Zimo MX648 and SugarCube install in a Dapol Class 56 N Gauge diesel... one of the easiest diesel locomotive DCC sound installs to
do in N Gauge, without any modification to chassis!
Disassembly requires removing the frame, clips, bogies, circuit board, and all wiring. We don't need to disassemble the chassis itself as
it doesn't need to me modified in this installation.
Remove the 2 small metal blocks in the fuel tank, as we need all this space for the speaker and associated wiring. Drill and file a neat
rectangular aperture in the bottom of the fuel tank - it will be bigger than the SugarCube speaker, but that's fine.
File the screw threads off the top of the plastic body retaining clip where the circuit board was mounted - we don't need these any more
as we won't be using that circuit board. This frees enough space for the Zimo MX648 to sit neatly. Note the 2nd picture below has the motor
wires soldered directly to the motor terminals (orange and grey wires from decoder), and the purple speaker wires are also threaded down
and through to the fuel tank. Pickup wires (red and black) are also soldered to each end of the chassis.
The enclosure to the SugarCube speaker has been reduced to just a few mm, tested fitted to ensure it is not proud underneath,
then purple wires trimmed with a little lea-way remaining. A blob of super-glue goes onto the bottom of the motor and when we are
happy with the fit, the speaker is attached on the glue blob, ensuring it is neat, square, and flush with the metal side of the speaker
facing downward, away from the motor, and toward the track. Cover the metal of the speaker with electrical tape - no, it does not affect
the sound at all!
Re-fit the bogies and give it a test run - motor and sound should now work!
Now to rewire the factory lights... make re-use of the 4 SMD resistors on the factory circuit board by carefully cutting out that portion
of the board. You may be able to visually see which is the common side from the circuit's track, but once identified, wiring is fairly simple...
The common side may need joining right across if you cut very close to the resistors, but then you can simply connect the decoder's blue wire
to it. The other side of the resistors will go off to the individual lighting features: one for front lights, one for rear lights, and then we'll use
the other 2 to add independent cab lights!
Our cab lights are SMD white LEDs, shown here glued into the cab backplates and also with driver figures added. These are actually rather large LEDs
so you could consider a micro or nano LED instead, which will be just as effective.
Chop the plugs from the factory lighting boards and connect their wires appropriately to the resistors (+ve) and decoder white/yellow function output
wires for the directional lighting. Test the boards to work out which wire is which (one will be +ve), but remember to test with a resistor
in the circuit, or you'll blow the LEDs!
Finally, tidy the wiring, test, and reassemble!