Kit: Zimo MX648 with Minnow6
So apparently (I'm told), the Hattons Andrew Barclays will be "nigh-on-impossible" to fit DCC sound into... well, there's a challenge if I
ever heard one! Well "Katie" turned up in the post, looking smart, well weighted, well detailed, and runs reasonably well on analog - a bit
stuttery, but then this is one very small engine.
Remove the 2 retaining screws underneath, and unpin a couple of the detailing bits, and the chassis comes out - quite a tight fit, but
gradual movement at each end, and it eventually comes clear. Little motor and 6pin DCC socket revealed.
Simple DCC fitting would be easy enough, using a Zimo MX616N - just play-and-play. However, for DCC sound, a careful bit of measuring
suggests that a smallish speaker will slot up into the nose - perhaps a Minnow of some sort (there's a nice recess there, although not especially deep), and just maybe
an MX648 sound decoder will go sideways if the DCC socket is removed. It'll be tight though...
So, motor out, DCC socket out, leaving the existing pickup wires available to connect our decoder onto.
So, that's the aim - MX648 with Minnow6...
The MX648 is definitely too wide with the heat shrink on, and the wires need to be switched around so they don't poke off the end,
making the decoder even longer. So, remove the heat shrink, and reverse the direction of the wires on the end row, also removing any
unwanted wires, such as those for lighting.
Protect with Kapton tape, with a little opening on the pad side so the wires have somewhere to go - this will be upwards and away from
anything conductive in the model, so will be safe leaving that little part exposed.
Test fit - slots in reasonably comfortably, albeit at a very slight angle.
Chop off the PCB holder nugget from the model to make the platform flat.
Solder up the motor, pickups and speaker. Note how we left a short length of BLUE wire on the decoder, as well as a short extra grey wire
on the GND pad - just in case we decided to try to add a stay-alive kit later.
Drill a small hole down through the chimney to give the sound somewhere to escape. Not sure if this made any genuine difference but
seemed like a good idea at the time!
Fix the Minnow6 speaker into the nose with Black Tack, and the MX648 at a slope in front of it.
Test for direction (reverse motor wires if operates the wrong way around), and slide the body back on ensuring not to pinch any wires
on the way through. The chassis is VERY tight in the body, so be patient and gradual.
Back on track and working pretty well. Perhaps could benefit from stay-alive, but good considering the size. With a bit more squeezing, it
may be possible to use a cut-down SACC16 stay-alive connection board, with 1 or 2 Tantalums, but I'm not trying that today!
...Ok, so it's now another day! Time to add stay-alive and reload with YouChoos' new Andrew Barclay sounds...
We cut down the SACC16 board and add just a single 330uF Tantalum (flat variety), attaching it to the same side as the kit's surface mount components in order
to keep it as low-profile as possible. Cover in Kapton tape and connect up to the decoder's common positive and ground pads. Mount the kit on top of the decoder
using some thin double-sided tape, and put it all back together. Of course, a bunch of detail parts come off in the process, but are not too hard to put back! Then
we have the final article - "Katie" with sound and stay-alive - marvellous!