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reversing wye in DCC

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  • Member since
    February, 2011
  • 9 posts
reversing wye in DCC
Posted by quick-draw on Thursday, March 03, 2011 10:05 PM

Hello all! I'm new to this forum business so I trust you will be gentle with me! I need someone's help with this, please. 

I am building an HO railroad and have a wiring issue with my reversing wye. 

My system is an MRC Prodigy Express and I am using an MRC Auto Reverse Module in the wye. I installed the module according to the instructions; that is one section of the wye was insulated so no power comes into it from either end. I placed the Auto Reverse Module at one end of it with the red wires on the powered side and the yellow wires on the insulated side. My understanding of this is that when a locomotive enters the insulated section, the module reverses the polarity so that the locomotive keeps running as it should and there is a) no short and b) normal operation. Here's what happens; when the locomotive crosses onto the insulated section, the display on my controller switches from what it was displaying (direction, speed steps, etc) to "SVDA" and I lose control of the locomotive! It keeps going of course, but the only way I can stop it is to shut off the power. It happens when the locomotive crosses where the module is. At the other end of the insulated section, it crosses the gap and continues normally and under control. It only happens when the loco crosses the wired gap. 

The guys at my dealership (Trains & Such, in Calgary, Alberta) never heard of this happening and have no idea what it could be. They don't know what SVDA means either!They, in fact, suggested I go on line here and ask you guys! There was no mention of anything like this in the instructions that came with the module nor any mention in the manual that came with my Prodigy Express. The DCC "Expert" at the store said he thought that maybe I should put another module at the other end! I can't see this working but what do I know? Maybe he's right! I hope you guys can help!! Thanks so much in advance.

  • Member since
    October, 2010
  • From: Vancouver, WA (SP&S country)
  • 90 posts
Posted by Capt. Brigg on Thursday, March 03, 2011 11:24 PM

If I understand your description, you have insulated only one of the two rails of the reversing wye.  It is my understanding you need to insulate both rails so that no power or signal crosses over into the reversing block. I'm not familiar with the MRC auto reverse module, but I think that is how the rest of the hobby operates.

Capt. Brigg Franklin
USCG Licensed Marine Officer
Certified crazy train chaser
www.pacificcascaderailway.com

  • Member since
    September, 2004
  • From: Dearborn Station
  • 11,843 posts
Posted by richhotrain on Friday, March 04, 2011 5:08 AM

Apparently, SvDa stands for SaveData according to MRC.

Click on the link below.  Once you are on the MRC web site, click on the words "CLICK HERE for the Prodigy tips and tricks" which will open a PDF document.  There are five references to SvDa in the document with explanations on how to deal with the message.

http://www.modelrectifier.com/train-controls/dcc-prodigy.asp

If you Google "MRC SVDA", there are a number of references to this message including a previous thread posted on this forum.

http://cs.trains.com/trccs/forums/p/110552/1276803.aspx

Rich

  • Member since
    March, 2007
  • From: South Carolina
  • 1,623 posts
Posted by Train Modeler on Friday, March 04, 2011 5:37 AM

Calling MRC directly on a problem with their product is probably the easiest path.   They're pretty good on customer service.   And if you need to return it, you'll know right away.

I prefer PSX-AR for reversing section.

Richard

  • Member since
    February, 2011
  • 9 posts
Posted by quick-draw on Friday, March 04, 2011 10:27 PM

Hi Capt! Thanks for your reply! I actually DO have both rails insulated so that's not it however, another poster did respond and gave me a link to the MRC site where they discuss this issue! sVdA means"SAVE DATA."  Turns out my Prodigy Express is small; only 1.6amps and due to this is very sensitive to shorts etc. I have 2 options;

1) disconnect the control for a couple of seconds and the reconnect it. This bumps it over the initial short that gets the reverse module to switch polarity and I regain control of the locomotive.

2) send the system back to MRC for a software upgrade and a boost in the power (2.5amps). They just charge for shipping & handling; the upgrade is free. 

I ran downstairs to the train room and IT WORKS!!! YAYYY!!!!! I might do the upgrade later but for now at lewast the %$##%^ thigs works!!

 

Again, thanks for responding; I got you and 3 others answering me in just a few hours! Great community

  • Member since
    February, 2011
  • 9 posts
Posted by quick-draw on Friday, March 04, 2011 10:31 PM

Thank you Train Modeller for the input; that was my next step! Turns out richhhottrain gave me a link to a help page on the MRC site that deals with my problem and it works! 

Thank you very much nonetheless for the help; it's appreciated and I will remember!

  • Member since
    February, 2011
  • 9 posts
Posted by quick-draw on Friday, March 04, 2011 10:42 PM

You hit the nail on the head richhottrain! Thank you very very much, brother! It took me less than 2 minutes to find the mention of my specific problem. My system is a small starter type with only 1.6 amps. As such, it is very sensitive to shorts and it is an actual short  that operates the reverse module so that's what causes the loss of control. Option 1; unplug the the controller for a couple seconds and plug it back in. This resets the controller and I get control of the locomotive back. This relieves the problem. I ran right down to the train room and it works!!!! YAYYY & thank you so much! Option 2; send the DCC system back to MRC and they will give it a software upgrade plus a power boost to 2.5 amps. They will do this for just the cost of shipping & handling. I might do that, but am simply pleased to have it properly diagnosed and am now able to run locos through the wye!!!!!

  • Member since
    September, 2004
  • From: Dearborn Station
  • 11,843 posts
Posted by richhotrain on Saturday, March 05, 2011 7:33 AM

quick-draw

You hit the nail on the head richhottrain! Thank you very very much, brother! It took me less than 2 minutes to find the mention of my specific problem. My system is a small starter type with only 1.6 amps. As such, it is very sensitive to shorts and it is an actual short  that operates the reverse module so that's what causes the loss of control.

Q-D,

Glad that I could be of some help to you.

That's what you and I, and a lot of others, love about these forums.  The ability to get quick help with our problems, and fixing those problems, is what it is all about.

Rich

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