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Graham Farish N gauge Blue Pullman DCC Sound

The Graham Farish Blue Pullman set is the pinnacle of N gauge DMUs. One of the most popular of all recent releases, adorned in sumptuous detail, and a fantastic runner with motors at each end.

However, it 'needs' sound, which as it turns out is not too hard to achieve. 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 either a CT SL76 or Zimo MX648 decoder, with sugar-cube speaker can be installed with minimum fuss. We'll also fit a standard CT DCX76 single-sided decoder to the rear motor car, as we are only putting sound in one end.

First let's look at the 6pin direct plugin CT SL76 sound decoder...

The 2 motor units, with the SL76, speaker and a capacitor at the top of the shot, and the DCX76 at the bottom. The capacitor used here (16V 100uF) acts like a stay-alive, but in reality it justs gives increased reliability to the sound, removing potential crackles from the amplifier. If doing this yourself, ensure that the voltage rating of the capacitor is equal of slightly higher than the DCC voltage that you run your track at. The decoder can manage up to 35V capacitors, and a 35V/100uF will fit in using exactly the same procedure (picture below is the 35V version):

Pop out the chassis from the body starting at the rear, then carefully use a fine flat-head screwdriver to open the front away from the chassis and it should just pop off - a bit of a tight fit, but it will come:

This one is unit 'F', which is the rear motor unit. We will simply take out the DCC blanking plate and insert the CT DCX76 decoder, component side up. After doing this, you can pop the body shell back on and test that this motor unit functions correctly:

The fun starts here... the CT SL76 in its 6pin direct plug-in form, alongside the amazing CT sugar-cube speaker (unmodified) and the little capacitor (photo here shows the tiny 16V version):

You need to unscrew the circuit board and pop it off (no need to remove any wiring):

The sugar-cube speaker will sit under the circuit board in the area between the motor housing and the seating, but we need to remove a small dividing wall from the grey plastic. Don't worry though - it is a part that is not visible when the body shell is put back on:

It is possible to cut the required plastic out with the seating still attached to the chassis, but you may find it more comfortable to remove the seating unit. This will also be cleaner, and you'll be able to get the angles you need for the cut more easily:

Work your cut as squarely as you can to keep it neat:

When the cut is done, it should look something like this. File any burr away to make it smooth:

Refit the seating to the chassis:

Test-fit the speaker now, electrical connections upward. It will sit snuggly in the enlarged gap, slightly depressing the electrical pickup contacts below, but this is no problem - it won't affect pickup or motion. When you are happy with the location of the speaker, use some thin double-sided tape across the whole area and stick the speaker into it's new home:

Place some electrical tape around the underside of the circuit board above where the speaker is located to avoid short-circuit with the speaker. Refit the circuit board, making sure to keep the motor connections on the outside on both sides, and screw the board back into place:

You may find that the circuit board bows just very slightly upward over the speaker - don't worry though as there is plenty of room for this to fit ok:

Plug in the SL76, ensuring that the round component in the centre of the decoder is face-up. If you get it the wrong way around it won't cause any harm, but the lights will be permanently on and the motor won't respond!

Trim the brown speaker wires to a comfortable length and solder them to the speaker contacts, which should be accessible still:

If you want to use a capacitor (recommended, but not essential), then connect this between the blue wire of the decoder (common +ve) and the decoder's GND solder pad (ask YouChoos to pre-solder wires on for you if you purchase the decoder from us). The +ve side of the capacitor is the one where the black plastic shoe has angled corners. The -ve is the straight-sided one, but can also be identified by the black printed block on the top-side of the capacitor (useful if you decide to remove the plastic shoe!). Note that wire colours may vary for the -ve capacitor wire:

Thread the capacitor through the plastic O ring on the rear of the chassis and secure with some chunky double-side tape, or something similar.

Train the wires high up so they won't be too visible through windows when you put the body shell back on:

It is worth gently bending the lighting contacts down in the nose of the shell, to ensure they get good connection when you put the shell back on:

Finally, pop the shell on and test that everything works ok:

In particular, 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). The motors are engineered very well, and will probably match very closely in characteristics:

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

Alternative to using the CT SL76, below we see a Zimo MX648 decoder with a 6pin plug on a short wired-harness instead. This actually produces better results than the CT, with more reliable running too. With an MX648 at each end, drivers and cab lights too, this gives a very pleasing result..


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!