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DC To DCC Tender Drive?


cornishmick

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Hi i have a few tender drive locos ie KIngs A1s ect and im looking to convert them from DC to DCC but am unsure what to do or where i put the decoder as they are not dcc ready but are great runners on full speed and low speed could anyone please tell me how to wire the decoder and what wire goses where and also where i have to fit the decoder as i am new this and i have found some great stuff on this site would be glad of any help

 

mike :O

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Hi Mike

 

DCC decoder installation is relatively straightforward in principle, whether loco-drive or tender-drive. You have to ensure the motor is completely isolated from the track pickups - otherwise your decoder will be damaged, probably fatally.

 

You need a decoder that just has wires, not any sort of plug on the end. Four wires - there may be 9 or more, all different colours - should interest you. The red and black wires go to the pickups, the orange and grey wires go to the motor. All that should be confirmed on the instructions you get with your decoder. Read them right through before doing anything.

 

And that's it!

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Hi Mike

 

DCC decoder installation is relatively straightforward in principle, whether loco-drive or tender-drive. You have to ensure the motor is completely isolated from the track pickups - otherwise your decoder will be damaged, probably fatally.

 

You need a decoder that just has wires, not any sort of plug on the end. Four wires - there may be 9 or more, all different colours - should interest you. The red and black wires go to the pickups, the orange and grey wires go to the motor. All that should be confirmed on the instructions you get with your decoder. Read them right through before doing anything.

 

And that's it!

 

 

Thank you for that will keep u all poted on hw i get on :declare:

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Just keep an eye out for those Hornby tender drives where one of the brush holder retaining screws is live to the rail and needs to be insulated - if I hadn't know about this I'd have blown a decoder. You should be able to tell if it's one of those by tracing the electrical path to the brushes.

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Yes watch out for that brush holder screw, its usualy the left hand one. Have only had one of these in the past, swopped the backplate for an older type that has bend up brush holders, not the screw type. Later motors caused no trouble, not easy to identify.

so check the electrical path.

To get the best running with these motors its my experiance that a 5 pole motor is far better than a 3 pole. A 5 pole armature will NOT replace a 3 pole armature. You can fit a 5 pole motor assembly in place of a 3 pole. Not cheap about £ 25.

To get the absolute performance from a tender drive, its imperative you use a good decoder. ( cheapies will not do) I have 6 tender drives. A3 & A4s. 5 pole motors with Zimo MX 621. & MX 630. Decoders. At step 1 they just crawl, and no jerking. Do remove the capacitor across the brush holders, otherwise you will get all sorts of funny reactions. Keep us posted.

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Oddly enough, and not to contradict the above, I've got very good results with the basic Hornby decoder in 3-pole Hornby and Airfix-style tender drives. I tried a Bachmann one in the tender of a Margate era 9F and no amount of fiddling with the CV settings produced acceptable smooth starts and slow running. Bung in a Hornby one, and the performance was outstanding from the outset with no tweaking. I've also had similarly good results in 4Fs and 2Ps using the same decoder.

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Re my post. Fit a good decoder. I suppose with the advancement in decoder technology its possible to get the smooth running as a previous post has remarked on. From my own point of view I always fit a top end decoder even to the latest Locos. and always the same make. But thats as I said is a personal decision. Do let us know how you get on. Regards.

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  • 1 year later...
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Oddly enough, and not to contradict the above, I've got very good results with the basic Hornby decoder in 3-pole Hornby and Airfix-style tender drives. I tried a Bachmann one in the tender of a Margate era 9F and no amount of fiddling with the CV settings produced acceptable smooth starts and slow running. Bung in a Hornby one, and the performance was outstanding from the outset with no tweaking. I've also had similarly good results in 4Fs and 2Ps using the same decoder.

Hi Barry Ten, I wondered if you knew if you knew if the basic Hornby decoder worked well with the 5 pole tender drive motor too. Tom

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Hi Barry Ten, I wondered if you knew if you knew if the basic Hornby decoder worked well with the 5 pole tender drive motor too. Tom

 

I fitted one in a 5-pole tender drive 28xx and it performed well.

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One of 2 possible solutions for isolating the Hornby Motor terminal from the chassis:

Buy a pack of Nylon screws of the the same or similar size (ie correct diameter) and replece the metal screw with one of these, thus achieving the required isolation.

(If the thread does not match precisely - because it is soft nylon, it will 'adapt' itself - I know it sounds crude but it does work)

 

The other method I used to use was to use insulating tape tofully insulate the tab - enlarging the hole, and ensuring that the insulating tape occupied it - so NO metal could ever come into contact with other metalwork.

 

The worst motors to convert, in this respect, are the 'white' Mainline or Bachmann motors which use 'long tabs' of metal which make contact on either side of the split chassis - without 'wires'

Back in Zero-1 days, when I originally made these conversions, I had to repeat the process a few weeks later, when Hornby decded to 'reverse' which polarity was 'forward', after their MD (apparently) commented on Tri-ang (Hornby) locos running backwards, when everyone else's ran forwards .... due to which rail the chassis was 'Live'.   I had to flip the magnets in my Hornby-Dublo Ringfield locos as a result!    This represents one of the fundamental differences in philosophy between Zero-1  and modern DCC: Zero-1 was a 3-wire conversion, and all modern DCC systems are 4-wire: the motor is TOTALLY isolated from the track, with the decoder inbetween. [Another fundamental difference being backward compatibility to analogue running capability with a decoder-fitted loco, and finally the commonality of decoder - independant of local mains frequency - Zero-1 had 50 Hz and 60Hz versions]

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