Converting a Graham Farish 08 Shunter to DCC

DCC is a very different method of controlling our train sets and one that seems to polarise opinion. I tried it, because it seemed, after a long absence from the hobby, that there should be an alternative to the traditional DC control with block sections and related wiring. I really like using DCC and have become a bit of an evangelist and in particular in my chosen scale of British outline N gauge. Many of the objections to DCC in British N gauge revolve around problems converting the Graham Farish models which are by a long way the most common rtr models available to us. These problems stem from the design predating DCC by some years and no real inclination by Grafar (in the past) to change that design to a more DCC friendly one.

N gauge has a major size disadvantage (in terms of space for decoders) compared with larger scales but thanks to the small scale decoders from Lenz, Digitrax and ZTC, there is usually a site for the decoder to be found. I have converted in excess of 20 Loco’s now, albeit mostly modern image. Each conversion has had its challenges but I have not been defeated yet. My latest conversion and the one I shall outline here is the Farish 08 diesel shunter. I have used my favourite decoder which is one of the smallest available, the Lenz LE0521A. It includes BEMF (Back emf load compensation for constant speed on gradients) and lots of lighting and function outputs that are unlikely to get used in a class 08 but the motor control is superb.

There are two main elements to any DCC conversion; firstly where it can be fitted and secondly how to insulate the pickups from the motor so we can intercept the signal and direct it to the DCC chip.

The 08 is a small loco but there is still room for a decoder in the loco cab directly behind the window. This does mean you will be able to see the decoder (or rather its insulation) through the window but this was not a problem for me. If you do not like this idea, it would be possible to mill out the metal block at the back of the casting in the cab area. This would be pretty time consuming using a Dremel (or similar) fitted with a carving bit, and would also dramatically reduce the weight of the loco.

Space was not the biggest problem; the main issue in the Farish 0-6-0 chassis (08’s Panniers etc) is that the whole chassis block is live with the power to the lower carbon brush. It is virtually impossible to intercept the power from the pickup wipers and insulate them from the chassis. The top carbon brush is mounted on a plastic moulding and is no problem at all.

I was a bit stuck for a while but a fellow N gauge DCC’er  (Gerry Spencer) came to the rescue with a bit of engineering cleverness. He has devised a way to insulate the outer surfaces of the brass guide for the carbon brush. You must also drill out the hole for the brass guide to 2.9mm to allow for the increased diameter of the insulating material. This allows it to remain insulated from the rest of the chassis but you must insulate the legs of the retaining clip. There is room for a fine wire to be soldered to the retaining clip (please do the soldering off the loco) and to run the power directly from the DCC chip. The other motor connection is again soldered direct to the retaining clip on top but no insulation is required as the bracket is plastic. I highly recommend checking the insulation with a multimeter and that you really have insulated the brush guide from the chassis to prevent accidents.

In this picture you can see the insulated carbon brush guide and the brass clip which I insulated with electrical tape. You can easily lift up the rear of the plastic chassis top and pull out the armature to allow access to drill out the chassis

Power from the rails is taken by the pickups as on the DC loco and delivered to the DCC chip by picking the power from the long bolt running up through the chassis for one pole and directly of the chassis for the other pole; I used the clamped wire that used to connect to the suppression capacitor cut short to solder to.

The wiring is as follows, the Orange and Grey wires from the chip (using the NMRA wiring colour codes) go to each of the motor brushes soldering to the brass clips. That said I used a length of black wire to the lower brush guide so it would not show up from the side of the loco. I also took the opportunity of blacking the pickups with a felt tip pen. The Red and Black wires connect to the top of the long bolt carrying power from the LHS wheels and the chassis carrying power from the RHS wheels. I found the pick ups were not very good at touching each wheel when negotiating curves and turnouts; this was fixed by bending the contacts out a little more.

Before replacing the body verify the installation. Place the loco on your programming track and check the address read back. The default for Lenz decoders is address 3 other makes may vary. Do not power up on the main track until you have successfully got the read back just in case you have made a mistake and you “let the smoke out” of the chip. This is DCC’ers shorthand for destroying the chip.

Once the install has been checked out, I insulated the chip with plastic from a clear plastic bag and black electrical tape. Lenz do not recommend enclosing the chip but you need to do something as the body is metal and could short the chip out. Also the 08 is unlikely to be pulling huge trains or running at 125mph and therefore should not get too hot. Tuck the chip in the side of the cab and refit the body. That’s it you are done!

I have not converted any of the Farish Panniers but the chassis is pretty much the same and should be a similar job. I know Gerry Spencer is considering producing limited quantities of these insulated brush guides. Please contact me through MERG or the NGS for further details.

 Gareth Cutting – 01923 253559 – gareth_cutting@waters.com

 Gerry Spencer – 01476 550301 – gerry@jigerspe.demon.co.uk