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Graham Farish split chassis - DCC guide





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#1 Trains4U

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Posted 11 October 2009 - 17:48

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.

far1.jpg

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

far2.jpg

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

far3.jpg

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!)

Far5.jpg

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

far4.jpg

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

far6.jpg

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.

far7.jpg

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)

far8.jpg

This is the chassis half with the area cut out

far9.jpg

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)

far10.jpg

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.

far11.jpg

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)

far12.jpg

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.

far13.jpg

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.

far14.jpg

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.

far15.jpg
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#2 Etched Pixels

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Posted 28 October 2009 - 18:59

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.

#3 russellwar

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Posted 28 October 2009 - 19:36

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

#4 Edwin_m

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Posted 28 October 2009 - 20:41

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.

#5 David Rickard

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Posted 16 November 2009 - 20:56

This guide is spot on what I wanted!

Now to get some decoders.

#6 David Rickard

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Posted 21 December 2009 - 10:02

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.

#7 Edwin_m

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Posted 21 December 2009 - 12:00

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.

#8 Etched Pixels

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Posted 21 December 2009 - 12:21

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).

#9 David Rickard

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Posted 21 December 2009 - 12:47

(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.

#10 FCC 321401

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Posted 02 April 2011 - 19:29

Is there any alternative, cheaper decoders that could be used? I'm a bit short of money at the moment!

#11 Etched Pixels

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Posted 02 April 2011 - 19:50

Most of the N gauge decoders will fit nicely. That said at about £21 the TCS is one of the cheapest actual N sized decoders with wire harness.

You can in theory use the Bachmann 6 pin one but you'll need to either do some quite fancy wiring to the pins or wire a socket too, at which point it might save you £4 and won't work on DC.

#12 Edwin_m

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Posted 02 April 2011 - 19:52

The depth of the decoder is critical unless you plan to mill out a piece of the chassis. The space available under the roof varies between the different models but is small on most of them. May be a good idea to make a block of Plastikard to the correct dimensions for the decoder you are interested in, then stick it temporarily to the chassis and see if the body goes back on properly.

If the dimensions are OK I'd look at the Digitrax DN135 only from Digitrains, or failing that the DZ125 from most suppliers.

#13 Etched Pixels

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Posted 02 April 2011 - 20:49

For the 158/170 etc don't put the decoder in the roof as the guide suggests put it between the bogies where there is plenty of room for most N decoders

#14 Bandit

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Posted 28 April 2011 - 16:48

I have just converted a Class 91 which is very similar to this.

All went well and the engine is now running fine on DCC.

Unfortunately there is now a lot of noise from the engine which I eventually found to be the motor vibrating. It seems that the motor would have been held firm by the portions of the frame which have now been removed.

Has anybody had the same issue and found a simple solution to this problem?



#15 Edwin_m

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Posted 28 April 2011 - 20:31

I've done a 47 (pre-2009 version) and several 158s and 170s. All were still very quiet after conversion, but I didn't have to remove any of the chassis apart from the small parts over the two brushes. Have you had to remove more on the 91? Also have you fully tightened the screws and included all the spacers - there's probably supposed to be one underneath the motor?

#16 mjkerr

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Posted 28 April 2011 - 22:12

The Class 91 uses a completely different type of chassis
Take the body off one and take a look
The normal method with this is to strip, isolate, and rebuild
The pickups are then used instead of the chassis

#17 roundhouse

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Posted 29 April 2011 - 04:48

Is there any alternative, cheaper decoders that could be used? I'm a bit short of money at the moment!


I am using Hornby decoders in Farish class 168's. Need to file a section on top of the chassis so it clears the roof of the body shell but at around a tenner the filing of the chassis is worth the effort.
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#18 mjkerr

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Posted 29 April 2011 - 08:58

Don't use the cheapest decoder, use the most appropriate
In N gauge my preference is the Digitrax DZ123 / DZ125
Where a 6 pin socket is fitted I use the Bachmann 36-558
Both cost between £12 and £16

#19 Edwin_m

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Posted 29 April 2011 - 09:01

The Class 91 uses a completely different type of chassis
Take the body off one and take a look
The normal method with this is to strip, isolate, and rebuild
The pickups are then used instead of the chassis


Are you referring to the Poole-built version? As I understand it, and as implied by prevous posts, prior to the introduction of the PCB/DCC version with the Class 66s all the China-built D&E models except the 08 and the 20 used variations on the same split chassis concept.

#20 mjkerr

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Posted 29 April 2011 - 10:21

Are you referring to the Poole-built version?

Yes, I too thought this would be a similar chassis, however on opening up it completely different and seems to be unique to the Class 91

#21 Bandit

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Posted 29 April 2011 - 14:14

This Class 91 is China built.
Here is a picture of another identical one which i also need to convert to DCC.
I will try to resolve the issue with the first today.

Class91.JPG

#22 Edwin_m

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Posted 29 April 2011 - 15:15

That picture confirms the China-built Class 91 is of similar construction to the other split-chassis China-built locos featured in this topic. I guess the lower roofline for the pantograph means there is no room on top of the chassis, and the chassis itself also takes up most of the space between the bogies. Is there room for a small decoder in the blunt end cab? If necessary you could look at something like a Zimo MX621 or a CT decoder, both of which are very small and have an excellent reputation, but will cost more than the likes of Digitrax.

#23 Bandit

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Posted 29 April 2011 - 15:40

I have already converted to dcc using a TCS M1 decoder which fits nicely in the roof to the front of the pantograph with room to spare.
Having checked that the engine was put back together correctly i have come to the conclusion that i may have distorted one or both sides of the chasis while filing away the two parts over the brushes.
There is a little play at one side of the motor. the chasis not coming together perfectly.
I will have to take more care with the next one.
Aside from the noise from the vibration the conversion using this method was fine.

#24 Etched Pixels

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Posted 29 April 2011 - 18:46

The metal is fairly soft but can be gently coaxed back into shape if need be (or slip in some thin packing shims of paper)

#25 Kev48

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Posted 01 September 2014 - 19:24

Has anyone managed to do a class 90. I am struggling to find space, even by milling out some of the chassis because the inside roof of the body is very low.

 

Am using a DZ125 chip









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