shop shelf for a few years, I got it fairly cheap, but the pack was unopened. I'm a bit of a newbie, especially when it comes to loco maintenance. I haven't had a loco long enough for it needing maintenance. Without spending too much money, what can I do to try and salvage this one? I read something somewhere about hardened grease, could that be a problem? Any other hints or advice?

Thank you in advance.

[rich1998]

We arre assuming, no decoder yet.
If there is hardened grease, it would have to be sitting for quite a while but possible.
You are going to have to take the shell off anyway to check it out.
I would doubt a drive shaft fell out since it appears it has not been run. New out of the pkg.

When you get it running well, get a Digitrax DZ126PS decoder. A quality decoder. One amp decoder.
I have used the older DZ125's in a couple Bachmann locos and they were really good.

Also, any caps on the PC board, cut them. They usually affect slow speed with quality decoders on Bachmann locos. They might be yellow blobs and marked with a C. The two items with a L are chokes. Ignore them. They might be wire coils or look like green resistors. They have zero resistance.
They do on my Bachmann locos.
There is a decoder company that makes a complete quality decoder to replace the complte PC board and it comes with LED's but I will not go down that path now. Maybe a PM if you ever get interested. About the same prices as a DZ126PS.

Rich

[rich1998]

I recall a thread a few years ago on removing the shell. I think it was, pry the full tank off and there are four screws under to remove. Pull the shell up. Not sure about the couplers. There are some here who know for sure.

Rich