Pictorial Graham Farish Class 50 DCC Conversion Hornby Decoder

[dripfedfred]

This is a pictorial history of a Graham Farish class 50 dcc conversion I did recently. In the past I have used smaller digitrax decoders but on this one I was able to find room for a Hornby R8249. It worked out very well. I've done a few more since and discovered that the running characteristics of this type of split chassis work well with this essentially budget decoder. It wont fit into most of the newer Farish "solder tab" dcc ready locos, or the DMU models which have shells that hug tight to the chassis but it will fit into most of the standard China split chassis models. A little milling of the shells plastic cross beams is sometimes necessary to make space for the decoder wires lying over the top of the chassis but this kind of decoder frequently fits easily into the upper shell above the cross beams. I filmed a test run of the loco which can be found here http://www.youtube.com/user/DStewart1011?feature=mhum#p/u/2/ItmPiBsOms4. Quite impressive particularly on slow running. The only modification to the standard settings on the R8249 was a small extension to the acceleration and deceleration curves, apart from that its just the way it arrives.

 

The pictures show the way the conversion was done. The second shows the milled out pieces of chassis to isolate the motor and the rest is just straightforward re-assembly with cutting and soldering of the decoder wires. The new pickup connection to the chassis for red and black wire connections from the decoder is constructed from 1 mm copper wire force fitted into a cut across both sides of the chassis.

 

1 Loco stripped2 Chassis halves modified for isolation of the motor. You can just see the lugs milled away where the motor sits3 Re-assembly4 Re-wired to test the isolation on dc before fitting the chip5 Chip seated with wires cut to length and tinned6 Wires connected to isolated motor terminals and new chassis pickups7 Complete

 

Douglas

[bcnPete]

Thanks for posting this - very helpful...especially as I look to soon start swapping my 2mmFS stock from DC to DCC....the Farish 50 being one of them

[Kris]

When I converted my 50 I did it in much the same way (using a different chip). What I also did was to create a small channel coming up from the motor area on the chassis to make the wiring neater.

If you have issues attaching the wires to the chassis blocks the drilling and tapping the holes to allow small screws to be added works.

[Edwin_m]

I've found you can just reverse one of the two screws that hold the chassis halves together, and put the red and black wires under these as you tighten the screw. This makes good electrical contact with the chassis without having to do any more drilling. I also run the orange and grey wires between the chassis halves rather than outside, which seems to work OK as long as you make sure they can't foul the armature or other moving parts.

[Mr.S.corn78]

HI all,

 

a nice looking install, couple of points/suggestions to help people out after chipping a few of these.

 

1) as has been mentioned make a couple of small channels to stop the wiring pushing the body out at the sides and also reduces the risk of stripping the insulaltion off the wire.

2) DONT wrap the decoder, it states this in the instruction sheet for the R8249 decoder and by wrapping it it increases the risk of it over heating and cooking it's self.

 

cheers

Simon

[dripfedfred]

Couple of very interesting points for debate:

 

It is very true that filing of some channels for the decoder wires is necessary to gain a clean refit for the shell on some models of this type. This one did not fall into that catagory however. It is interesting that the R8249 is supplied with fine decoder wires and this has helped. I have converted a number of this chassis type with Digitrax dz125 and dz123's and you nearly always need to cut channels as the wires are somewhat thicker.

 

On the point of wrapping the decoder in insulation I have never found problems in doing this with OO gauge models so it is debatable. The data sheet supplied with an R8249 does clearly state that you should not wrap the decoder for the very reason mentioned but the picture tutorials listed on Hornby's website appear to contradict this. I have always compromised on this aspect by very loosely wrapping the decoder leaving it open at both ends as, first insuating the decoder, prevents static from handling during the installation. Having said that, n gauge shells are tighter so it may be more of an issue in terms of heat build up

 

Douglas

[Mr.S.corn78]

Couple of very interesting points for debate:

 

On the point of wrapping the decoder in insulation I have never found problems in doing this with OO gauge models so it is debatable. The data sheet supplied with an R8249 does clearly state that you should not wrap the decoder for the very reason mentioned but the picture tutorials listed on Hornby's website appear to contradict this. I have always compromised on this aspect by very loosely wrapping the decoder leaving it open at both ends as, first insuating the decoder, prevents static from handling during the installation. Having said that, n gauge shells are tighter so it may be more of an issue in terms of heat build up

 

Douglas

 

hi,

 

I totaly agree, it dosn't help when you have the website and also the DVD that they did with BRM showing that you wrap it.

 

I do decoder fitting for a local shop and have about 30+ decoders that people have fitted and cooked due to wrapping so it may be a luck thing. :-)

 

cheers

Simon