Hi ,Just got my K27 and i have installed a QSI decoder,On the Bachmann board there is three switches ,i need to know position of second switch NMRA std OR LARGE SCALE
Bachmann K27 DCC setup info
- Thread starter nico
- Start date
nico said:
Hi Nico
Not sure what my K-27 is set on think it is large Scale, but the difference between NMRA and Large Scale is the track power + & - , so if you change the switch it changes the + & - to - & + . NMRA stands for National Model Railroad Association.
nico said:
update of what the switch is for
Track Polarity Switch (middle): In Large Scale, there are two conventions used to control the direction of the locomotive. For Left Rail positive control (the most common in use) switch the Polarity switch to the “Large Scale” position. For Right Rail positive control, switch the Polarity switch to the “NMRA” position. If your locomotive operates in the reverse direction to other locomotives on your layout, place the Polarity switch in the opposite position.
"Large Scale" means the loco should run in the same direction as an LGB Loco (on analogue at least), whereas "NMRA" standard expects the loco to run the same direction as a small scale loco would . For some reason the NMRA didn't like it that LGB opted to wire their locos the opposite to most other scales and brands.
Whether or not this switch has any effect on DCC depends on at what point it's wired into the motor circuit. Just try it and see!
Whether or not this switch has any effect on DCC depends on at what point it's wired into the motor circuit. Just try it and see!
nico said:
Hi Nico
My K-27 is set to run on LARGE SCALE ,by the way do you use DC or DCC track power . Will you be posting pics soon as i look forward in seeing the loco with the AMS Coaches.
thanks richie all seems well uploaded k27 qsi firmware and tested it all with my quantum programmer,i find the connecters from the loco to the tender hard to disconnect and steve some pictures coming up for you
Nico, I've just had a look at the K27 circuit diagram. If you would like a copy as a pdf file please PM me your email address as I can only attach it to an email.
The pickups from the wheels go straight to the battery/track power switch, as do a pair of wires which are intended to be connected to a battery IF you intend using battery power. Unsurprisingly this switch needs to be set for track in your case. This switch then feeds the NMRA/Large scale changeover switch and the output of this switch feeds the main circuit board in the tender, into which you plug the decoder.
On analogue swapping the track wires round, which is what the NMRA/Large scale switch effectively does, will change the direction of travel of the loco. I'm 99.9% sure that with DCC it doesn't matter which way round the track wires go and the loco will always go forwards when the DCC controller is set for forward and vice versa. It is however possible to program the chip to set which end is the front of the loco, not always obvious with some diesel and electrics, but once done it will hold as programmed regardless of track connections.
I also suspect that even LGB/Massoth chips are NMRA compliant to a fair degree which may cause a little confusion with which direction is forward when running an analogue loco on a DCC system.
In short, unless I'm mistaken about the lack of importance of the track feed wires on DCC systems, it doesn't matter which way the NMRA/Large scale switch is set.
The pickups from the wheels go straight to the battery/track power switch, as do a pair of wires which are intended to be connected to a battery IF you intend using battery power. Unsurprisingly this switch needs to be set for track in your case. This switch then feeds the NMRA/Large scale changeover switch and the output of this switch feeds the main circuit board in the tender, into which you plug the decoder.
On analogue swapping the track wires round, which is what the NMRA/Large scale switch effectively does, will change the direction of travel of the loco. I'm 99.9% sure that with DCC it doesn't matter which way round the track wires go and the loco will always go forwards when the DCC controller is set for forward and vice versa. It is however possible to program the chip to set which end is the front of the loco, not always obvious with some diesel and electrics, but once done it will hold as programmed regardless of track connections.
I also suspect that even LGB/Massoth chips are NMRA compliant to a fair degree which may cause a little confusion with which direction is forward when running an analogue loco on a DCC system.
In short, unless I'm mistaken about the lack of importance of the track feed wires on DCC systems, it doesn't matter which way the NMRA/Large scale switch is set.
nico said:
Good to hear alls well
I use a train engineer on DC so i got a Quantum Advanced Analogue Contoller that then gives me all the sounds that you have on DCC . I hate the wires between loco and tender :wits:thats why i built this box to keep them together :bigsmile
Neil Robinson said:
That's correct Neil. On DCC it does not matter which rail is connected to which terminal of the central station, the direction will always be the same even if you reverse connections. You need to set CV29 bit 0 to 1 to reverse the default direction.
However LGB are not NMRA compliant with regard to analog. A LGB locomotive will go backwards when connected to a right rail positive, whether it has a decoder or not. That's the LGB standard, the opposite of NMRA. I've just checked with two LGB locos, one analog the other LGB factory chipped.
And if you need to convert a pdf to a jpg or other graphic format any current Macintosh computer can do that (open with Preview app, then save as required format). Let me know if I can help with that.
don9GLC2 said:
Thanks for the confirmation Don.
With regard to the above I was thinking about the running of a non-chipped LGB loco on an LGB or Massoth DCC layout. I have a nagging suspicion that the analogue loco may travel in the opposite direction to the expected as the LGB or Massoth DCC systems are, to some extent at least, NMRA compatable.
Having looked at pictures of the Dummy Board there completely different to what i have, i am wondering could this be some kind of decoder heres pictures what do you think
nico said:Having looked at pictures of the Dummy Board there completely different to what i have, i am wondering could this be some kind of decoder heres pictures what do you think
It's not the same as the dummy board i have Nico could be some sort of decoder.
It maybe a PLUG-N-PLAY chip that fits a K-27 remember seeing it in a article in GARDEN RAILWAYS about a year back , Would Jeremy have any idea .Richie said:nico said:Having looked at pictures of the Dummy Board there completely different to what i have, i am wondering could this be some kind of decoder heres pictures what do you think
It's not the same as the dummy board i have Nico could be some sort of decoder.
Nico, the circuit diagram I sent you is dated 10th October 2007 and shows a dc PCB (dummy board) with four diodes, two chokes and a capacitor. The photo you posted appears to be a dc board with eight diodes, two chokes and two capacitors and the board states revision A, 17th July 2009. I therefore suspect you just have a more modern version of the dc dummy board shown in the pictures you have seen and than that with which most members are familiar. The revision seems to have increased the level of interference suppression and smoothing and in your case is replaced by the QSI decoder in the same way as the older type.