# Bachmann Indy DCC Conversion



## Peter Osborne (Jan 5, 2008)

I have my Indy all pulled apart for the conversion. I had expected it to be pretty easy as there are 6 electrical connections between the loco and the tender, eliminating the usual need to add any. I've removed the sound card from the tender and now have the locomotive apart to trace the wiring. This locomotive has a level of electrical complexity above the 10-wheeler, as there's a circuit board in the loco which provides a regulated supply to the smoke unit (didn't work from day one) and it also drops the voltage down for the LED lights, front and rear. What I was surprised was to find was three wires going to the motor. A blue and green wire go to the two tabs on the end, but a white wire also goes to the metal case of the motor?

So, I'm about to rip the circuit board out of the bolier, plus the NRMA switch and just leave the smoke switch to use with a replacement Bachmann smoke unit I've had around for ever. I had planned to place the decoder in the tender, but there is space in the loco with the board removed. However, that space may end up being used to add some more weight to a notoriously light engine, so I'll probably stay with the tender install.

Just wondered if anyone knows the purpose of the white wire?

I'll be experimenting with a new (for me) sound decoder, an MRC 1819 which is very attractively prices at around $70 retail. I'll be posting my observations, and if I remember, photos at this site over the next couple of weeks.

White wire anyone? 
Peter


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## Road Foreman (Jan 2, 2008)

Peter, 

Sounds like the white wire is a ground wire.. This would be used for noise suppression of the motor.. I would save it, but I do not think you will need it with the DCC decoder.. I would also install the decoder in the loco, that way you have 2 wires for the rear lite, 2 wires for the speaker & 2 wires for track power to the loco.. That way you can add cab lites & smoke control with out extra wires between the tender & loco.. 

BulletBob 

PS Looking forward to the pictures of the install..


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## Peter Osborne (Jan 5, 2008)

OK. So I changed plans and decided to replace the Bachmann smoke unit with a 5v LGB unit that I had unused from another project. Fortunately I also had the components to build a simple 5 volt regulator circuit and after checking with George S's (my hero) web site, I had the circuit built, hooked up to the smoke unit and tested. Then I had to drill out the stack to accept the smoke unit. That didn't go as well when the drill heated the stack up and the thin plastic buckled a little. Probably nobody else will notice - but I know. 












So, above is the loco pulled apart and ready for surgery










Above, the gutted tender and the MRC 1819 decoder shown to give an idea of its size. I have the wires marked up ready for reuse. Since this decoder does not have a mechanical chuff capability, I plan on using the two wires that previously triggered the Bachmann board to carry the power back to the motor. One of the other pairs will carry the pickup from the six driven wheels back to the decoder, the other pair will connect to the LED front light.










The regulator circuit has been hot glued into the boiler after testing on the bench.










The LGB smoke unit visible in the stack. It will get some engine black later so it's less visible. If you look carefully, you can see a slight kink n the stack where it got hot when I was boring it out. The air tanks, not visible, have been filled with lead shot and hot glue. Hopefully a little more traction will result from this.

Next, I'll be installing the decoder in the tender.


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## Peter Osborne (Jan 5, 2008)

Tonight I finished the hook up inside the locomotive and closed it back up. Went easier than I expected. Then I connected the wires within the tender and made sure everything still worked on DC. Success, so I connected the 4 wires to the decoder and plugged in the diminutive speaker that comes with the decoder (see picture). Switched the test track to Main, more success, sound, smoke and action were to be had. 









Now you will be wondering about the speaker. Well, MRC advertises this as a O/G scale decoder, so I guess this little guy may make sense for some installs. However. I have a 2.5 inch 4 ohm (yes, the spec states four ohm) speaker due for delivery this week, and that will be used here. The Indy tender is very small for G scale, so I am anticipating some surgery on the tender to liberate some space under the coal pile. Meanwhile here's a close up of the tender with the decoder and temporary speaker in place.










And here's a close up of the top of the tender with some tentative markings where plastic may need to be removed.










As you can imagine, the sound right now is horrible, but I think it will be acceptable once the larger speaker is installed and the tender reassembled to form a basic baffle. I need to fiddle around with the various CV's to get the start voltage, auto chuff etc adjusted and figure out what value of resistor I need to install before I connect the LED head and tail lights. Fingers crossed and hopefully, an update next weekend.


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## Peter Osborne (Jan 5, 2008)

So UPS delivered the new loudspeakers right on schedule and I was pleasantly surprised to find that they fitted the cutout in the tender without any modification. I hooked up a 1K ohm (the instructions suggest a 2k, but that seems wrong) resistor to the blue common wire for the head/tail light hookup and used a couple strips of double sided foam tape to secure the decoder while I put it all back together. 









Not the tidiest install.... but everything works.










Side shot, shows how compact the new 4 ohm speaker is..

I got it here...

http://estore.websitepros.com/1736754/Detail.bok?no=485http://estore.websitepros.com/1736754/Detail.book?no=485

the minimum order is $25 so I have two spares for future installs.










Speaker fits great. No need to remove any of the tender shell to provide clearance.

Sounds good also. Plenty of volume for a small locomotive. I think in a larger locomotive, some people would be looking for more volume. I'm still experimenting with the various whistle and chuff options. I don't have a digital video capability right now, so maybe I'll try to upload a wave file so you can get an idea of the quality.


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## Road Foreman (Jan 2, 2008)

Peter, 

Thanks for the update!! 

BulletBob


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## Peter Osborne (Jan 5, 2008)

I spent some time programming the MRC 1819 decoder with my command station (MRC Prodigy Advance) but that became a frustrating exercise, so I took the ultimate step which was to purchase a SPOG 2 and start using Decoder Pro.

Thats been a fascinating journey in itself and the folks over on the JMRI forum on Yahoo have been outstanding in getting me started and providing assistance. Although large scale experience is pretty thin over there, Decoder Pro and DCC is scale agnostic and once you start leveraging the knowledge of the HO and N scale community, there's a great deal available. 

I couldn't track down anyone who had a configuration file for the MRC 1819, so I started by grabbing a existing MRC brilliance file (for a N scale decoder!) and making one. I had help from people on both coasts who reviewed my changes, found my XML bugs and actually coded some of he more complicated parts. So yesterday, with the new config file, I spen an hour tuning the settings of the decoder, switching back and forth between between program mode and ops mode to test the changes. It was interesting to see that some of the settings I thought I had made were not so when I read back all the CV's at the start of the exercise. 
I'd used the Loksound programmer to tailor the settings in their XL decoder which is an expensive, but favorite solution of mine. But now I will have the same graphic capability and ability to store the settings in a rooster for all my decoder/locomotives combos, which saves me from having to record them elsewhere. So I'll be using Decoder Pro in all my future CV only tuning. For downloading new sound files, you still need the specific version for that brand of decoder


Anyway, I was able to get the chuff very closely sync'd to the wheel revolution, adjust the start voltage, kick start and high voltage until it met my expectations. I adjusted the various sound levels (all separate controls) and in my basement, the mid range overall volume setting (0-3) was plenty load enough. Now all this was on rollers so I need to wait for the full field trial results, but I have to say that I think the MRC 1819 is a great option at the price ($70) and I look forward to using it in several more installs.

In fact today, I start the install on my LGB DRGW Forney, following Bob Grosh's fantastic directions.


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