DCC Loco Conversions - 34 - Dublo Co-Co (Deltic)

I have two Co-Co locos D9012 Crepello and D9014 (a re-bodied plain green Co-Co) to which I fitted two different RoS decoders in an effort to make a cleaner installation, however the design of these locos makes this difficult. Anyway, both methods are shown.

Very Important - the motor bogie was modified as in article 33, failure to do so can destroy a decoder.

https://platform1mrc.com/p1mrc/inde...dublo-ringfield-motor-bogie-co-co-co-bo.6156/

All original wiring replaced due to the usual poor standard of assembly and suppression parts removed, I rely on the electrical isolation between motor and track provided by the decoder.

Loco 1 : D9014

The first loco to be converted D9014 was initially fitted with an 8 pin socket to try out a RoS-6D, (or a Gaugemaster decoder if necessary), loco current consumption similar to the 2-6-4T locos, but as there was space I fitted a RoS-218 which is physically larger but has a cable harness which makes installation a little easier to wire.

Wired with 10/0.1 PVC insulated wire.

Flexible sleeving to protect wires passing through the mounting plate.

Decoder attached to the mounting plate which joins the two bogies with a double sided sticky pad and a wrap of Kapton tape across the 21 pin socket, the wiring routed to avoid being trapped between the mounting plate and the body shell.

Unused wires on the harness cropped saw tooth fashion at the connector.



Routing of wiring between bogies.





At the motor bogie, the grey wire connects to the tail of the retaining pin and the orange to the brush plug opposite.






During initial testing on the layout the loco slowed to a halt due to the carbon brush rotating the brush spring such that it screwed itself past the retaining pin on the newly insulated brush holder.

To avoid this happening the retaining pin must not be inserted through the helix of the spring on assembly, the end of the spring must bear against the pin.

After correcting my assembly error D9014 ran well again.


Loco 2 : D9012 Crepello

Not particularly happy about the physical arrangement of the decoder and wiring on D9014 so on this Co-Co I have fitted a RoS-6D to the un-powered bogie with a packing piece and double sided sticky pads.

Wired with 10/0.1 PVC insulated wire.

Flexible sleeving to protect wires passing through the mounting plate.

Wires lap jointed onto the decoder pins, reinforced by shrinking heat shrink sleeving over the joints, unused decoder pins cropped off, extra sleeving around orange and silver wires to prevent abrasion from mounting plate.



Routing of wiring between bogies.





At the motor bogie, the grey wire connects to the tail of the retaining pin and the orange to the brush plug opposite.





Setting Up the Decoder

A nominal start voltage setting of 14 was required for D9014 (0 for D9012) as backlash in the gear train caused some juddering by upsetting the BEMF response, however the lowest low speed running is acceptable and it runs smoothly once rolling.

Summary

The second conversion (D9012) with the RoS-6D looks neater and stronger, as sticking the RoS-218 to the underside of mounting plate may not last too long on D9014 due to rust on the plate. May well reinforce this with lacing cord tied fore and aft around the decoder.

The Co-Bo locomotive is a very similar loco to convert so a potential third method of installing a decoder in a Co-Co can be seen in the Co-Bo conversion article.


Discussion always

Jim

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Hi Keith.

Certainly a good alternative, I used nylon reinforced lacing cord as I had it to hand and is more flexible than cable ties I have, although I must admit it is somewhat fiddly trying to tie reef knots in confined spaces

Jim

 

Added note "Setting Up the Decoder".

Wear and gear train backlash can be an issue when using BEMF on vintage locos.

Jim