Recently, when wiring up a loco with a decoder, I checked my direction in analogue was correct, however, when testing in DCC the direction was opposite. I used the inverse direction function of the decoder to correct, but would rather correct the problem with motor leads during installation. Track leads correct polarity in analogue, but how does one correct direction in DCC? I would prefer that decoder 'FWD' is actually forward direction, not using inverse direction to control.
One more digital question - motor polarity?
- Thread starter Tim Brien
- Start date
If you only swap the motor leads, it's likely that the motor will then run the "wrong" way under DC.
I normally find you need to swap all four leads over, to maintain correct polarity from rail to motor for DC whilst reversing the polarity that the motor is fed under DCC control.
Using the "reverse direction" CV setting sometimes means you end up with the directional lighting opposite to the direction of travel (seems to depend on the decoder).
I normally find you need to swap all four leads over, to maintain correct polarity from rail to motor for DC whilst reversing the polarity that the motor is fed under DCC control.
Using the "reverse direction" CV setting sometimes means you end up with the directional lighting opposite to the direction of travel (seems to depend on the decoder).
ntpntpntp said:
Revercing the track pickups will have no effect, you are picking up AC so swooping the wires around makes not a tad of difference. You need to get the DC motor output correct for what you are going to do and indeed swoping the wires round will reverse direction as has been mentioned here. Suggest in all cases that you do a quick test (to get Forward and Reverce correct) with the chip in situ before connecting any lighting wires then you cannot go wrong.
Further more if you think that what I have been saying is wrong, just put your loco on a DC track, if the loco goes left when you turn the controller to left, bodily turn the loco around and it will still go left when you turn the controller to the left.
JonD
Reversing the track pickups will have an effect under analogue DC, which was my point. A decoder with "analogue conversion" switched on simply passes the track polarity through to the motor when there is no DCC control signal. Reversing the motor feeds will have an effect under both DC and DCC.
Therefore, first objective when chipping a loco is to get the motor running in the "correct" direction under analogue DC so that the loco continues to run in the same direction as it did before it was chipped.
If you find the motor runs in the correct direction under DC but wrong direction under DCC, swapping all four wires over at the decoder (not just the motor feeds) maintains the correct relationship of track pickup to motor feed for analogue DC use, AND reverses the motor feed polarity relative to the decoder's "forward" and "reverse" output under DCC control.
Swapping both the motor and track wiring around avoids having to change the CV29 "reverse direction" bit setting. I've found that some decoders don't take notice of this direction setting when running on analogue DC, and some decoders don't apply the same direction change to the directional lighting. You're then into reconfiguring lighting function mapping or swapping the headlight wiring to sort that out.
Therefore, first objective when chipping a loco is to get the motor running in the "correct" direction under analogue DC so that the loco continues to run in the same direction as it did before it was chipped.
If you find the motor runs in the correct direction under DC but wrong direction under DCC, swapping all four wires over at the decoder (not just the motor feeds) maintains the correct relationship of track pickup to motor feed for analogue DC use, AND reverses the motor feed polarity relative to the decoder's "forward" and "reverse" output under DCC control.
Swapping both the motor and track wiring around avoids having to change the CV29 "reverse direction" bit setting. I've found that some decoders don't take notice of this direction setting when running on analogue DC, and some decoders don't apply the same direction change to the directional lighting. You're then into reconfiguring lighting function mapping or swapping the headlight wiring to sort that out.