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Bachmann OO Class 08 Diesel CT DCC Sound

Installing DCC sound in a Bachmann OO Class 08 diesel using a tiny CT SL76 decoder...

Remove couplings. Unscrew coupling mount at front (single screw), and remove mount. Unscrew 2 retaining screws at rear, either side of coupling. Undo the tiny screw which was under the rear coupling and use a flat-head screwdriver to gently bend back tab in the little recess and ease the body off the chassis:

Study the chassis, motor and wiring. Unscrew and remove the 8-pin DCC socket. Unsolder wires from motor terminals and from pickup strips:

Remove the motor capacitors as they have no value after DCC is installed:

We will not be adding any lighting to this example, so we'll remove the white, yellow, green and purple function wires from the SL76 decoder which will keep it tidy, with less to get in the way. Keep the blue common positive wire, as this will be used for the +ve side of a stay-alive capacitor. We reuse the purple wire and solder it to the spare pad next to the blue wire's pad, which is the -ve connector for the stay-alive:

Use high-tack double-sided tape, or similar to mount the sugar-cube speaker to the front of the chassis where the DCC socket was... just to the side of the socket screw points. The CT sugar-cube does not need any modification in the Class 08. Best to point the speaker terminals outwards a little and at the top as it will make soldering easier later:

The SL76 is thin enough to be mounted on the side of the motor, but may be easiest to use thinner double-sided tape, perhaps with a thin electric tape directly on the motor itself:

The original top screw hole where the DCC socket was mounted provides a very convenient place to thread the speaker wires, which will keep them away fropm the spinning counter-weight of the motor. Thread both brown speaker wires through, cut to a comfortable length and solder them to the speaker terminals:

Route the red and black pickup wires down through the provided channels and neatly solder them to the same location as the original pickup wires:

Solder the orange and grey wires to the motor terminals and test that the direction is correct. Do NOT trim these wires until you have tested direction, as you may need to swap them around to get it right. Once your are happy with direction, trim the orange and grey wires and solder again to make it permanent:

We will now install a very large stay-alive capacitor inside the cab. You don't need one this big, and will need to use a smaller one if you plan to add crew or cab lighting, but in general, bigger is better with capacitors! The blue and purple wires need to be fed through the cab floor. Drill a small hole large enough for the 2 wires, and optionally create a shallow channel to give the wires somewhere to sit along the plastic body edge on their route from the decoder to the hole:

Test everything again before re-fitting the body, and before connecting the capacitor. Add a little electric tape against the body side, inside, adjacent to where the decoder will be, to protect the plastic from the heat of the decoder (shouldn't be a problem, but these decoders can get quite hot!). When you are happy with the fit, put the body shell back on (not the cab though), ensuring that the wiring is neat as you go:

Trim the blue and purple wires, and connect up the capacitor (take care of the polarity, as it will blow something up if you get it wrong!). Use some high-tack double-sided tape to stick the capacitor into place, ensuring that it has enough clearance either side, and at the back for the cab to be able to slide back on (in a moment). Test again:

Finally slide the cab back on, which should click back into place with its tab at the back.:

All done!

Disclaimer

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.