OK, lets see if I can give you some basic information on this conversion. I converted a Mantua Big Six many years ago and the chassis is about the same as yours. I don't remember all the details, but lets see what happens.
The motor brushes have to be isolated from the engine frame. So you are going to have to find out, by looking, how the motor brushes are electrically connected to the frame and tender, and disconnect or isolate both motor brushes somehow. The headlight should also be disconnected. Once this is done, you should verify that neither motor brush is touching or connected to anything on the motor frame, engine frame, or tender by checking it with a meter. If you can not do this or don't know how, stop right here. This project is beyond your level. If you don't get this part right you will blow the decoder. Sorry, that is just the way it is.
I put the decoder in the tender, so I had to run the motor wires from the decoder and connect them directly to the motor brushes. (Orange and gray wires). Then you have to connect the engine frame to the decoder, Black wire. This may require you to drill and tap a hole for a screw to attach the wire to the frame. The tender pick up gets connected to the decoder Red wire. Again, you may have to drill and tap a hole for a screw. Make sure the tender does not get electrically connected to the engine frame, checking it with a meter also. The fiber draw bar may be enough isolation for this. The decoder must be mounted so that any exposed connections or parts on the decoder do not touch any part of the tender.
The basic part is now finished. Put the loco and tender on the programming track and see if you can read the CV's in the decoder. If you can't, that indicates that something may be wrong with the decoder installation. Don't put it on a live track until you can read from the decoder via the programming track.
If everything is OK to this point, you should be able to run the loco on your live DCC track. If it is OK, you can then wire in the lights if you want to or just put the loco and tender back together. You can not use the original light as part of it touches the loco frame. You will have to figure something else out for that. After it is back together, test it once again on the programming track before putting it on your layout.
Hope this helps.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
KMA777
Sorry - I missed the HO part in your first post.
Do you have a multi meter that can read amps? That is the best way to determine what the draw is. If you don't have one you should consider buying one. Meters that are suitable for modeling are quite inexpensive. This is one example from MicroMark but if you shop around you can find them for less:
http://www.micromark.com/digital-multimeter,8150.html
You are correct in that you can put in a higher rated decoder if the motor draw is more than 1 amp. However, the fact that the motor draws so much power suggests that it is not very efficient, perhaps because it is an older design or because the magnet(s) has lost its strength. If it is not efficient it may not pull very well. Both the motor and the decoder will likely run hotter which will shorten their lives. If you exceed the decoder's limits you will let the smoke out of the decoder!
With some motors changing the magnets is easy. The new neodymium magnets produce a big jump in power (pulling ability) and a big reduction in amperage required. The motor and decoder will also run cooler. There is a picture in the thread below of an older motor with new magnets. Go to page 2, second post from the top of the page:
http://cs.trains.com/mrr/f/88/p/120264/2105844.aspx#2105844
The picture shows the new magnets in place. Your motor, if it is the same style, will have only one large magnet. Replacement magnets are cheap. If you want to go that route, ask us and we can talk you through the procedure. My first one took me less than five minutes (with the motor already out).
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Main thing is you have to isolate the motor from the frame. Generally you just need to remove the motor, put down electrical tape or plastic tape etc., and then screw the motor back in place using a plastic screw.
The engine will pick up power from one rail, and the tender from the other. The decoder instructions will tell you which wires go to what, but you'll have one wire going to the engine frame and one to the tender frame, two wires going to the motor leads, and two wires going to the headlight.
Keep in mind you can install a regular decoder now, and later install a sound one. Just remove the old decoder from the 9-pin receptacle you've already installed, and plug in the new sound decoder. Should be plenty of room in the tender for a large speaker and enclosure.
Hi in my post I said HO 4-6-2.. It runs ok on dc. ya would like sound if not a arm and a leg for it. most of what I have read has said that the older loco's have 1amp or more draw and have read that a decoder with 1.5amps would be the way to go. but seen on YouTube ChooChoo3985 that he used a SDH164D in his install into a somewhat like steam loco. wondering if this would be the way to go. best video I have seen on a steam loco decoder install. Thanks for any help.
K
First, it would help if you could give us a little more information. What scale? Do you want sound? Does the locomotive run well on DC? Have you tested the current draw on the existing motor?....
If you are not familiar with decoder installations perhaps the best place to start is by doing some reading on decoder installation in general. Here is a reference page from one of the largest DCC suppliers: (Scroll down to section 2.5.1.6.1. You can read the rest later).
http://tonystrains.com/tonystips/dccprimer/index.htm
Here is a typical manufacturers installation primer:
http://www.soundtraxx.com/manuals/quickstart.pdf
Before you choose a decoder you need to make sure your older Mantua is a suitable candidate. It must run smoothly in DC and it must draw less that 1 amp under full load. The Tony's page can tell you how to test the motor draw.
If it doesn't meet those requirements all is not lost. It is possible to replace the motor, or in some cases just the motor magnets to get the draw down and get it running smoother. A thorough cleaning and relubrication of the motor and running gear is also strongly advised. Make sure the wheels are clean too.
Once you get through all of that, then it is time to choose a decoder.
I am into sound, and I prefer Loksound Select decoders. They work very well and they are somewhat less expensive than most of the other brands, but they can take up a bit more space. Most steam sound installations put the decoder and the speaker in the tender, but not always.
One of the crucial issues is to isolate the motor from the track power. The tutorials explain how to do that.
Don't be discouraged by the apparent complexity of decoder installation. It really isn't all that difficult, however in your case you have chosen a bit more complex installation then most.
Hi I have a older Ho Mantua classic 4-6-2 that is dc and would like to install a dcc decoder. But don't know what decoder to use. Or how to do it been looking around but cant seem to come up with much. what would be nice is a video or pictures on how to do it. Thanks for any help.