Classic UK Minitrix Models  -  DCC Conversion 2
Above the Worm Gear

Much of the logic behind the DCC conversion is covered in the boiler conversion, so I am just going to write a summary here, with an explanation of the photos that I have taken.

The tender provides a +ve pickup via the black lead from the front and rear right hand side wheels.  There is also a -ve connection through the draw bar.  I have never found this to be particularly reliable and with DCC I prefer to provide an extra lead for the -ve pickups from the tender to the loco.  With the boiler weight removed, the tab which presses against the underside of the weight, provides an ideal solder point.

Remove the circuit board - de-solder the wires which connect to it and the ends of the two long arms which rise vertically from the pickup tracks.  Unscrew the board.

The motor needs to be isolated from the chassis.  The lower bush cap has a tag on it to connect with the chassis.  Switch the two caps over so that the tab is on the top of the motor - but not until you have made the necessary soldered joints - later.

There are two tabs on the pickup tracks slightly behind the middle axle.  These can be used to solder a black (left) and a red (right) lead to turn to the tender in place of the existing black lead.  There are two holes at the rear of the cab which will easily accommodate the wire on each side.  Put a small blob of solder on the tab first.  Keep contact with the soldering iron to a minimum - a second should be ample - you don't want to melt the plastic base of the pickup strip.

Use adhesive pads, or double sided stick tape to fit the chip.  Check the body fits on top before doing anything else.  Tuck the ends of the legs under the pad. 

Tin the vertical connectors from the pickup tracks - about midway up their length.  Plan the wiring.  Solder the black and red cip leads to the vertical strip from the pickup track.  Solder the orange and grey leads to the motor bush caps - when they are off the motor.

The white lead for the forward light can be left long for now.

Fashion a shelf - exactly the same size of the removed circuit board - with a hole drilled in the same position.  I used 3 layers of plasticard 0.6mm thick, superglued together.  The bottom layer had a recess cut out to fit around the support into which the securing screw will fit.  At the end, I trimmed 0.5mm from both sides to leave a stub to keep the two arms from the pickup separated.

The shelf secured to the post designed for the circuit board.  The uprights from the pickup conductors need to be tucked in between the shelf and the adhesive pad.  I iended up applying a little superglue to help keep them in place.

The shelf will require a shorter screw to secure it - the existing has a head which is too large and the thread will foul the worm gear.  If one cannot be found, epoxy may do the trick.  I wanted to keep things easy to return the model to DC should I wish to at a later date.

The shelf from above, with the red and black tender leads soldered in place.  Note the small head screw.

Use adhesive pads, or double sided stick tape to fit the chip.  Check the body fits on top before doing anything else.  Tuck the ends of the legs under the pad. 

Cut the leads for the tender to length, leaving a small loop between loco body and tender.  Reassemble the tender.

 

Side view showing the positive pickup lead from the tender soldered to the tag at the bottom of the vertical copper strips.  The red lead is painted black here as it will be visible when the body is put on.  The 3 layers of plastic card and the adhesive pad can be seen clearly in this shot.  It looks like I used N Gauge brick wall for this job !

The fitted DCC chip.  A nice, neat solution.  The yellow wire for the rear light has been cut.  I don't use it.  The white one for the front is a tad short and takes a diagonal path up the right hand side of the boiler weight.  Care has to be taken in fitting the body.

Maintaining Classic UK Minitrix Locos
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