[Trains4U]

Fitting a TCS M1 decoder to a Graham Farish 170.

This guide applies to pretty much any chinese manufactured split chassis Diesel or Electric which is not DCC ready or "DCC friendly"
So, Classes 25/31/33/37(old model)/40/44/45/46/47(old model)/50/52/55/56/87/90/91/158/159/168/170 are covered.



The chassis looks like this:
There are variations between the different models, particularly in frame length and position of the screws.



Remove the underframe detail, this is often held on by one or two screws (Shown) but on smaller locos, this will just pull off.



Before seperating the chassis halves, check and note the position of the bogie mounts. These are a rectangular black plastic piece with two protrusions and a small hole at one end (Small circle)
The bogie fits into an of centre peg,the hole indicates the correct position for the mount. The protrusions fit into one of four sets of recesses.

It is essential that these are put back in the same positions as they affect bogie clearances with the bodywork and whether th driveshafts will fit properly in the motor or not.

In this case, they fit into the outermost of the four recesses, with the hole facing inwards. (I had already undone the chassis at this point, when I remembered to take this pic!)



Undo the screws holding the two chassis sides together - the 170 has two, many have a third in the battery box/fuel tank area.



Carefully remove all components and place somewhere safe.
(There are quite a few component parts)



In order to isolate the motor, it is necessary to remve a chunk of metal from each half of the chassis.
The part to be removed is indicated below. this is a well defined rectangle that is relatively simple and quick to remove.



This can be quickly removed using a decent set of needle files.
You can drill or mill it, but by the time youve plugged your kit in, put the chassis in a vice and selected an appropriate drill, the files would have finished the job.
(Took me about 2 minutes each side)



This is the chassis half with the area cut out



Place the motor in each chassis half and make sure the brass contact of the motor is not making contact with the chassis half. Use a circuit checker to be sure.

Reassemble the chassis ensuring everything goes back where it came from (A three handed job if ever there was one)



A small channel must be cut in each half to accomodate the wires from the motor to the decoder, otherwise the bodyshell will not fit back on.



The decoder wires should be trimmed to the minimum required prior to fitting. Ensure you know where the decoder is going in relation to the body. Some locos may require modifiction to the ribs inside the roof to allow space for the wiring.
Ensure the decoder is not positined where it will foul one of these ribs.

Class 158/159 will require more dramatic modification as the bodyshell is in two parts. The roof must be removed and all decoder wiring passed through a hole drilled above the motor position - then a decoder sized hole cut in the clear ceiling of the main bodyshell so that the decoder will fit with the roof on - all wires are channelled between body and roof as the roof is refitted (A bit of a nightmare)



My preferred method of connecting the red and black ower wires is to secure them using one of the chassis screws and retainers to hold the wires against the chassis sides.

I strip about 10-12mm of insulation off each wire and tin it.



I then wrap one wire around the screw and the other around the retainer, then fit them back in place, ensuring that the wires contact the chassis.

Some chassis will require a channel to be filed to allow the wires to fit flush. this is not the case with the 170 ehre there are cast recesses.



Once the decoder is fitted, test it on the programming track, give it an address and check on the main line.

Position the decoder (Use double sided tape if required - but not a sticky pad as it will raise the decoder too high)
put the body back on, test once more, and its all done.

[Etched Pixels]

For the long DMU stock its a lot easier to put the deocder in the underframe moulding than butcher the roof area. Also if you are using a sound decoder its in fact pretty much essential both to get the needed height and so any speaker wires to the other car are low down and won't make the unit topple on curves.

[russellwar]

Does this method work for 37/47's etc?

[Edwin_m]

russellwar, on 28 October 2009 - 19:36 , said:

Does this method work for 37/47's etc?

I've done a 47 (not the new version released in the last year or so) and the OP says the older version of the 37 is similar too.

I don't bother with the channels in the chassis as I've found you can run the orange and grey wires up between the two halves of the chassis without fouling anything. This also helps with the 158 as you don't have to remove the inner roof right out to the edges.

[David Rickard]

This guide is spot on what I wanted!

Now to get some decoders.

[David Rickard]

I converted a GraFar Class 168 yesterday and it worked fine. However, I was wondering if it's worthwhile making a slight modification to the power pickup. Out of the box it uses the little copper arms to contact with the main block. I've soldered the power feeds for the DCC module to the top of these blocks (having roughed them up a bit). However, one of them came adrift once and I don't really hold out much hope for it long term. I wasn't too keen on running the feed wires around the screw as there's a lot of paint there to try and clean up to get a good contact.

I'm wondering if it's worthwhile running a couple of small wires between the bogie pickups, then joining the DCC controller to that, totally bypassing the ballast blocks entirely. Surely they add a fair bit of resistance? Or maybe they're meant to! I'm just curious as to if it's worthwhile. I think it might make things more reliable overall.

[Edwin_m]

I've never had problems with the copper strips that rub on the chassis - those that rub on the wheels are more likely to be a problem. Although the chassis block probably doesn't have the same conductivity as the copper, its cross-section is so much more that I suspect its total resistance is pretty close to zero.

[Etched Pixels]

I solder fine decoder wires direct to those little strips on the old CO-CO and DMU chassis as over time they get oily and also in heavy use can wear a bit. Not sure its a big win but its less potential future maintenance work. The BO-BO chassis has a much more sensibly designed bogie-chassis power transmission and doesn't need this.

(Another reason to do this of course is that short of a chemistry exercise you can't solder to the metal blocks on the chassis, so it eliminates another weak point).

[David Rickard]

Etched Pixels, on 21 December 2009 - 12:21 , said:

(Another reason to do this of course is that short of a chemistry exercise you can't solder to the metal blocks on the chassis, so it eliminates another weak point).

That being my overriding concern. I think I might give it a whirl. I've got some nice fine wire suitable for it. I'll let you know how I get on.