Converting a brass engine to DCC

[Hergy]

Check the latest MRR (Jan 2011). Good article on adding 2 decoders to a brass steam loco.. This may also answer some of your other questions.

[AustraliaJim]

I converted my first brass loco using info from this web site. Very Very helpful. Have a good look around the site and you'll find it all.

http://www.markschutzer.com/

Cheers

 

Jim

[rrinker]

 It really is just the brushes, however a common shortcut in motor design was to mount one brush on a small piece of insualting material, and the other right to the motor case. Bowser motors were like this too - for a while Bowser offered a repalcement that was the same motor but with BOTH brushes mounted to the insulating material, all ready for DCC.

 If the brush is mounted to the motor case and there's no way to change that, then you need to go one level up and isolate the motor. Motor mounting is important - if you remove the motor and put a layer or two of tape under it to insulate it from the frame, then screw it back down - the METAL motor case to the METAL frame with a METAL screw - ooops!

 And it's not just brass, or Athearn - Proto 2000 Alco S-1 switchers come with one motor brush grounded to the frame. It's easy to fix, since the brush holder part of the motor is all plastic, but since these locos have an 8 pin decoder socket you might be fooled into thinkign they are DCC ready and simple convert. They are - until the first time it derails and one of the wheels contacts the frame and fries the decoder.

                               --Randy

 

[Paul3]

Train Modeler,
IMHO, if one wants a realistic test of current requirements (rather than the maximum stall current), run the engine against a bumper with the ammeter on it.  Turn on all the lights, and run the engine at full speed.  Look at the meter.  If it's less than 1 amp, then just about every decoder will be fine.

It's certainly possible that rubber tired and very heavy engines will not spin their wheels under a load, and therefore it's stall (full) current.  This, however, is rare in my experience (and at my club we've registered over 1100 engines).  Even the pulling champion at my club, the BLI N&W Class Y-6b with rubber wheels that maxed out our scale at 16oz. of pulling power, slipped the wheels.

Using stall current is absolutely the safest route to go for judging whether a DCC decoder can handle it.  But it's generally not necessary for the vast majority of applications.

Oh, and double motors always should get double decoders, IMHO.

hwolf,
It's just semantics.  The idea is expressed simply by saying the "motor must be isolated from the frame" (probably a hold over from the Athearn BB locos where one must pull the motor out and isolate it).  In reality, the motor housing isn't important.  It's the motor brushes that is important.  So really, people should say, "The motor brushes must be isolated from the frame."  If the motor housing is part of the circuit, then life gets more interesting and you have to put down tape and use nylon screws (see Atlas S-units for an example of that).

Oh, and I do agree with everything Fred says. 

Paul A. Cutler III

 

[trainnut1250]

From my limited experience installing sound decoders in brass steam locos: 

1. Mount the decoder and speaker in the tender if you can.  Much easier for the first install.

2.  Check the electrical pick up reliability on your loco.  Try creeping it at low speed in DC.  If it stalls, consider adding more pick-ups to the drivers or tender trucks (depending on the loco).  Sound decoders like a steady, un-interrupted current supply.  Bare minimum - solder a wire from the tender trucks to the floor of the tender.

3.  Are there pre-drilled holes in the tender floor??  If not, you will want to be extra careful when drilling to not bend, distort or warp the floor when applying pressure with a drill or drill press, (recommended).  You will probably have to drill holes for the wires even if the tender is pre-drilled.  Slow and steady is the key.

4.  IS this loco painted?  Does it have headlights installed?  Operating front couplers?  You might want to complete these tasks before decoderizing.  Caveat: I have several unpainted brass locos with sound decoders in them that will have to taken apart later when they are painted….I figure this will be years from now so I am willing to redo some of the work when it comes time to paint, so that I can run ‘em now.

5.  Use the micro TSU if the motor amp draw is low enough.  This leaves room for the biggest speaker that you can find and a capacitor.  Even large locos never seem to have enough room in the tender.

6. Skip the wire plugs and hardwire the engine and tender together.  I have found the plugs are clunky, take lots of time on the install and I am not taking the locos anywhere, so the locos never go in boxes.  A recent count of hose connections between loco and tender on a small real, live Sierra 2-8-0 was over 10, so lots of wires painted as hoses aren’t un-prototypical.

7. Get some ultra fine wire from Minatronics etc to make your connections between tender and engine.

8.  Consider the high bass speakers.  They do sound real good.

9.  Use the stay alive capacitor.  Consider upping the stay alive capacitor to the largest size the you can fit in the loco.  I’m shooting for 5K mfd.  Haven’t been able to find any small enough.  I have used some big caps (1.5k plus) in some tests with the Tsunami and it does smooth out performance and eliminates momentary power glitches.  Use a diode/resistor to slow down power in rush on DCC system short reset/start-up.

10.  Find some one local who has lots of brass experience.  There are lots of tricks and gotchas.  I know a couple of experts and they have rescued me a couple of times.  Very handy…

11. Google Mark Schutzer.  He has a lot of info on DCC installs in brass

I hope these tips help.  Good luck with the installs.  I have not regretted taking the time to put decoders in my brass locos.

 

Your Mileage may vary,

 

Guy

[hwolf]

My soldering skills are good.  The idea was not a money issue, but an idea that I could increse my Model Railroading fun.  Thanks all for your help.  If I go ahead with it I am sure I will be back with more questions.

[modelmaker51]

The decoder will come with instalation/wiring instructions, but what has been described with red/b/ack/orange/grey wires was correct.

Use shrink tubing (Radio Shack) to insulate any splices.

Make sure the loco runs well on DC, if it doesn't it's going to run worse on DCC.

If you do decide to go with sound, you will definitely have to add more electrical pick ups, I would recommend they be added anyway, even without sound for reliabillity.

If you've never had any experience wiring locomotives, (how are your soldering skills?), you could save yourself a lot of heartache by paying someone to do the installation. Richmond Controls and others do it for very reasonable fees (usually $25-$35).

[fwright]

hwolf

Paul

I like your comments.  I am not going to use sound or lights at this time.  One question.  Everyone has said that the MOTOR has to be isolated.  Why is there such a difference of opinon?

Paul is correct if one motor brush is not grounded to the frame.  All can motors and some open frame motors come with the brushes insulated from the motor frame.  However, some open frame motors have the brush grounded to the motor frame (only one brush has a wire attached to it), and the motor frame is usually grounded to the locomotive frame through metal fastenings and/or the shafts and gears.  I have seen the latter arrangement in many older model locomotives, including one of the two low-end brass models I own.

To check, detach the motor wire(s) and measure the resistance from each brush terminal to the motor frame.  You should get infinite, and life is good.  You only have to insulate the brushes from the locomotive frame.

If you get a small resistance from either brush to motor frame, then the entire motor must be insulated from the locomotive frame.

Your original post said you wanted both a DCC and sound installation.  A sound installation is more complex due to the need to locate and install a speaker and enclosure as well as the decoder.  My comments were made with installing a DCC sound decoder and speaker in mind.

The final wiring setup depends on what you do or do not do to enhance electrical pickup.  As it stands, your stock PFM (assumes built in the '60s, design changes may have been made in later production) comes with the tender picking up from one rail, and the engine picking up from the other rail.  The wire from the tender to the engine brings the power from the tender to one brush of the motor.  The drawbar is insulated.

Fred W

[Vail and Southwestern RR]

The motor contacts have to be isolated from the rails.  The bottom line is that the input to the decoder (the rails) has to be isolated from the output of the decoder (the motor).  You are going to want to meter to prove that this is true before you power up.  There are some exceptions for the function outputs, but for now there's no need to worry about that.

Basic wiring, the right rail goes to the red wire, the left to the black.  The side of the motor that used to go to the right rail goes to the orange, the side that used to go to the left goes to the gray.  Depending on the loco, you'll still get it wrong, and it will run the "wrong" way.  Swap the orange and gray, and away you go.

[hwolf]

Paul

I like your comments.  I am not going to use sound or lights at this time.  One question.  Everyone has said that the MOTOR has to be isolated.  Why is there such a difference of opinon?

Where do I find the basic wiring instructions?

I would also like you and Fred above to comment on your posts.  Do you basicly agree with each other?

[Train Modeler]

I have had issues with stall current blowing up decoders, so in my opinion be concerned.   Particularly if the loco is relatively heavy and/or has rubber tires.        I've also added Soundtraxx to a Bachmann DD40AX and blew out a decoder due to them having two motors.      So, it's not just the stall current, but overall current, including lighting, etc. 

[Paul3]

Putting DCC (only) in a brass steam engine is usually pretty easy.  It takes me about an hour from start to finish without any lights.  It's much easier than, say, installing a DCC decoder in an Athearn Blue Box loco.

It is not important that the motor be isolated from the frame, no matter what anyone tells you.  It's critical, however, that both motor brushes be isolated from the frame.  Every brass engine I've ever seen has the brushes isolated from the frame.  I'm sure there are some out there that are not isolated, but to date I've never seen one.  Look at the motor installation.  If there are two wires to the motor, then all you have to do is cut them.

I remember a member of my club who thought he needed to isolate the motor from the frame.  He fabricated a plastic mount and used epoxy and nylon screws to hold it down.  Yet, when I looked, all he had to do was cut the wires to the motor.  Oh, well. 

Putting in extras like lights can get interesting.  I highly recommend Minatronics small plugs for carrying power between the tender and loco.  If you can get the decoder in the boiler and don't use a rear backup light, then you can just use the drawbar and no plugs.  But if you put the decoder in the tender and you want a headlight, then you need 5 wires between tender and boiler.

Oh, and I don't worry too much about stall current.  As long as the wheels slip under a load and the slip current is under the load limit of the DCC decoder, then you'll be fine 99% of the time.  Think about it: how often have you ever had a situation when then loco has full power but the wheels won't move?  In my experience, never.  Sure, if you have a catastrophic failure in your drive line and it jams up, then it might blow the decoder, but that just doesn't happen too often.

Sound is tricky due to the size of the sound decoder and the speaker.  Some brass tenders are easy to convert due to the holes in the floor for the old PFM sound system.  Others are near impossible due to having a small tender with a full-size coal pocket complete with stoker screw.

Personally, if this is your first brass DCC conversion, I would only do the DCC motion decoder.  Doing a sound install for your first try is like jumping into an Indy Car with your learner's permit...you'll probably break something and get frustrated.

Paul A. Cutler III

[fwright]

hwolf

I have a 40 year old Pacific Fast Freight Brass engine made by United....I would like to convert this engine to DCC with sound. I have no experience working with engines either wiring or insulating etc.

Question: Where can I find step by step information to convert from DC to DCC /Sound?

Any tutorial won't be specific enough to your engine (which you did not identify the model or any changes made since manufacture) to be "step by step".  What will have to be done will be heavily impacted by a series of decisions you have to make regarding the installation.  When you pay somebody to do the installation, you are paying him to make those decisions for you.  I can give you a little of a process guide - tbdanny started down the road in his post.

• Determining present condition of the model.  What is the current draw and condition of the existing motor?  Will the current draw fit within the specs of the intended decoder?  Is the mechanism smooth running, or does it need some tweaking?  Is better electrical pickup needed - DCC sound decoders are particularly finicky about absolutely no momentary interruptions in the power?  Is a flywheel needed or wanted?  Is the model painted and detailed to your satisfaction?  The whole point of this paragraph is determining what needs to be done in preparation for installing DCC.  Remotoring/regearing/adding flywheels/improving electrical pickup to all wheels is not uncommon when installing DCC in an older brass loco.
• What decoder and speaker(s) are you going to use?  Where are you going to locate them?  Will you use a top-fire or bottom-fire speaker arrangement in the tender, or will you put the speaker in the engine?  Have you allowed space for a speaker enclosure - critical for good sound?  What will you use for the wire cables going from engine to tender?  Will you use a plug arrangement, or hard-wire the tender to the engine?  The locations of motor, decoder, speakers, and any lights will determine the wiring needs.  As will the electrical pickup scheme.  This is the planning stage after you have prepared the model for DCC.
• Once the installation has been planned, then is the time to drill and solder and cut and file.  There will be obstacles to overcome here, too.  The speaker enclosure should be airtight to the speaker cone.  Mounting everything electrical/electronic so that it is electrically isolated from the engine and tender frames will challenge you.  As tbdanny stated, both the engine and tender frames and superstructures are normally hot (and of opposite polarities) - and that is not easily changed.  You have to make sure the motor is isolated from the frame - often the mechanism conducts into the motor through the gearing and shafts and causes problems.  This may or may not be a problem depending on the motor design.

Just as steam engines were custom built and/or modified for their actual use, so a DCC and sound installation into an existing older model is going to be a custom installation to fit the specific situation.  None of the steps by themselves is all that difficult, it's just that you are performing significant modifications that are best-served by advance planning and preparation.  DCC and sound installations are often done to make a good brass model better, so it's a doable project.

my thoughts, your choices

Fred W

[hwolf]

I noted down your advise,  but I hope someone can come up with the basics.  As I mentioned this is my first attempt.

[Aikidomaster]

I have a friend who works with Rivershore Models. One man sells brass models and the other one custom paints, weathers, regears, remotors and installs DCC. I have had them place the Tsunami DCC sound system in several of my locomotives. Some of the locomotives I purchased from them, others were ones I had bought years ago and Charlie is doing the work for me. Google Rivershore Models for more information.

[tbdanny]

Hi,

While I can't point you to any tutorials, I can offer the following brass-specific advice:

1) Check the current draw of the motor.  This is usually done by holding the motor shaft so that it can't turn, while measuring the current drawn with a multimeter.  Older brass locos usually have open-frame or older can motors, which can draw enough to blow most of the sound decoders currently on the market.

2) Most, if not all of the model in a brass locomotive is live.  The chassis on the locomotive is used to carry pick-up from one side of the track, and the tender is the other side.  You'll need to bear this in mind with regards to isolating, conductivity, etc.  In particular, you will need to make sure that the motor is completely isolated from the frame.  Some models have screws that serve to both conduct electricity and hold the motor in place - these will need to be replaced with Nylon screws.

Hope this helps,

tbdanny

[hwolf]

I have a 40 year old Pacific Fast Freight Brass engine made by United. When I built my new layout where I had Prodigy I was able to run the engine which of course was DC.  Now I use Prodgy Advance which will only run DCC.

I would like to convert this engine to DCC with sound. I have no experience working with engines either wiring or insulating etc.

Question: Where can I find step by step information to convert from DC to DCC /Sound?

Thanks in advance for your help.