soundtraxx 750 decoder in 2-6-0 loco

[dwbum]

I installed a Soundtraxx 750 decoder in my Bachmann 1363 2-6-0 loco.
At first power on, there was a short circuit; by process of elimination (removing wires) id discovered that the blue, common, wire caused the short. I disconnected the blue wire and the loco runs. However, the loco sputters (don't know how else to describe it). Almost as if a capaciter is discharging.
Any ideas as to the problem and a solution?
By the way, the loco ran bafore with digitrax decoder and alo with a MRC sound decoder.
Don

[dwbum]

Gentlemen,
I removed the connector I attached to the Soundtrax 750 decoder and attached another connector plus the capaciter that came with the decoder; also, cleaned loco (tender) pichups and the problem went away.
I appoligise for causing any confustion.
BTW the soundtrax TSU 750 is a good match for the alco 2-6-0 loco.
I think I will get another TSU 750 and put it in the 0-6-0 switcher what I have made several modifications to.
Don