37lover Posted January 15, 2020 Share Posted January 15, 2020 I have only previously used 4 pin and 8 pin decoders but a recent thread about the Stephenson's Rocket discussed the 6 pin socket/decoder. The only pictures I've seen suggest 2 wires from the pick-ups and 2 to the motor, leaving two others [neither of which appears to a common] which eventually connect back to the motor return. The return surely is AC? So do the two extra wires each provide a separate additional function?I assume where space is a premium the 6 pin provides a compromise between the 4 pin "motor only" and the 8 pin "4 function" decoders.As an aside what could the extra 2 functions be used for on the Rocket? Oil lamps, firebox flicker? Link to comment Share on other sites More sharing options...
Howbi Posted January 15, 2020 Share Posted January 15, 2020 @37L...........the R7150 6 pin decoder is the same as the R8249 without the Blue & Green wires attached........the Yellow & White wires are used for front and rear lights (as per usual DCC convention) or even FB flicker with the return to the pick-up Black wire........HB Link to comment Share on other sites More sharing options...
96RAF Posted January 15, 2020 Share Posted January 15, 2020 From that I would suggest if blue (for lights power say) is needed it is taken from the track and regulated by the loco pcb or if DIY by a discrete added component. Link to comment Share on other sites More sharing options...
Chrissaf Posted January 15, 2020 Share Posted January 15, 2020 The Yellow & White wires are used for front and rear lights (as per usual DCC convention) or even FB flicker with the return to the pick-up Black wire........HB.Sorry to butt in so drastically but HB is mistaken and I wouldn't want someone to follow the advice and damage their decoders. The black wire should not be used as a lighting return wire without additional diode modification. The black wire is a wheel pickup and connecting that directly to any of the lighting circuits is likely to damage the decoder, due to it being 28 volts peak to peak AC..As intimated by Rob, when using any NMRA 6 pin decoder, the positive return (aka the blue wire function) has to be generated away from the decoder. For models that are factory fitted with lights and a 6 pin socket this positive return wire function is usually built into the loco PCB..But where lighting is an after market 'afterthought' on a loco without factory fitted lighting and with a 6 pin decoder socket, two diodes need to be DIY added as part of the lighting installation. The diodes convert the 'peak to peak' 28 volt AC [bi-polar square wave] to a pseudo 14 volt DC that is more compatible with the decoder function circuits..The connectivity is simple enough and the drawing schematic below shows it. In the schematic below you only need to focus on the two diodes connected to the black and red wires that generate the function of the blue positive return wire. The schematic was originally drawn for a full directional lighting installation, but could easily be modified for oil lamps or a fire glow. But note that the two 6 pin decoder functions are firmware configured as F0 directional lighting and not as a general use pair of functions. Thus there would be functional limitations using these for a fire glow../media/tinymce_upload/2e3b617b7ac6a39dd682a50c0943625f.jpg. Link to comment Share on other sites More sharing options...
37lover Posted January 15, 2020 Author Share Posted January 15, 2020 howbiman,Thank you for responding and I do not wish to do you a dis-service but the responses from Chrissaf and Raf96 demonstrate why I asked, easy to get it wrong! Link to comment Share on other sites More sharing options...
Howbi Posted January 15, 2020 Share Posted January 15, 2020 Absolutely, 37L, Chris & Rob can always be relied upon to spot & correct our mishaps....... 😳....HB Link to comment Share on other sites More sharing options...
Chrissaf Posted January 15, 2020 Share Posted January 15, 2020 Bumping post to bring to 37L attention that I have heavily editied my reply since his last timed post. Link to comment Share on other sites More sharing options...
37lover Posted January 15, 2020 Author Share Posted January 15, 2020 Many thanks, duly noted. If I am successful with my order for the Rocket I will now be restricting any use to a simple 6 pin decoder for operating the motor only. Link to comment Share on other sites More sharing options...
Fishmanoz Posted January 15, 2020 Share Posted January 15, 2020 Given the info above, one might wonder why they've put a 6-pin socket in the Rocket in the first place. And just which locos they wil include the diodes in to use the lighting functions? Link to comment Share on other sites More sharing options...
96RAF Posted January 16, 2020 Share Posted January 16, 2020 As far as I know Fishy none of the DCC6-Ready locos have lights but I would expect the loco PCB (if any) to have the diodes built in. We have seen such diodes built into some 8-pin blanking plugs. /media/tinymce_upload/ab1eb25fbdfcbda97cb2c499a994ac26.JPG Link to comment Share on other sites More sharing options...
Fishmanoz Posted January 16, 2020 Share Posted January 16, 2020 But why go to the trouble if no lights? Link to comment Share on other sites More sharing options...
ColinB Posted January 17, 2020 Share Posted January 17, 2020 If you do want to fit lights, then use one of the other 6 pin DCC decoders, some of them come with the blue wire on a flying lead, making it much easier. The one thing you might need with the rocket is KAM as there are not many wheels to pick up the power, unless Hornby are going to use the tender wheels as pickups. Link to comment Share on other sites More sharing options...
walkingthedog Posted January 17, 2020 Share Posted January 17, 2020 I should think they will use the tender, might use the coaches as well. KAM?? Link to comment Share on other sites More sharing options...
ColinB Posted January 17, 2020 Share Posted January 17, 2020 Sorry forgot not working on cars, KAM - Keep alive memory, should have read stay alive memory. A big capacitor that helps the DCC keep its supply over dirty track ( a very simplistic description). Link to comment Share on other sites More sharing options...
walkingthedog Posted January 17, 2020 Share Posted January 17, 2020 Ah right. I know what stay alive is. Link to comment Share on other sites More sharing options...
Chrissaf Posted January 17, 2020 Share Posted January 17, 2020 I would think it is actually "Keep Alive Module" not memory. Link to comment Share on other sites More sharing options...
96RAF Posted January 17, 2020 Share Posted January 17, 2020 In automotive context it is memory as it is one of those 9v clip ins that hold your radio and other codes if you have to disconnect the battery. Some companies have registered the names Stay Alive, Keep Alive, etc so the term ends up a bit like Hoover meaning any vaccuum cleaner not just the branded one. How about track voltage reservoir assist module for a DCC decoder. I couldn’t think of a longer winded name. Link to comment Share on other sites More sharing options...
ColinB Posted January 17, 2020 Share Posted January 17, 2020 Actually in automotive, at least for Ford it is Keep Alive Memory, as it keeps the memory powered even when the ignition is off. It is more relevant for RDS radios where you need to keep a lot of data in memory and EEProm is too expensive. It is also used in the engine control module to remember important data, that is why if you disconnect the battery the car runs really rough for a little while. I suspect it is used in a lot of other modules but they were the only two I worked on. Link to comment Share on other sites More sharing options...
37lover Posted January 17, 2020 Author Share Posted January 17, 2020 But why go to the trouble if no lights?I have asked Hornby why they have fiited a 6 pin rather than 4 pin and what do they suggest the "extra" functions are used for. I will post their response if/when received. Link to comment Share on other sites More sharing options...
Rog RJ Posted January 17, 2020 Share Posted January 17, 2020 Maybe they've had too many complaints about the 4 pin decoders being non standard, unlike the 6 pin decoders. Link to comment Share on other sites More sharing options...
37lover Posted January 17, 2020 Author Share Posted January 17, 2020 Rog(RJ),Do you think I should start a sweepstake on what they'll say? I think you would have a good chance of being right but unlikely to be acknowledged. We shall see [hopefully]. Link to comment Share on other sites More sharing options...
Rog RJ Posted January 17, 2020 Share Posted January 17, 2020 😆 Link to comment Share on other sites More sharing options...
Traincliff Posted February 18, 2020 Share Posted February 18, 2020 Hi. I have read through this thread having found it through a SEARCH and as it is fairly recent and partly answers my query I thought it sensible to resurrect it. On a You Tube stream I had on in my shed while modelling I thought I heard a statement that you should be aware that you have to use Hornby 6pin decoders in their locos as they have configured them differently to other manufacturers. In these days of NMRA standards I would be surprised at that and this thread does not indicate deviation to me. I don't normally buy Hornby decoders at the moment but would if I really have to. One loco I do have to chip is my little Ruston diesel but was planning to use a DCC concepts decoder. Would appreciate "learned" comments please in case I have missed a point somewhere.Cliff Link to comment Share on other sites More sharing options...
Chrissaf Posted February 18, 2020 Share Posted February 18, 2020 Traincliff,Rob (RAF96) subsequently to this thread posted information provided by Hornby tech support regarding the 6 pin decoder for the Rocket. You can read his post here:.https://www.hornby.com/uk-en/forum/decoder-for-the-rocket/?p=1.The way I read his post is that any 6 pin decoder used in the Rocket must come on a harness due to the way that it is physically fitted (the Hornby version comes on a harness, hence why the documentation recommends it)..Many other brands of 6 pin decoders have the 6 pin connector as an integral part of the decoder, therefore would not be suitable due to a physical fitting requirement. Any 6 pin decoder brand that comes on a harness should, in theory, be suitable.. Link to comment Share on other sites More sharing options...
Traincliff Posted February 19, 2020 Share Posted February 19, 2020 Thank you Chris. I think that clears up confusion for me. The ongoing discussion was indeed about the Rocket but gave impression the same applied to other Hornby 6pin locos. The later post did not come up in my Search. Thanks to you, Rob and Hornby Forum for clarification as always. Don't have any of these concerns when working on Triang stuff - I just dive in and do it lol.! Link to comment Share on other sites More sharing options...
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