Tomwilliams123 Posted February 20 Share Posted February 20 Hi all, just wondering please, if there's a way of converting an old non-dcc Hornby merchant navy to run on DCC just by using a 4 pin decoder? I'm aware that I can run the loco on DCC without a decoder, but would preffer to run with a DCC chip if possible please? Link to comment Share on other sites More sharing options...
96RAF Posted February 20 Share Posted February 20 18 minutes ago, Tomwilliams123 said: Hi all, just wondering please, if there's a way of converting an old non-dcc Hornby merchant navy to run on DCC just by using a 4 pin decoder? I'm aware that I can run the loco on DCC without a decoder, but would preffer to run with a DCC chip if possible please? Same way as you convert any non dcc ready loco. Divorce the track pick ups from the motor and connect those 4 wires to the header you are going to wire in for the 4 pin decoder. Link to comment Share on other sites More sharing options...
Rog RJ Posted February 20 Share Posted February 20 Do not run any locos on DCC if they don't have a decoder fitted. They can overheat and burn out the motor, particularly if they are left stationary. 1 Link to comment Share on other sites More sharing options...
gilbo2 Posted February 20 Share Posted February 20 There are some guides here to have a look through to give you an idea of what's involved, just pick one that's closest to your particular age model design: DCC Conversions Link to comment Share on other sites More sharing options...
ColinB Posted February 20 Share Posted February 20 (edited) Do not use a 4 pin decoder, go for a 6 or 8 pin, that way you have more variety in the choice of decoders. I am assuming the Merchant Navy is the rebuilt type as it is old. You might have difficulty fitting it all into the loco body. On my old ones I put the decoder in the tender and connected it to the loco via a 4 way connector as in Hornby's later locos. If the loco doesn't have a decoder fitted it will buzz on DCC, just like putting on an AC source and as someone said eventually burn out. Edited February 20 by ColinB Link to comment Share on other sites More sharing options...
ntpntpntp Posted February 20 Share Posted February 20 (edited) Does the old model have lights? If not then yes all you need are 4 wires: 2 track pickup wires into the decoder and 2 wires out to the motor. The motor must be electrically isolated from the chassis and pickups as part of converting to DCC. As others have said, DO NOT run a plain DC loco on DCC. Although it is a facility that's built into some systems it's something that fell out of favour probably 20 years ago. It's really bad for small motors especially the coreless types used in some new models. Given the price of a cheap decoder it's not worth the risk. Edited February 20 by ntpntpntp Link to comment Share on other sites More sharing options...
Tomwilliams123 Posted February 20 Author Share Posted February 20 1 hour ago, ntpntpntp said: Does the old model have lights? If not then yes all you need are 4 wires: 2 track pickup wires into the decoder and 2 wires out to the motor. The motor must be electrically isolated from the chassis and pickups as part of converting to DCC. As others have said, DO NOT run a plain DC loco on DCC. Although it is a facility that's built into some systems it's something that fell out of favour probably 20 years ago. It's really bad for small motors especially the coreless types used in some new models. Given the price of a cheap decoder it's not worth the risk. No there are no lights on the loco, would you have a wiring diagram for this please? Link to comment Share on other sites More sharing options...
gilbo2 Posted February 20 Share Posted February 20 20 minutes ago, Tomwilliams123 said: No there are no lights on the loco, would you have a wiring diagram for this please? This may help you..... Decoder wiring Link to comment Share on other sites More sharing options...
Going Spare Posted February 20 Share Posted February 20 The very early rebuilt Merchant Navy loco had a live chassis with a wired link to the motor from the driving wheel pick-ups on only one side so the non-wired pick-ups will have to be isolated from the chassis block and wired to the DCC socket. Link to comment Share on other sites More sharing options...
ModelerXYZ Posted February 20 Share Posted February 20 Red and black are the pick up wires, Orange and grey are the corresponding motor wires. With a little bit of soldering it should be possible. XYZ Link to comment Share on other sites More sharing options...
ColinB Posted February 21 Share Posted February 21 (edited) 2 hours ago, Going Spare said: The very early rebuilt Merchant Navy loco had a live chassis with a wired link to the motor from the driving wheel pick-ups on only one side so the non-wired pick-ups will have to be isolated from the chassis block and wired to the DCC socket. That is not too difficult. Fortunately the later bottom plate with pickups from the later ones fit and I think they are still available. Alternatively just wire to both pickups directly. Remember to file down the chassis pick up pin on the underside of the chassis. You can either take out the weight in the smokebox to make room or wire to the tender. Gets rid of that horrible tender connection but you have to file a hole on the underside of the tender to fit the 4 pin socket. That is if you want to do properly. To be honest you can still run with the live chassis, the motor is isolated so it will still work but getting rid of the live chassis will make it run better. Edited February 21 by ColinB Link to comment Share on other sites More sharing options...
96RAF Posted February 21 Share Posted February 21 There are several Pacific chassis that use the chassis block as a wire. One pick up side is wired thru' and the other side as Colin says the other side pick ups connect to the chassis block via a pin. At the top of the block the pick up runs to one motor brush and a link wire from the chassis block runs to the other motor brush. By using the later lower chassis plate with 2 wires and filing down the pin the conversion is much easier. Link to comment Share on other sites More sharing options...
81F Posted February 22 Share Posted February 22 Just to let you know I have used 4 pin decoders to hard wire non DCC ready locos (but not a Merchant Navy). Indeed I actually prefer them as most of my locos do not have lights (being steam) as there are less no unused wires coming from the decoder which can take up valuable space within the locos body. 1 Link to comment Share on other sites More sharing options...
ColinB Posted February 22 Share Posted February 22 3 hours ago, 81F said: Just to let you know I have used 4 pin decoders to hard wire non DCC ready locos (but not a Merchant Navy). Indeed I actually prefer them as most of my locos do not have lights (being steam) as there are less no unused wires coming from the decoder which can take up valuable space within the locos body. Well if you use the Pecket PCB that takes a 6 pin DCC decoder it takes up even less space and when you sell the loco you can easily convert it back to DC by just inserting a header. I do that with a lot of my locos where space is tight. It also only has 4 connections. Link to comment Share on other sites More sharing options...
81F Posted February 22 Share Posted February 22 1 hour ago, ColinB said: Well if you use the Pecket PCB that takes a 6 pin DCC decoder it takes up even less space and when you sell the loco you can easily convert it back to DC by just inserting a header. I do that with a lot of my locos where space is tight. It also only has 4 connections. Funny you should mention that, I have a Bachmann Ivatt 2-6-2T inb bits waiting to receive such a chip, although I am using a harness with a 6 pin socket rather than a Pecket PCB. Link to comment Share on other sites More sharing options...
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