I spend all day yesterday converting a Bachmann Spectrum 4-6-0 into Bullfrog Goldfield #12. A major portion of the project is connecting their 4-6-0 to the Bachmann Vanderbilt tender. The tender has an oil bunker and is designed for their 2-8-0 and doesn't work at all with the 4-6-0. The space inside the tender is small and singularly designed to defeat all attempts in putting a sound decoder and speaker inside and actually getting it re-assembled.
Despite multiple missteps I finally got the whole thing to run with the sound and the headlights working correctly! Looks great. The only problem now is that every once is a while it suddenly reverses. It stops and goes backward without me doing anything. Blowing the whistle seems to trigger is occasionally. A derailment or short will trigger the sudden reversal. The decoder is a Digitrax. Could I have I have done anything wrong with the installation that could cause this? Should I just replace the decoder? Sigh!
I know you said decoder, but just to confirm, are you operating on DC or DCC?
Whatever is the case, I suggest resetting the decoder to the default values and reprogramming it again. It sounds like you may have accidentally done something to automatically link the reverse to other decoder actions, which is possible with some decoders.
Mike Lehman
Urbana, IL
mlehman I know you said decoder, but just to confirm, are you operating on DC or DCC? Whatever is the case, I suggest resetting the decoder to the default values and reprogramming it again. It sounds like you may have accidentally done something to automatically link the reverse to other decoder actions, which is possible with some decoders.
After you reset the decoder to factory default values and get your address reset to what you want, reset CV29 to a value of 34. This tells the decoder to operate on DCC power only, and can eliminate a lot of weird happenings with dirty wheels, dirty track, and poor electrical pickup.
Is the Spectrum light board still in the loco? Is there any capacitors across the motor leads? Spectrum locos need to have the caps removed for running a decoder.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
Are you sure this is a problem with the loco and not something else?
If you run a second loco on the same section of track a foot or so behind the Spectrum, do both locos reverse together?
I took the sound decoder out and replaced it with a TCS decoder. It appears to be working fine. I'll put in a deferent sound decoder and we'll see if it misbehaves again. Very weird.
There is still the problem of the front of the tender wanting to derail at the slightest opportunity. They are pretty light and all the wires interfere with the tender. More weight in the front should help as that is what I had to do with the Vanderbilts when putting them behind the Spectrum 2-8-0. Thanks for all of the suggestions they were helpful with troubleshooting this. - Nevin
Many Spectrum engines have an "apron" like real engines, that folds down to connect the cab to the front deck of the tender. When putting the engine on the track, I usually fold the apron all the way up, put the engine and tender on the track, and reach in with a pencil or screwdriver and gently lower the apron to the tender deck. If you don't do that, it's very easy to get the apron stuck under the "lip" at the front of the tender deck, which lifts the front of the tender up and makes the front truck not touch the rails properly. I suspect that may have been the problem when you had the sound decoder in place, but that when you changed decoders, you put the engine back on the track in such a way that the apron wasn't interfering with the tender anymore.
Note that in many Spectrum coal tenders, the coal pile in the tender is a separate casting that you can remove. There's often enough space in there for a speaker. I have a Spectrum 2-6-6-2 with a 1" speaker under the coal pile. I just drilled a small hole to run the speaker wires to the decoder in the main body of the tender.
One problem I have with a Bachmann Spectrum 2-8-0 is with the drawbar. The hole was too small and the pin on the tender kept binding in the hole raising the front wheels of the tender off the rails and also the wires between the loco and tender interfering with the drawbar. I reamed out the hole a little and solved that problem but the wires still occasionally derail it.