A couple of you wanted to know the details on how I added sound to my N scale Hornby U25C. I apologize for doing this without photos, but I didn't take any when I did the work, and since its a PITA to open it up (need to remove the couplers), I won't do that until there's another good reason.
When I first got the shell off (and the stock couplers fell apart), the differences between this and the usual Atlas/Kato units was daunting. But after I studied the layout a bit I realized this might be one of the easier conversions I have done. I had a LokSound Micro decoder on the way, and a Soberton speaker (with Keystone Customs Enclousure).
It appeared that if I cut the middle section out of the standard circuit board, and mounted the decoder on top of the frame, that there would be enough clearance. Well, there wasn't, I needed about 1/32" more room. Since we've heard that there might a new decoder available from ESU based on the OEM decoder in the Intermountain SD40-2, I called in a favor at IMR and asked them to tell me how thin their decoder was. "Real Thin" was their response, but further probing suggested it was on the order of 1/10"! If that decoder was available, that would solve the issue. But nobody knows when it might be, so I decided to continue with the Micro. I realized that the part of the frame on top of the motor is removable and would be easy to mill down. I then found out that the motor is mounted with the screws through the fuel tank so I could basically remove that piece on top' The motor would still be firmly mounted, and there would be plenty of clearance. It wouldn't cost me very much weight either. The plastic body shell is just a little too narrow for the decoder, but with my special grinding tool, made from an electric toothbrush, was able to remove the material needed.
For the speaker, I realized there was enough room under the circuit board on the rear end for the speaker and enclosure. I just needed to cut about 1/4" of the top of the frame there. Very little weight lost again. Glued the enclosure to the bottom of the circuit board with the speaker diaphram pointing inward. The speaker wires were easily exposed and could be routed under the circuit board back to the decoder.
At that point I was very happy with my work, but then the frustration began. During my work the handrails continually would fall off. I tried to keep them on as much as possible. I think I need to use some super-thin CA glue. I had also bent the pickups on the circuit board that contact the truck contacts and they weren't consistently making good contact, so I decided to solder wires between them (like the Athearn Blue Box diesel fix). That solved any contact problems.
As for the couplers, I decided I would use a set of MicroTrains 1015's. I needed to grind the ridges off the frame mounting point and enlarge the openings on the pilots. It's still a tight fit and hopefully the shell doesn't need to come off very often.
Since the light circuit board was cut in thirds, the two end parts with the LED headlights and number board lights might be usable. I haven't figured out the traces, and I usually only worry about headlights after I am satisfied with how it runs. I might wait until I put a decoder in the second unit. I can't afford sound in everything, but I will probably want a LokPilot in it so that I can have Full Throttle (when the LokPilot support it).
Oh yeah, I also had to adjust the wheel gauge, all axles were too narrow.
I am happy with the result, but the entire conversion was a bit more frustrating than I had hoped for.
I expect some modelers with be frustrated with these, the handrails, the electrical contacts, and the wheel gauge, so I wouldn't be surprised to see them on Ebay as "Projects" with no handrails.
Bill Kepner
