# Old DC steamer to DCC



## danpuckett (Dec 31, 2014)

I have an older unit (DC) that I would like to convert to DCC. It looks like the power comes to the motor off the drive wheels. There is a wire coming off the motor that connects to the tender to complete the circuit through the tender wheels. I do not see any wires coming off the drive wheels to the motor. I assume there is some integral connection deep within the unit. I have not completely disassembled the unit yet. Thought I would see if anybody has worked on a unit this old. The steamer is a 0-4-0 Pennsylvania. It runs good on DC; just wanting to upgrade.


----------



## Mark R. (Jan 26, 2013)

Chances are pretty good the engine's chassis provides the ground from the driver wheels to the motor. 

Your first step would be insulating the grounded motor case from the chassis. Nylon replacement screws and electrical tape will easily accomplish this. Since the driver wheels are also grounded through the chassis, there is no simple way of isolating them from the chassis - aside from flipping the axles and adding external wheel wipers.

A grounded chassis from the wheels may not be ideal, but it would still work as some modern engine models still use the chassis as common ground (Athearn RTR I believe).

With your motor isolated - make double sure it is no longer electrically connected to the chassis - connect the gray wire from the decoder to the one wire on the motor and the orange wire to the motor case (or the opposite brush from the gray if you can). Connect the decoder black wire to the engine chassis and the red wire back through to the tender for the opposite rail pickup.

It can be tricky, but it is do-able.

Mark.


----------



## DonR (Oct 18, 2012)

The motors on older locos often draw excessive
current. You could do a stall test on yours.
Hook up your multimeter set to AMPS (you usually
have to change jacks for one of the probes). Put
the meter between your DC power source and the
track. Hold the loco by hand as you raise the speed
control. Press down slowly until the loco stalls, note
the current. If it gets near 1 amp you should make
certain that the decoder you buy is capable of handling
1.5 amps. Many do today.

Don


----------



## Lemonhawk (Sep 24, 2013)

Look closely at the connection to the brushes. One wire from the tender probably goes to one of the brushes and if you're lucky the other brush is strapped to the chassis or motor frame. It may be possible that you just need to remove that connection to the brush. Its the brush connections that need isolation, if you can isolate the the brush connection from the chassis then you can leave the motor mounted as is. You can test the isolation by using a multimeter on the OHMs setting to see if the brush is isolated from the chassis. Its also possible to replace the motor permanent magnets with newer ones to reduce the current draw.


----------



## danpuckett (Dec 31, 2014)

*amp pull on motor*

The steamer motor pulls .66 amps with wheels spinning at full transformer. At stall the motor pulls 1.77 amps. Is that do much for a digitrax DCC decoder?


----------



## Mark R. (Jan 26, 2013)

Most decoders have a maximum current rating of 1 to 1.5 amps. Your stall current exceeds what would be considered safe.

However, that being said, what are the chances of the wheels binding up at full throttle ? Slim to none I would guess as you probably will never be running the engine at full throttle. 

Personally, I would say you are safe to install a decoder, but keep in the back of your mind, there IS a potential to overload the decoder if the extremes are met.

Mark.


----------



## DonR (Oct 18, 2012)

Dan

Get a decoder rated at 1.5 amps and you'll
do OK. If the loco was pulling only .66 amp
running at full throttle it will use much less
when running at a reasonable layout speed.

Some important things to do for conversion:

Identify the motor tab that is powered by
the right side wheels. The decoder manual
will tell you which color wire to attach to it.

Make certain that neither motor tab is in contact
with wires from either rail. And test the motor
case to see that it is insulated from the tabs.
It may need to be isolated from the frame.

After installation but before putting on track first
time, check again to make certain the motor and
light wires are not shorted to either rail.

Enjoy

Don


----------



## Lemonhawk (Sep 24, 2013)

You could replace the magnets on the motor which will reduce the current draw.


----------



## MtRR75 (Nov 27, 2013)

Consider putting your DCC module in the tender. You do have to run a wiring harness from the loco to the tender, but you have lots more room in the tender. If you go to sound, there's room for a speaker there, too. To let the sound out, drill some holes in the bottom of the tender, or drill a bunch of tiny ones in the coal load -- almost invisible.

Some locos already have pickups in the tender. If yours doesn't, consider adding them during this upgrade. When steamers pick up power only from the drive wheels, there are sometimes problems with the locos losing power when the wheels run over the turnout frogs. To see if you have this potential problem, run your DC loco SLOWLY over each of your turnouts (in all 3 directions), and watch the headlight.

If the headlight blinks, you have a potential problem with power pick-up. DCC is much more sensitive to brief power blinks than is DC. So in this case you might want to add pickups in the tender for redundancy.


----------



## danpuckett (Dec 31, 2014)

Thank you, all of you for the help. I have ordered a Digitrax decoder. I have isolated the motor leads. The pickup for other rail is in the tender. I will let you know after install.


----------



## MtRR75 (Nov 27, 2013)

danpuckett said:


> Thank you, all of you for the help. I have ordered a Digitrax decoder. I have isolated the motor leads. The pickup for other rail is in the tender. I will let you know after install.


I have two locos with that same arrangement -- the right side picks up on the driver wheels; the left side picks up on the tender wheels (both trucks). I am having some problems with one of these locos stalling on the turnouts when the right wheels cross the frog. I am considering splitting the tender pickups so that one truck picks up on each rail. However, It is possible that leaving only one tender truck picking up on the left side will lead to the same problem when that truck crosses the frog.

I'm not planning to do this modification soon. I am still working with the turnouts, since the problem does not occur on all turnouts.

So this is just food for thought for your situation. If you don't have the stalling problem at turnouts, I would leave the pick-up wiring the way it is.


----------



## DonR (Oct 18, 2012)

It seems to me that if you rewire the tender
pickups, do it as all wheel, that is; all right
wheels pick up the right rail, and all left
wheels pickup the left rail. You may have
to add wipers but that's not difficult. You
should have continuous positive power
going through turnouts that way.

Don


----------



## MtRR75 (Nov 27, 2013)

DonR said:


> It seems to me that if you rewire the tender
> pickups, do it as all wheel, that is; all right
> wheels pick up the right rail, and all left
> wheels pickup the left rail. You may have
> ...


Thanks for the suggestion. I had not thought about that option. I might work on that after the holidays -- when I have more time. Two questions.

(1) Where can I find pick-up wheel sets that pick-up from both sides. All of the pick-up wheels that I have collected have a pick-up axle and with one insulated wheel. All of my metal wheels are KaDees. I have heard that their metal is non-conductive, and the wheels area also painted. So It appears that I need plastic axles with conducting, metal wheels that are not painted. Who makes these wheels?

(2) I have heard about making pick-ups from sheet brass that contact the insides of the wheels. But I need to see pictures on how to cut, bend and mount the brass to maintain contact. Any idea where I can find pictures?


----------



## wvgca (Jan 21, 2013)

MtRR75 said:


> (2) I have heard about making pick-ups from sheet brass that contact the insides of the wheels. But I need to see pictures on how to cut, bend and mount the brass to maintain contact. Any idea where I can find pictures?


The Kadee wheels are conductive, works better with smooth back as opposed to rib back style.
You can make or buy wiper kits, low cost alternative is the brass spring used inside Kadee #5 couplers, solder wire to it, then either glue or screw to trucks, image below


----------



## DonR (Oct 18, 2012)

Warren

What a great easy solution. Wish I had thought of
it when I installed LEDs in my Athearn Silver Side
coaches. I wouldn't want anyone to see the
mess I made; but they work

Don.


----------



## Lemonhawk (Sep 24, 2013)

I've used the Kaydee springs to make a single truck pick up from both sides. This was using intermountain wheels.


----------



## MtRR75 (Nov 27, 2013)

Thanks for the pics, guys. The KaDee spring pickups look like they would be pretty easy to do.

As for the KaDee wheels, I tested a new one with an Ohmmeter. I would have to clean the paint off of both the treads and the inside of the wheels. Are Intermountain wheels painted?


----------



## wvgca (Jan 21, 2013)

MtRR75 said:


> Thanks for the pics, guys. The KaDee spring pickups look like they would be pretty easy to do.
> 
> As for the KaDee wheels, I tested a new one with an Ohmmeter. I would have to clean the paint off of both the treads and the inside of the wheels. Are Intermountain wheels painted?


As far as I'm led to believe, the Kadee wheels are pressure / heat formed from sintered powder of some type, and if you look close the surface is not very smooth .. and the Intermountain wheels are supposedly machined, very smooth surface, and I think they are chemically blackened, not painted ..

Fot the Kadee springs, there is a decent step by step page at
http://www.pacificcoastairlinerr.com/1879/bachmann_4-4-0/sound/


----------



## MtRR75 (Nov 27, 2013)

Thanks for the useful link. Hopefully, I will find the time to attempt this in the new year.


----------



## MikeB (Feb 11, 2016)

danpuckett said:


> I have an older unit (DC) that I would like to convert to DCC. It looks like the power comes to the motor off the drive wheels. There is a wire coming off the motor that connects to the tender to complete the circuit through the tender wheels. I do not see any wires coming off the drive wheels to the motor. I assume there is some integral connection deep within the unit. I have not completely disassembled the unit yet. Thought I would see if anybody has worked on a unit this old. The steamer is a 0-4-0 Pennsylvania. It runs good on DC; just wanting to upgrade.


Not sure if this will help you, but I bookmarked this page for when/if I get my old steam engine running. 
http://www.tcsdcc.com/Customer_Cont.../2-8-0 Consolidation/Consolidation_2-8-0.html


----------



## wvgca (Jan 21, 2013)

any older loco without a NMRA plug on the factory light board requires a little more work, and I assume this one has no plug or light board ..While you are at it, you may consider replacing the factory front light [if it has one] with a led, and if you choose to,, you can also add a tender light .. most older small loco's like this didn't come with one ...
and as Lemonhawk noted, if the motor in your loco is the older Pittman style rather than a can motor, performance can be improved by replacing the factory motor magnets with rare earth style magnets


----------



## danpuckett (Dec 31, 2014)

The Digitrax decoder is installed. The isolation process worked well. I put the unit on the DCC track. I have sound, whistle, bell, and headlight, but no movement. I removed the shell and checked the voltage at the motor brushes. There is no power to the brushes even though the throttle is up and the sound is working fine. Either the decoder is bad or I need to adjust a CV to get power out of the decoder to the motor. Thoughts??


----------



## Tom_C (Jan 8, 2016)

I think soundtraxx has a Tsunami2 with 2amp output... but, it's moot since you already ordered a digitrax


----------



## mopac (Feb 24, 2011)

Many times a reset will straighten out a decoder putting out sound but no power to motor.
Have had it myself. Reset was the trick. Have you tried a reset?


----------



## santafealltheway (Nov 27, 2012)

danpuckett said:


> The Digitrax decoder is installed. The isolation process worked well. I put the unit on the DCC track. I have sound, whistle, bell, and headlight, but no movement. I removed the shell and checked the voltage at the motor brushes. There is no power to the brushes even though the throttle is up and the sound is working fine. Either the decoder is bad or I need to adjust a CV to get power out of the decoder to the motor. Thoughts??


i had a very similar problem yesterday.

All sounds were working, but no movement.

Turned out i didn't do a good enough job isolating the motor.

the digitrax decoders seem to have a little circuit breaker in them.

So i took out the motor, covered it with liquid electrical tape, (Essentially plastidip) put it back in, and now it moves just fine.

I would take the motor out, then see if the decoder will spin the motor with no contact of the loco frame.

Make sure you also try a couple of resets.


----------



## wvgca (Jan 21, 2013)

First guess is that you don't have the motor brushes isolated ...

Disconnect the wires to the brushes, and use an old DC transformer or variable supply hooked direct to the brushes and see if the motor turns ...

If so then check to see if both motor brushes are isolated from the frame, by default the old DC steamers with a pittman motor had one brush tied to the motor housing and then to the frame ..

a piece of spaghetti tubing will fix that quite easily, it's not necessary to isolate the motor housing from the frame, just the brushes


----------



## Cycleops (Dec 6, 2014)

wvgca said:


> First guess is that you don't have the motor brushes isolated
> 
> .. it's not necessary to isolate the motor housing from the frame, just the brushes


I have an old Atlas loco where one of the brushes is connected to the motor frame and through the metal chassis, the other is of course isolated. So you need to check carefully as its not always apparent at first sight. As you say that's almost certainly the problem.


----------

