Trains.com

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Convert DCC back to DC?

12593 views
11 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    March 2017
  • 86 posts
Convert DCC back to DC?
Posted by gthomson on Tuesday, May 19, 2020 2:33 PM

I recently purchased a used Spectrum Peter Witt trolley car which was ready to run for DCC & DC. To run it just on DC there was this little "dummy plug" as they called it which snapped into the decoder and removed the DCC plug. 

Would there be a similar option for another engine I have that I believe was converted to DCC? It is a Walthers Trainline EMD F40Ph. I believe it was meant to be DC (which I thought I was buying at the time) but the person I bought it from had converted it.

A long winded way of saying I would like to run it on DC without ruining it.

  • Member since
    September 2014
  • From: 10,430’ (3,179 m)
  • 2,311 posts
Posted by jjdamnit on Tuesday, May 19, 2020 3:52 PM

Hello All,

Have you removed the shell to see what you are dealing with?

Was the suspected DCC conversion hardwired (soldered), plug-n-play with an 8-pin decoder or an Original Equipment Manufacturer Printed Circuit Board?

Until you know what you are dealing with it's difficult to advise you.

Dummy plugs for an 8-pin shouldn't be that hard to find. I've got several just sitting in my parts tray. 

If the decoder is hardwired or an OEM PCB the task will be more involved.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

  • Member since
    March 2017
  • 86 posts
Posted by gthomson on Wednesday, May 20, 2020 10:32 AM

Thanks, will take a look. A bit tight trying to get the shell off so need to move cautiously. 

  • Member since
    February 2002
  • From: Mpls/St.Paul
  • 13,892 posts
Posted by wjstix on Wednesday, May 20, 2020 11:21 AM

Some very early "DCC equipped" Atlas engines had a six-pin plug that you had to move to change it from DC to activate the installed DCC decoder. But I don't recall any other manufacturer doing that.

Engines that are not DDC-equipped from the factory often have a green light board with an eight-pin receptacle with a dummy plug in it. You remove the dummy plug to plug in a decoder. To change it back to DC-only, you would do the reverse.

Keep in mind virtually all decoders are "dual mode", meaning you can run the engine on DC or DCC. Before doing anything else, try running the engine on DC and see what happens. It's not going to hurt the decoder.

Note that there is a setting on the decoder that can essentially 'turn off' dual mode, so they only respond to DCC. Some DCC decoders seem to work better when they're set to DCC only. If the decoder is set that way, it won't do anything when you try it on DC - but again, it doesn't harm the decoder.

Stix
  • Member since
    October 2006
  • From: Western, MA
  • 8,571 posts
Posted by richg1998 on Wednesday, May 20, 2020 2:55 PM

If the loco is hard wired and the decoder is dual mode, it will not start the loco until the track voltage is about seven volts. The decoder will wake up at about five volts. The computer chip on the decoder runs at five volts.

Nature of the beast. If the DC option CV has been disabled by the previous user, it will not respond.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Thursday, May 21, 2020 8:37 AM

That's only if it's a sound decoder. A motor only decoder, so long as CV29 is configured to allow DC operation, doesn't work like that. There's maybe less than 2 volts needed to get power to the motor, same as a plain DC loco with constant lighting installed.

 The sound decoders need a lot more voltage because they do need the computer ship to run, and the amplifier to have power, so you cna have sounds without the loco tearing down the track at warp speed. So the first 6 volts or so goes to just powering the electronics.

                                  --Randy

 

                                             --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Thursday, May 21, 2020 9:30 AM

BTW, this is almost certainly a ahrd wire install.

https://tcsdcc.com/installation/ho-scale/1508

Those Trainline locos (I have an FA) just had those simple circuit boards, no 8 pin or 9 pin plugs.

                                   --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    July 2006
  • 93 posts
Posted by fisker4jc on Sunday, June 5, 2022 3:30 PM

I was wondering what it would take to convert a proto 2000 engine from DCC back to DC.  it is just the matter of unpluggint the decoder?  Woulkd I need a dunny 8 pin plug, or is it more complicated?

  • Member since
    October 2005
  • 1,047 posts
Posted by betamax on Monday, June 6, 2022 5:47 AM

fisker4jc

I was wondering what it would take to convert a proto 2000 engine from DCC back to DC.  it is just the matter of unpluggint the decoder?  Woulkd I need a dunny 8 pin plug, or is it more complicated?

 

Some didn't have a plug, and you had to cut traces on the circuit board as part of the conversion, assuming it was left in place. With a larger decoder it may have been completely replaced by the decoder.

If the decoder is hard wired, just disconnect/remove it and wire the pickups directly to the motor.

  • Member since
    February 2003
  • From: Morristown, NJ
  • 808 posts
Posted by nealknows on Monday, June 6, 2022 6:50 AM

If the decoder came pre-installed from the factory, they should work (as many do) on both DC and DCC. Why go thru work and effort to remove it if it already runs on DC? Even if you bought it used, and it runs on DC, just leave it alone..

 

  • Member since
    February 2002
  • From: Mpls/St.Paul
  • 13,892 posts
Posted by wjstix on Monday, June 6, 2022 8:42 AM

fisker4jc

I was wondering what it would take to convert a proto 2000 engine from DCC back to DC.  it is just the matter of unpluggint the decoder?  Woulkd I need a dunny 8 pin plug, or is it more complicated?

 
First, try running it on DC. As has been noted, it should work on DC with no problems. Almost all after-market DCC decoders are "dual mode" meaning they work on DC or DCC just fine unless the previous owner adjusted the CV to not allow DC operation.
 
If you really want to remove the DCC decoder, you'll need to either plug in the dummy plug (assuming it came from the factory with an eight-pin receptacle) or, if it's a "hardwire" installation, you'll need to get out your soldering iron and remove the 9-pin harness and wiring, and re-wire the engine for DC.
Stix
  • Member since
    February 2008
  • 8,877 posts
Posted by maxman on Monday, June 6, 2022 11:38 AM

Need to know exactly which loco it is.  On some one needed to cut a trace on the original light board if a decoder was to be installed.

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

There are no community member online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!