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DCC sound loco stubborn in DC

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  • Member since
    September 2023
  • 4 posts
DCC sound loco stubborn in DC
Posted by Rob764 on Saturday, September 16, 2023 5:26 AM

Fitsr, I apologize as this is in some way a duplicate question to my first post in this forum. 
I have recently acquired an ATHEARN GENESIS DCC SOUND HO SD70ACe locomotive from an auction. I am impressed by the detail and beauty of this model.

I still don't have a DCC controller so I decided to test it in DC. The manual says the Tsunami Sountraxx decoder is able to tell DC or DCC automatically.
The relevant levels described in the manual are:
5V -> the sound starts
7.5V -> the loco starts moving

Well I actually measured with a meter, the sounds kick in at 7-8V and the motion at 11-12V....
It seems normal that the decoder is eating up something but here I have 3-4 volts difference. Is this normal or should I ask for a return?

(The seller says he tested it succesfully in DCC with a Roco Multimaus)

Thanks

 
  • Member since
    February 2002
  • From: Mpls/St.Paul
  • 13,892 posts
Posted by wjstix on Tuesday, September 19, 2023 10:26 AM

What you describe is very normal. Sound eats up a lot of power, so when running a DCC-sound engine on DC, you have to turn the power way up to get the engine to move. A regular (non-sound) DCC decoder doesn't do that, it will work pretty much the same on DC or DCC.

If you don't plan on ever doing DCC, you could remove the sound decoder. That could be as simple as unplugging the decoder and plugging in a jumper so it runs on DC. Depends on how the engine's decoder is installed.

You might then try selling the sound decoder on Ebay or some other way. Sound usually adds around $75-100 to the price of an engine, so you could get a decent amount for the decoder (and speaker). Or I guess you could just sell the engine altogether, and use the money to buy a non-sound version - and have some money left over.

However, since you have a very nice engine with one of the 'top of the line' sound decoders, you could maybe invest in a DCC starter system (like a Digitrax Zephyr) and get all the benefits of your engine. Short-term, you could add a DPDT toggle switch (I'd use a center-off one) so you can run your layout as a DC layout or as a DCC layout. Long-term it wouldn't be that hard to convert your other engines to DCC.

Stix
  • Member since
    May 2020
  • 1,057 posts
Posted by wrench567 on Tuesday, September 19, 2023 11:29 AM

  Voltage specifications are misleading and really should be removed from their advertising. It's the current that is important. Not knowing what DC power system you have. It could be that at five volts you're not getting the full one amp of current needed to overcome the decoders needs. Also some DC systems will put a pulsed DC current out that is confusing to decoders. I have an old MRC system that puts out pulses of current to help motors start moving. This would confuse the heck out of early decoders to jump start and never really get slow operating control.

    Hope my explanation is clear.

      Pete.

  • Member since
    September 2023
  • 4 posts
Posted by Rob764 on Tuesday, September 19, 2023 1:33 PM

wrench567

   Hope my explanation is clear.

      Pete.

 

It is indeed, thanks

 
  • Member since
    February 2002
  • From: Mpls/St.Paul
  • 13,892 posts
Posted by wjstix on Thursday, September 28, 2023 11:32 AM

Rob764
The relevant levels described in the manual are: 5V -> the sound starts 7.5V -> the loco starts moving Well I actually measured with a meter, the sounds kick in at 7-8V and the motion at 11-12V....

According to the Tsunami manual, setting CV 218 (Analog Mode Motor Start Voltage) and CV 219 (Analog Mode Motor Start Voltage) both to zero will result in the engine sounds starting at 5 volts, and the engine should start to move at 6 volts. Maybe your engine's decoder is set at higher amounts, which would delay motor sounds and movement?

See pg 101 for more:

https://soundtraxx.com/content/Reference/Manuals/Tsunami2/tsu2_diesel_technical_ref.pdf

Also, if you haven't already done so, a good 'break in run' (like 15-20 min forward, and then reverse, at full speed) can sometimes reduce the power draw needed. 

Stix
  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 18,255 posts
Posted by SeeYou190 on Thursday, September 28, 2023 12:06 PM

Rob764
Is this normal or should I ask for a return?

Everything you describe sounds normal to me.

Are you planning to switch to DCC? From your post, it sounds like you are.

That should fix all your concerns.

Sorry for replying in a DCC thread. I know I am out of my element, but I do have experience with dual mode decoders on DC.

-Kevin

Living the dream.

  • Member since
    January 2022
  • From: Michigan, USA
  • 120 posts
Posted by allegedlynerdy on Thursday, September 28, 2023 3:35 PM

To echo everything else said here, the main thing is that DCC has a constant track power available for the locomotive to draw from to do work, when a DCC system tells a locomotive to move at 25% speed, the track still has 100% power, the decoder only draws the amount needed for that 25% speed. DC packs, depending, control it directly with the amount of power - so 25% speed is 25% power to the tracks. This is what causes slow speed DC operation to be difficult - especially on DCC locos, but also on DC - which is why pulsed power is used, which actually goes well above 25%, but in short pulses so the average speed is 25%

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