I`m trying to convert a Hornby Intercity 225 to DCC. The problem is that the ringfield motor type 6 only has one visible wire which is brown and this goes from the the rear bogies to the clip on the motor terminal which is on the front bogies. There are no other wires on the motor. It does not seem to be like any of the examples found on the internet.How do I put a dcc chip on this motor? Any help greatfully received. Please bear in mind I am not an electrician so please could you keep the answers really simple.
The motor is grounded to the frame of the front bogie. IOW, the whole bogie acts as a pickup. The current path is: front bogie --> motor --> rear bogie. One bogie picks up power from the right rail, the other from the left rail, but I can't recall which does which. Not that it matters.
IIRC, the motor frame and front bogie frame are one piece. If that's the case, you can't install DCC, since the motor must be insulated from the bogie frame. OTOH, if the motor is bolted to the frame, you can insulate it using plastic bushes and washers, and larger holes for the bolts. You'll also have to manufacture a pickup to wipe against the back of the uninsulated wheels on the front bogie, and install a wire from it to the decoder. Not a job for the fainthearted. ;-)
DCC current path is: right pickup --> decoder --> motor --> decoder --> left pickup.
The basic DCC wiring is: right and left pickup wires to the decoder, and then the two wires from the decoder to the motor.
OK, that's the overview. If anyone has actually done the conversion, they can fill in the details. And you know what they say: the devil's in the details.
One bogie is earthed +ve the other -ve. Looking at the motor bogie from the side with the brush retaining arms, you need to isolate the left hand brush arm screw from the metal frame of the bogie. The easiest way is to use a nylon screw in place of the original metal screw.
Once that's done you need to take a feed from each bogie to the deoder black & red wires, and then take the outlet wires (grey & orange from memory) direct to the brush retaining arms.
I believe the American company Kadee produce some - you should be able to source these from M G Sharp Models in Sheffield. Don't ask me the size or part number though. I can't find my pack.
Have just got a reply from M G Sharp models. They only do 1 sort of nylon screw and this is acetal 2-56 x 1/2 inch. Does this sound about the right size for the left brush arm retaining screw ?
I've not seen the model, but from information given:
You have a US bolt specification (UNC). The bolt size 2-56 is 0.086in diameter or 2.2mm (The "2" refers to its diameter via an odd formula, and the "56" is the teeth per inch).
1/2 inch refers to its length. Obviously can be cut down to length.
I'd guess that the Hornby has either a BA or Metric screw thread ?
If its close in size, and has to go into a metal hole, you may get away with forcing the "wrong" thread into the hole, cutting a revised thread shape.
Alternative is to make a plastic bush to insulate the arm from the screw - a tiny sliver of tube (drinking straw ? plastic flexible pipe ?) and some paper soaked in superglue as an insulating washer should do the job. Then open the hole in the brush arm a little to allow those to fit through.
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