Wednesday 12 December 2018

Lima XPT

Thought these are now getting old the XPT is still popular as it offers a cheap Australian look alike.

It was decided to install a Lasic decoder with stay alive as they are a good cost match to the locomotive. The installation is straightforward as the motor pickup is clearly located on the motor.

Begin by removing all the existing wiring for the motor and lights as these will be upgraded to LED as part of this conversion.

DCC is very sensitive to pick-up and the basic pickup originally supplied with these locomotives has to be improved, this is done in two ways, firstly the front bogie is rewired and upgraded and secondly a stay alive was added.

Fixing locomotive weight

Modification to front bogie consist of hardwiring to the factory pickup

Lower clip is released and the working face cleaned and tinned, a feeder wire was soldered  and a hole drilled to allow it to pass through the bogie frame 

Note: ensure that the exit point does not foul on the pickup of the assembly

A hole is drilled through the frame to allow connection to the tab, next the tab was fixed over the pin by pushing it over the pin and then lifting the pin to engage in a groove located on the pin.

Decoder installation - the grey & orange arranged as shown allowed
fwd to operate correctly

Decoder and Stay Alive Installation

In the image above note the heat shrink, this contains a pin/socket that allows the stay alive to be disconnected for programming - this proved to be an issue with this decoder.

LED headlight

A LED installed replacing the rather clunky headlight original installed. To do this the cover was removed from the chassis and a LED module incorporating the LED and resistors, it was fixed with contact cement to the locomotive cover and once dry the refitted to the chassis.

Cutout to clear decoder

At assembly, the perspex fouled the decoder but a quick trim allowed a neat fit and finally the hood to be reinstalled.

With a small amount of adjustment and clean wheels, it moved off with as much grace as these units are capable of.

All items used in the installation are available from the MRRC.

Wednesday 5 December 2018

21 pin Stay Alive

This blog covers wiring a stay alive to a 21 pin TCS decoder but is applicable to all decoder conforming to the 21 pin standard

TCS do not recommend soldering onto the decoder

Using the attached image solder the black [earth pin 20] and blue [positive pin 16] onto the pin of the adaptor board. When finished ensure that no balls or solder bridges are present as the SD card slot resets are close to these pins.

If the 12 volt comes into compact with the blue pin comes into contact with the SD card slot will send 12V to ground and will cause arcing/sparking that will destroy the decoder.

Use of Kapton tape across the pads is recommended.

Note: Do not use additional KeepAlive devices in parallel with the TCS motherboard.

ESU provide a basic adaptor board for this installation - click here