N Scale 2-8-4 won't run on DC

VPJohn · December 05, 2015, 01:34:46 PM

I can run both DC and DCC on my N scale layout. My 2-8-4 runs fine on DCC, but I only get sound when I turn the DC voltage up to about 5.75. As I turn the DC voltage up to 10 or 12 - the sound continues but the engine does not move. Is there a CV I need to check/change? Any other ideas?

Mike C · December 05, 2015, 04:56:26 PM

Have you tried a decoder reset ? Setting CV 8 to 8 resets the decoder to factory original . It will run on address 3 after the reset .

Hunt · December 05, 2015, 05:19:01 PM

VPJohn,
What DCC system do you use? To what address did you program the locomotive?

What DC power pack are you using?

brokemoto · December 05, 2015, 07:36:53 PM

Some locomotives equipped with a so-called "smart" decoder do have problems running on pulsed DC. I do not use DCC. I do have some
B-mann power that has this so-called "smart" decoder. They run fine if I use the MRC 2400, with the pulse switch ON or OFF. They run fine on the MRC 2800. They run fine on the MRC 1300. They run in mediocre fashion on the various "train set" power packs (that is the fault of the power supplies rather than the locomotive or decoder). Most of them will run fine on the MRC 2500, but there are some that have problems. Some will change direction suddenly without my throwing the direction switch. Some will change speed without my touching the throttle. Some will run in the direction opposite to what I have set the direction switch. Some refuse to move at all.

The MRC 2500 has a pulse that is stronger than the other TECH II power supplies.

B-mann used to sell a SPECTRUM DC power supply, but I do not think that it is in current production. I have no experience with it, except that one of the hobby stores that I used to frequent (it has since closed) had it as power for the test track. It seemed to be allright.

So, I , too , would wonder what DC power supply you are using.

Hunt · December 05, 2015, 07:58:20 PM

Quote from: brokemoto on December 05, 2015, 07:36:53 PM
Some locomotives equipped with a so-called "smart" decoder . . .

It is referred to as a dual-mode decoder.

gatrhumpy · December 06, 2015, 08:53:22 AM

On dual mode sound decoders the voltage has to be turned up to about 5V before you get sound.

VPJohn · December 06, 2015, 10:27:01 AM

Thanks for the good replys. I reset CV8 to 8 and now the 2-8-4 will run on DC. It is interesting to compare how the loco runs on DC with how it runs on DCC. DCC is much smoother. I have an MRC 1500 power pack and always keep Momentum turned off.

plas man · December 06, 2015, 10:59:40 AM

of note Bachmann UK informs me that ..
The dual mode decoder will work on DC and DCC . However the dual mode decoder will not work Analogue (No 10 or 0) on the DCC controller . Doing so could damage the decoder/loco motor .

gatrhumpy · December 06, 2015, 03:03:28 PM

Quote from: VPJohn on December 06, 2015, 10:27:01 AM
Thanks for the good replys. I reset CV8 to 8 and now the 2-8-4 will run on DC. It is interesting to compare how the loco runs on DC with how it runs on DCC. DCC is much smoother. I have an MRC 1500 power pack and always keep Momentum turned off.

This is common with dual mode decoders.

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N Scale 2-8-4 won't run on DC