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Bachmann OO Blue Pullman DCC Sound

The Bachmann OO Blue Pullman show-cases modern manufacturing techniques to the full. It is a stunning model, covered in detail, powered at both ends and filled with excellent lighting straight from the factory.

It has even been designed with DCC Sound in mind, with reasonably comfortable space for both decoder and speaker. Choose between sound at one end, or both, as long as the decoders match their speed closely with similar acceleration/deceleration and top speed characteristics. If you decide to go with a dual-sound configuration, YouChoos will normally supply 2 different sound projects which have slightly different startup/shutdown sequences as well as restricting the callable sounds to one end or the other (e.g. F4 operates horn at front, F5 operates different horn at rear, and so on) - just ask when ordering if you are not sure!

In this guide we'll demonstrate how the CT SL51-4 21-pin MTC decoder, with 20x40x10mm bass reflex speaker can be installed with minimum fuss.

NB Suggest using Zimo MX644D decoders instead, with IceCube25X18X08-1W speakers.

To remove the body shell from the chassis you need to take out 4 screws in total (2 at each end of the unit, diagonally opposite each corner of the bogies:

With the shell off, it reveals a large space where the factory-fit decoder is located:

Carefully remove the existing 21pin decoder, which you can reuse in another model, or just store away:

The next step is to fit the speaker. The loco's circuit board provides 2 solder pads for it, so simply solder your speaker into place. You may need to extend the speaker's wires a little as shown:

If your speaker is supplied with plastic screw lugs, cut the lugs off and file them down flat, otherwise it will be too long to fit in the space. Even so, the wires cause it to be too long, so you'll need to cut a slot in the grey plastic wall in front of the decoder/speaker area for those wires to feed through and back - don't worry though, as it isn't major surgeory:

You should also fit the CT SL51-4 MTC decoder now, before putting the speaker in place:

You can secure the speaker in place with a piece of electrical tape, although it isn't going anywhere(!):

That's it! Put the body back on, screw together and test it all out:

Once you have done both ends of the Blue Pullman, test the front and rear motor units closely on the track (but not coupled). Run them back and forth, altering acceleration (CV3), deceleration (CV4), top speed (CV5) and backEMF (CV50) to match as closely as you can. If you use CT decoders in both ends then this shouldn't be too hard - just give both decoders the same values e.g. CV3=20, CV4=15, CV5=0 (no top speed limit) and CV50=255 (max). Check your decoder manual to see if the CVs have different meanings (the Bachmann decoder may not use CV50 to control BackEMF for example!). The motors are engineered very well, and will probably match very closely in characteristics:

Here's a short video demonstrating a good-matching performance at both ends...

If the volume is too loud, simply turn it down using CV121 (range 0-63), and enjoy!

NOTE: references to CVs here relate to CT decoders only, and may not be correct for Zimo or other types!


Please note that these guides are provided as useful resources for you, as-is. YouChoos cannot be held responsible for errors in the information, or for any damage caused to your models or equipment if you choose to follow any of the steps detailed here.

A bit of YouChoos poster art for your enjoyment!