BMMECNYC RR_Mel The one that stands out is the T4X, can I use a T4X and a T1 in a tandem A B configuration and will both decoders BEMF auto sync? That may be a question for the TCS themselves. Also those decoders are not sound decoders. Incidentally, TCS has this: "All decoders are covered by a one year, goof proof, no questions asked warranty. Decoders outside of the warranty which cannot be repaired can be upgraded for a nominal replacement fee." How old are the SD40-2s?
RR_Mel The one that stands out is the T4X, can I use a T4X and a T1 in a tandem A B configuration and will both decoders BEMF auto sync?
That may be a question for the TCS themselves. Also those decoders are not sound decoders. Incidentally, TCS has this: "All decoders are covered by a one year, goof proof, no questions asked warranty. Decoders outside of the warranty which cannot be repaired can be upgraded for a nominal replacement fee."
How old are the SD40-2s?
RR_MelThe one that stands out is the T4X, can I use a T4X and a T1 in a tandem A B configuration and will both decoders BEMF auto sync?
rrinker Your DC power pack, if it's a fairly fancy one, may be doing voltage compensation going up the grades to keep things moving. What happens if you increase the throttle on the DCC when going up hill (being like the prototype, unless motor power is increased, a loaded loco will slow down doing up hills)? The DH123 decoders do not have BEMF so they cannot compensate for speed variations on their own, however there are tuneable motor parameters that may need to be adjusted based on the type of motor in the loco. The DH165 series do have BEMF, but the default settings may not be approriate for the specific motors. Try a TCS decoder - they have auto adjusting BEMF. It will run a bit erratically when first installed, but as the loco runs for a while, it smooths out as it finds the best settings for the motor. After that, super smooth. And no CVs to set to get it to work well, just set the address. --Randy
Your DC power pack, if it's a fairly fancy one, may be doing voltage compensation going up the grades to keep things moving. What happens if you increase the throttle on the DCC when going up hill (being like the prototype, unless motor power is increased, a loaded loco will slow down doing up hills)? The DH123 decoders do not have BEMF so they cannot compensate for speed variations on their own, however there are tuneable motor parameters that may need to be adjusted based on the type of motor in the loco. The DH165 series do have BEMF, but the default settings may not be approriate for the specific motors.
Try a TCS decoder - they have auto adjusting BEMF. It will run a bit erratically when first installed, but as the loco runs for a while, it smooths out as it finds the best settings for the motor. After that, super smooth. And no CVs to set to get it to work well, just set the address.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Yes, try changing CVs 2, 5 and 6 to zero (and maybe 3 and 4, which control momentum). That should make the engine run the same as it does under DC - unless you have (intentionally or not) set it up to use a speed curve. If CV 5 is set at say 125, you've basically cut the maximum power going to the engine by about 1/2.
Most decoders have separate CVs (Configuration Variables) for DC-operation max voltage and DCC-operation max voltage. Check their values to see if your decoder is limiting how much voltage goes to the motor under DCC.
Also, get a scale speedometer (or the old method, a yardstick, stopwatch, and calculator) to find out how fast your engine goes under DCC. It might be that the decoder limits the engine to prototypical speeds, which is not the case when there's no decoder installed.
--Steven Otte, Model Railroader senior associate editorsotte@kalmbach.com