Kit: MX648; IceCube18X13X07-1W; SACC16 + 3x 470uF Narrow/Tall Tantalums for Stay-Alive; Firebox Glow, Crew
Oxford have had a few attempts at OO locos, all of which have had excellent detail, but not always mechanically consistent.
However, they seem to have hit the nail on the head with this N7, as it not only looks great, but it runs very well and carries
a lot of weight - nice job!
3 screws removed and the body eases off. No room for kit anywhere except the bunker, as there is so much metal to give it its'
good running and traction. Even the bunker is quite limited on space, but it is a good shape and should prove enough for what
we have in mind.
A quick measure-up shows that an IceCube18X13X07-1W will go alongside a cut-down SACC16 PCB and 3x 470uF Tall/Narrow Tantalums
for stay-alive, with enough space below for the decoder and some wiring loom - should be just about spot-on, though it is clear
that we'll have to be neat, and the 8pin DCC socket will have to go, in favour of hard-wiring.
So here is our proposed kit:
We initially remove the model's PCB, but it becomes evident that the sprung-loaded pickup pins need to push onto the bottom of
this board, and it may be awkward to rewire direct from the pickups, so we elect to cut the board instead - retaining enough of
it for the 2 screw positions, but removing the rear section where the 8pin socket is.
Note that the pickup pins touch the underside on the round pads marked TR1 and TR2. We'll need to solder the decoder's pickup
wires somehow, so we use a knife to scrape a patch on each side along those PCB tracks, exposing the copper - you can see this
in the final picture below where the board has been screwed back into the model.
Next we do some rewiring of the decoder, swapping some of the original wires for finer decoder wire, and much longer in some
cases, as we need the motor wires to reach all the way to the motor terminals. Unwanted AUX wires for lighting are removed
(white, yellow and blue). We also add wires for the stay-alive kit, and connect up the SACC16 with 3 Tantalums. We solder on
the motor wires (orange and grey), then the pickup wires (red and black) to the scraped areas on the PCB that we made earlier.
We'll leave the blue and green wires on for now though as it looks feasible to add firebox glow to this model. At this point
we can carefully test that it all works, in the correct direction - swap the orange and grey wires around on the motor
terminals if it runs backwards.
Route the wires and use tiny blobs of Black Tack to secure them in position, or electrical tape to protect them.
Ok, so firebox glow... the cab should slide off vertically - just run your fingernail down each side in turn, along the roof
line, slowly easing it up. Our model already had lump coal glued in the bunker which made this process a bit harder, but
carefully working it eventually came free.
Rather than wire in from behind the firebox door, we come in from underneath instead, drilling out a 1.5mm hole enough to feed
a pair of wires through.
Our orange SMD LED is fed down into the hole and carefeully glued to the firebox door. The detail here appears to be mostly
metal, so avoid any short-circuit risk on the LED, we glue on a patch of black electrical tape, then glue the LED onto that. It
is pretty well hidden once the cab roof goes back on.
Add some weathered crew, and dab a little black paint around the white parts of the LED to disguise.
Underneath the cab, we join the LED's blue positive wire to a resistor, protected with heat shrink, then that joins to the
decoder's blue common posiitve wire. The LED's negative orange wire goes to the decoder's FA1/AUX3 output (the green wire).
The final job is to neatly fit everything into the bunker space. We use double-sided tape initially, as this takes virtually no
space. Speaker, SACC16 and Tantalums first, a little Black Tack to secure, then the decoder is seated below them, with the
LED's resistor and any excess wire looped in.
That should almost do it - a last piece of tape to hold down the wires and encourage them towards the bunker space, put it
together and test.
All-in-all, very impressed with this model, and the combination of kit we've got in works very well - plenty of noise from the
speaker, enough back-up from the stay-alive for reliable running, and a great firebox glow effect bouncing around in that