Dual decoders, even when from the same manufacturer, can be a real pain. Since there's not enough room in the boiler shell for a sound decoder, I'd consider removing the 8 pin socket and using some micro connectors to run the wiring back to the tender and put a sound + motor decoder in the tender. It really enhances a steam loco if you cna put a small speaker in the smokebox area or at least somewhere in the boiler in addition to larger speaker or speakers int eh tender - that way at least some of the sound will come from the loco which is where it's supposed to come from. Not a simple plug and play job but it should be possible to get the wires routed and then you have all the space in the tender to work with.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I did that some years ago with Digitrax DZ125 in the loco and a Tsunami 750 in the tender. Worked ok. Had to put a 100 ohm, ½ watt resistor on the 750 motor leads for acknowledgment by my NCE Power Cab.
Had to fine tune to keep from overheating the resistor. Look at the link. Scroll down a ways.
Sound usually needs feedback from the motor but you don't get that with this method.
http://mrdccu.com/curriculum/soundtraxx/tsunami.html
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
I have a Rivarossi "Red Box" DCC-Ready FEF-3 that has an NMRA 8-pin socket in the locomotive under the removable sand dome. The space for the decoder is not very big (15x30mm) so I probably need a "micro" size decoder. The problem is how to add sound. I took off the boiler (a task in itself) and looked closer at the space available inside but everything is so tightly fitted that it would be almost impossible to even get WIRES out of that area. So I was thinking that one way to do it would be to put a non-sound decoder in the space provided in the locomotive and then add a sound-only decoder in the tender.
How well does the dual decoder thing work? Anything I need to know or watch out for? Any suggestions would be helpful for a combination of decoders that will "play well together" (i.e., compatible CVs & functions). Or does anyone have any ideas on how to get a couple of speaker wires out of the DCC-plug area of this locomotive?
One combination I'm looking at is a LokPilot decoder for the locomotive and a LokSound decoder for the tender. Since they are from the same company, I would assume the default function assignments and CVs are compatible. As far as I know though, LokSound doesn't make a sound-only decoder so this would be a more expensive way to go. I'm still looking at what is available from Soundtraxx, Digitrax, QSI, Zimo and TCS. I assume mixing products from different companies makes things more complicated.
To program both decoders I heard about a trick of assigning different short addresses (1 and 2 for example) but the same long address. That way both can be set up separately then CV29 set to change to long addresses for operation so both respond at the same time. Anyone have any experience doing this?