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How do I rewire a DCC locomotive to standard DC?

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Posted by ATLANTIC CENTRAL on Tuesday, December 14, 2010 7:29 AM

rockislandnut,

That's fine, but your statement was easily misinterpreted.

ALL of my comments and recommendations were directed to the OP, except for the general comment about the capacitor - as Rich explained, a VERY well known issue with both DC and DCC if you use other decoders.

Bachmann, and many other dual mode decoders run poorly or barely at all on the DC throttles I use. I use Aristo Craft Train Engineer wireless radio throttles which use pluse width modulation for motor control - just like a DCC decoder. And my own personal testing has confirmed that even with the most "conventional" of DC throttles performance is improved if the capacitors and decoder are removed.

You use DCC, good for you. If he is still listening your mechanical insights into your loco may be of value to the OP. And thank you for the pictures of a DCC version which cleared up some things.

Still the fact remains, if the OP, or anyone else plans to stay with DC, they will see much better performance from their Bachmann locos by removing the decoders, and the noise suppression capacitors - which are also present on some other brands.

Here is the problem with the capacitor. It "softens" or distorts the pulse width signals to the motor. With DC throttles like mine that means the effective starting voltage, and thereby the starting speed, is greatly increased. With DCC, using a high frequency, BEMF decoder both the effective starting voltage/speed is increased and the BEMF signal back to the decoder is distorted, causing very poor response/performance.

If you are happy with the performance of the stock Bachmann decoder, good for you, I wouldn't suggest you change it. BUT many people do and are much happier with their Bachmann locos as a result.

Since I don't use DCC at THIS HOUSE, my experiance on that issue is limited to the five large DCC layouts I regularly operate on, several of which I have helped build and wire. Many of those layout owners have replaced Bachmann decoders/removed capacitors and seen improvements.

And, for two other modelers who use DC, I have removed all the capacitors from all their Bachmann locos and they too report (and I have observed, since I also operate on their layouts regularly) big improvements in performance.

Not everyone who is knowledgable about modern technology chooses to use it, in fact, that's why some of us choose not to use it, we know enough about it to know it's not what we want or need.

Sheldon

P.S. - There is also a DC operator who is very active on this forum who completely removes ALL factory electronics from Bachmann and similar locos, eliminating even the headlights, and wires the motor directly to the track pickups. He too reports much improved DC performence compaired to stock DCC ready or dual mode decoder equiped versions.

 

    

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Posted by rrinker on Tuesday, December 14, 2010 7:25 AM

 It has nothing to do with the fact that the decoder does or does not conform to NMRA standards. There isn't even a 'standard' to how the PWM drive to the motor is handled outside of possibly the maximum permitted voltage.

 A capacitor across the motor will round off square waves. It will damp high frequencies - the cheap DCC On-Board decoders don't use high frequency drives, but better decoders do. The stock decoders are only slightly affected by the capacitor, but the better ones are much more affected.

                             --Randy

 


Modeling the Reading Railroad in the 1950's

 

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

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Posted by richg1998 on Tuesday, December 14, 2010 12:58 AM

Quote:

I know the OP ask for DC and I did not tell him he should get DCC nor would I.

I know the capacitor is still on my engine and it will stay on, that is not for you to say, at least not about mine.

I thought about removing the capacitors but it seems that I'm not going to change the decoder to one that does not confirm to NMRA standards

________________________________________________________________________________

The better replacement decoders conform to NMRA standards. The capacitors and inductors are required on the other side of the pond and interfere with the BEMF in the better decoders. It is a well known issue world wide.

Bachmann sells a lot of DCC on board over there which use the Lenz low end decoder. They work but are low cost to let those with limited finances run DCC. Same in the USA. It is discussed a lot at the Bachmann forums where there is a Bachmann representative there.

Just do a Google search for bachamnn dcc capacitors and learn something about the issue.

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.

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Posted by rockislandnut on Monday, December 13, 2010 10:28 PM

ATLANTIC CENTRAL

"DCC is the name of the game here."

What does that mean? The OP asked about running the loco on DC?

"BTW there is no plastic bag, no three prong jumpers and the only instructions are Bachmanns exploded parts sheet in a PDF, also a page stating CV 1 was #3 and the light on/off instructions."

OK, that's fine, I don't own one, but I do own about 30 other Bachmann Spectrum locos and I operate with DC. I was going by the looks of the drawing published on their web site that it was likely similar to their other locos. I guess space restrictions make this one different, no room for the plug/socket. So I stand corrected on that.

Fact remains if one is using DC, it will run better without the decoder. Especially if the DC throttle uses any kind of advanced pulse width speed control.

And, I see from you photo that motor capacitor is on the motor - that should go for DC or DCC operation.

And still people ask questions about DC and just get told they should use DCC?

Sheldon 

Because it is the name of the game here ( at this house ) and it will remain DCC here!

I know the OP ask for DC and I did not tell him he should get DCC nor would I.

I know the capacitor is still on my engine and it will stay on, that is not for you to say, at least not about mine.

I thought about removing the capacitors but it seems that I'm not going to change the decoder to one that does not confirm to NMRA standards

If it ain't broke, why fix it?

Wadda ya mean I'm old ? Just because I remember gasoline at 9 cents a gallon and those big coal burning steamers.

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Posted by richg1998 on Monday, December 13, 2010 10:13 PM

It would be really nice if the OP would respond. Maybe the person who started the thread does not know what OP means.

I will go with what the OP wants. DC operation without a decoder.

The capacitor and inductors are removed on mine because I am installing a decoder. For DC, they can stay in place.

Anyway, I think the factory decoder install has the decoder wires stuck in the PC board holes with a plastic clip to hold the wire in place. Not sure. Some manufacturers do this. I have not seen the factory decoder install.

Remove the plastic clips and wires. Slip the jumpers in place or solder pins 8, 1, 2 together and solder pins 4, 5, 6 together. That is what the two jumpers do.

The loco has quite a lot of gear reduction which makes it a nice runner.

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.

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Posted by ATLANTIC CENTRAL on Monday, December 13, 2010 9:13 PM

"DCC is the name of the game here."

What does that mean? The OP asked about running the loco on DC?

"BTW there is no plastic bag, no three prong jumpers and the only instructions are Bachmanns exploded parts sheet in a PDF, also a page stating CV 1 was #3 and the light on/off instructions."

OK, that's fine, I don't own one, but I do own about 30 other Bachmann Spectrum locos and I operate with DC. I was going by the looks of the drawing published on their web site that it was likely similar to their other locos. I guess space restrictions make this one different, no room for the plug/socket. So I stand corrected on that.

Fact remains if one is using DC, it will run better without the decoder. Especially if the DC throttle uses any kind of advanced pulse width speed control.

And, I see from you photo that motor capacitor is on the motor - that should go for DC or DCC operation.

And still people ask questions about DC and just get told they should use DCC?

Sheldon 

    

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Posted by richg1998 on Monday, December 13, 2010 7:51 PM

Below is my Spectrum 0-6-0T, DCC ready. I have already removed the inductors and capacitor. You can see the two metal clips. The PC board is clearly labeled. Follow the NMRA color code. I can send you the clips if you really want to go down this path. PM me. Do not put a email address in the forum or put your snail mail address here.

You would do better to solder in a Digitrax DZ125. It is about the size of a dime.

It is an excellent decoder and runs quite good on DC compared to the Bachmann factory decoder.

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.

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Posted by rockislandnut on Monday, December 13, 2010 6:43 PM

ATLANTIC CENTRAL

As others have said, if it came from Bachmann with DCC, it will run on DC.

That said, it will run MUCH BETTER on DC without the decoder. You should have found a small plastic bag with two silver three prong jumpers and a small diagram packaged with your loco.

Using the instructions as a guide, remove the loco shell. This should expose the circuit board which will have a small shrink wrapped circuit board on wires plugged into it. Unplug it - using the diagram insert the jumpers. If your pretty good with electronics, see if you can identify the one or two capacitors on the main circuit board that are arross the motor leads. The motor leads are marked M+ & M- . If you can find these one or two capcitors - remove them as well. you need not do anything but cut or scrape off the capacitors. Reinstall the shell.

Your loco will now run MUCH better on DC and will have much slower slow speed and well as a slower starting speed. If you have any trouble, send me a PM.

Wait until you buy some more Bachmann locos, remove those decoders, then sell the decoders in batches of 3-5 on E-bay :) - they sell well.

Sheldon

DCC is the name of the game here.

Here is my Bachmann 0-6-0T ( shell removed ) engine and it now moves so slow at start up that a snail could run circles around it ( Laugh well almost ). But this is accomplished by adding a drop of "Labelle #108 light oil" on the drive rod pins and a tiny ( very tiny ) toothpick dab of "Labelle #106 Grease ( with PTFE ). Yeah mine was dry right out of the box except for maybe a dash of light grease on the bottom gear, could not see any other grease even with magnification.

Engine out of box had a problem of not wanting to start. LED light both forward and or reverse but no go. I had to just slightly give a push with the throttle on by maybe 4 /6 volts ( running Zephyr ) then it would run to maybe near 30 scale MPH. Not to sure about scale speed and am guessing according to other HO DCC locos of mine with with QSI decoders with speed reporting.

Anyhow the 0-6-0T was a wimp so I checked the contacts to the wheels and all six were terrific shape. Checked under the hood and there it was.

Where the yellow circle is at near bottom of pic the orange and lavender wires to the rear LED were out of their plastic wire holder and rubbing on the back of the gear ( not the teeth but the smooth side. Quite a bit of pressure at that as some of the wires insulation was worn down just a little ( because I ran it for over an hour trying to break it in. Dunce

Where the yellow arrow is near the center of the engine is where I repacked the decoder wires back into their plastic holder but I did have to carefully tape all the decoder wires together for I think the factory way of cramming them in was silly. Also at yellow circle at top of engine was a wire that was completely bare for approximately a 16th of an inch so I taped it so when shoved down to allow the boiler to fit over it as it could get involved with the circuit board.

Now it really runs smooth but at 4.4 ounces do not expect miracles in the pulling dept.

BTW there is no plastic bag, no three prong jumpers and the only instructions are Bachmanns exploded parts sheet in a PDF, also a page stating CV 1 was #3 and the light on/off instructions.

Maybe it will run better on DC without a decoder but its a hassle to remove.

Also notice in the first pic at the rear of the loco that behind the engineers is the DCC decoder and marked Tube.

The person that put this little loco together must have been a tea drinker-------allways on a break. Hmm

 

Wadda ya mean I'm old ? Just because I remember gasoline at 9 cents a gallon and those big coal burning steamers.

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Posted by richg1998 on Monday, December 13, 2010 5:30 PM

I think we lost him

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.

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Posted by sundayniagara on Monday, December 13, 2010 5:08 PM

Why not just run DCC?

http://www.hon3forums.com http://www.americandragracing.com http://www.sundayniagara.com http://www.yorkreunion.com BE THERE!!!!!!!!!!!!!!!!!!!!!!!!!
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Posted by ATLANTIC CENTRAL on Monday, December 13, 2010 1:58 PM

As others have said, if it came from Bachmann with DCC, it will run on DC.

That said, it will run MUCH BETTER on DC without the decoder. You should have found a small plastic bag with two silver three prong jumpers and a small diagram packaged with your loco.

Using the instructions as a guide, remove the loco shell. This should expose the circuit board which will have a small shrink wrapped circuit board on wires plugged into it. Unplug it - using the diagram insert the jumpers. If your pretty good with electronics, see if you can identify the one or two capacitors on the main circuit board that are arross the motor leads. The motor leads are marked M+ & M- . If you can find these one or two capcitors - remove them as well. you need not do anything but cut or scrape off the capacitors. Reinstall the shell.

Your loco will now run MUCH better on DC and will have much slower slow speed and well as a slower starting speed. If you have any trouble, send me a PM.

Wait until you buy some more Bachmann locos, remove those decoders, then sell the decoders in batches of 3-5 on E-bay :) - they sell well.

Sheldon

    

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Posted by jeffrey-wimberly on Monday, December 13, 2010 9:49 AM

This loco has a dual mode decoder. Just put on the track and it should run just fine on DC with no modification.

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Posted by larak on Sunday, December 12, 2010 9:44 PM

It should run fine on DC. Mine does. It's a decent loco but could have slightly better low speed response. Looks nice in the quarry scene.

Karl

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Posted by rockislandnut on Sunday, December 12, 2010 9:30 PM

Robert1441

I have a DC layout, powered by a Control Master 20 from MRC. I just bought a real nice 0-6-0 Saddle Tanker from Bachmann, DCC equipped. I was told I could rewire it to run on standard DC. Something about "Backwards-compatible".

If you could please tell me a good site I can log on to, I have looked at Bachmanns but may have missed it, as to how I can rewire it, I would be most gratefull!!!

Thank you;

Robert

 

Right from the MRR staff, Check it out.

http://mrr.trains.com/en/News%20and%20Reviews/Product%20Reviews/Staff%20Reviews/2010/08/Bachmann%20HO%20scale%200-6-0T%20steam%20switcher.aspx

I have this loco but I run DCC.

Have fun.Yes

Wadda ya mean I'm old ? Just because I remember gasoline at 9 cents a gallon and those big coal burning steamers.

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Posted by locoi1sa on Sunday, December 12, 2010 5:49 PM

Welcome

  If the unit is DCC equipped from the factory then it should run good on DC right out of the box. Is this a brand new loco or did someone put a decoder in it?

     Pete

 I pray every day I break even, Cause I can really use the money!

 I started with nothing and still have most of it left!

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Posted by jrbernier on Sunday, December 12, 2010 5:06 PM

Robert,

  That 'DCC Onboard' decoder should be able to shift between DCC and DC.  If is does not, have someone with a DCC system change CV29 to enable DC.  Have you tried it on your DC layout?  From the factory, the DC enable should be set on.  You do not have to 'rewire' anything....

Jim

Modeling BNSF  and Milwaukee Road in SW Wisconsin

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How do I rewire a DCC locomotive to standard DC?
Posted by Robert1441 on Sunday, December 12, 2010 3:42 AM

I have a DC layout, powered by a Control Master 20 from MRC. I just bought a real nice 0-6-0 Saddle Tanker from Bachmann, DCC equipped. I was told I could rewire it to run on standard DC. Something about "Backwards-compatible".

If you could please tell me a good site I can log on to, I have looked at Bachmanns but may have missed it, as to how I can rewire it, I would be most gratefull!!!

Thank you;

Robert

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