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DCC'ing Tomix EF81 with Kato Circuit Board


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Hello All,


Having a break from the kiha 40 build, I looked at dcc'ing a kato dd51. I had not removed the body from the dd51, just looked up on the net about dcc for the dd51 and from what I saw, the loco was not dcc ready, but some had used the circuit board for the ef65 to dcc the dd51. So, I ordered a circuit board. A bit later I got round to taking the body of the dd51 and found that it was already fitted with the same circuit board as an ef65, complete with 8 pin socket! With the ordered circuit board already in the post, I got round to thinking what else I could use it for.


I have a number of Tomix ho models, non of which are dcc ready. Some time ago I got a mint second hand ef81, and with it being a similar shape to the ef65, I thought that swapping the Tomix circuit board for the Kato one should be possible, and am pleased to report it is.


The original board is easy to remove, as nothing is soldered to it. Unplug the wires, remove the clips for the motor connectors (keep the clips), and then unclip the board from the chassis. Next, remove the clips on the chassis that are for holding the original board in place, as the Kato board will sit on top of the plastic dividers each side of the motor. The motor terminals attach to the Kato board by the number 15 on the cutting mat, place the contacts on the underside of the board and use the clips from the original board to secure the contacts in place. The wires from the pickups attached to where number 16 is on the mat.


Also, please note that on the left hand side of the motor, you need to remove some of the plastic in the middle of the divider, this is to allow clearance for the gold coloured component on the left side of the Kato board. Position the board with the underside of the dcc socket (right hand side on board) on the flywheel side of divider. It's tight, but the socket will be clear of the flywheel.

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The board in place, with the motor terminals clipped to the board. The blu tack is temporary!


Unfortunately the original pick up wires are too short to reach the connection on the board, so will need extending a bit.  

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And success! This was testing on dc. Next jobs are to insulate the soldered joints from extending the wires, alter the position of one of the LED's, and fit the decoder when it arrives in the post. I will update as and when...

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20180217_114743_resized_2.thumb.jpg.921b6d0f27e8fc23a00144a13b6c8dc0.jpgDecoder fitted.

I used a thin bit of card glued over the drive shaft as a base to mount the decoder on. The decoder came with attachments for a capacitor. There is a handy cut out inside the body which the capacitor fits in nicely, secured in with a little bit of blu tack. I had to reduce the length of the decoder plug contacts by 1mm or so, as the contacts were quite long and the plug stood a little high, making it awkward to fit the body. 


Now to add the detail parts....


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