Hello everyone, I’m doing my first steps in DCC and I would like to turn my OMI locomotive in DCC. I don’t know how to do it, that’s why I need you help on the procedure. I’ve taken photos and I do understand about electricity and using a tester. It would be greatful any comment you can give me or any web page where it explain how to do it.
It’s HO scale, and I have the following decoders(if non of the are usefull, please tell me which one can be)
DH121D
DH165IP
Photos
Thanks in advance! 
fondo,
I’ve done more than a few OMI’s, so I’ve been down that road before. BTW, only two of your pics show up…the third won’t load.
First, have you ever done a hard-wired decoder install before?
Second, do you want working headlights?
Third, are there ditchlights and do you want them to work properly?
Neither decoder will help you if you want ditchlights. You need a DH163D or DH165D for that. Otherwise, the DH121D would be okay for this loco if you just want front and back headlights. The DH163IP has a plug on it, and would be worthless for this OMI engine (unless it has a plug on it for DCC…and I don’t thing OMI ever did that).
When installing a decoder, the first thing to do in this case is to unplug the lighting, then remove that PCB (printed circuit board) with all the DC lighting components on it. IOW, cut all the wires leading to the board from the various lightbulbs, leaving as much wire as possible on the bulbs.
Before doing anything else, mark the underframe to indicate the forward end either with a marker, scribing it, or some tape.
Next, you have to disconnect the wires from the motor, either by cutting them or unsoldering them from the motor. You may have to pull the motor out to get at the lower soldering pad, or you could try to leave some wire on the motor for a connection later.
At this time, you should also cut the truck wires, leaving as much wire on the trucks as you can. You’ll need them later. You should now have both trucks totally isolated from each other and the motor, with the motor isolated from anything else.
Get the decoder out, and you’ll see it has 9 wires on it: black, red, orange, gray, blue, white, yellow, green and purple (not in that order). Black & red go to the trucks, orange and gray go to the motor, blue is the common for all lighting, white is for front headlight, yellow is for rear headlight, green is for Function 1
wow Paul thanks for your answer.
Yes it’s my first time doing this so I will have to read and re read what you wrote me. Is there any image that illustrate how to wire everything?
Thanks!
There should be a diagram with the decoder, but here’s one from the Digitrax website:
http://www.digitrax.com/v1/ftp/ditchlights.pdf
Note that the bulbs used in this example in the pdf file are 12v bulbs while OMI uses 1.5v bulbs. The OMI bulbs need a resistor to knock down the voltage to acceptable limits, at least with the DH163 and DH123 decoders. The DH165’s may or may not. I haven’t done much with a DH165D yet, but some DH165’s seem to have current limiting resistors built in (like the DH165AO, which is a board replacement form factor rather than shrink wrapped).
Paul A. Cutler III
his third pic:
Thanks for showing the picture!
Do you think that in can be a start point trying to make work the decoder just for moving the loco and then try with the light?
Also which resistor should I use?
Take a pic of the other side of that circuit board there.
Also check to make sure that the motor is electrically isolated from the chassis. If it isn’t you’ll have to insulate it with electric tape.
how do I check the insolation? I can not take a pice from the other side beceause the cable length doesn’t allow to turn it
Use the ohms scale of your multimeter. Trying to do this at this level without a meter will be difficult for those who do not understand electrical.
There should be no electrical path between the frame and either motor contact. I use Kapton tape from Litchfield Station. This is a tough thin tape. Make sure you cannot see any wire from each motor contact touching the frame anywhere.
Below are some useful links about DCC. Take time to read though then as it will enhance your knowledge of DCC.
http://www.members.optusnet.com.au/nswmn2/DCC.htm
While this will not exactly answer all your questions for this particular loco, you will have a lot fo useful DCC info for the future. There are basic NMRA wire codes for DCC and the info is in those links.
Rich
Based on your questions I think your first step should be to buy the Kalmbach book on DCC and study it. Hardwiring a decoder into a brass loco for your first try is a big and potentially difficult job for your first. The info you have been given thus far, while accurate and probably helpful, I feel may be a bit over your head. Just my perception. Good Luck.
From what I can see, mounting the decoder securely will be a bit of a challenge. No doubt have to make a support shelf over the drive shaft to mount the decoder. I have done something like that in a Spectrum 70 ton but I was able to put styrene shelf in place for the decoder and a small piece of copper clad PC board to minimize wire splices. I have some Vero board from the UK I picked up some years ago for various electronic projects.
I then followed the instructions that came with the decoder. Many sue 1 k resistors but a few use maybe 2k for ditch lights as they thought with 1k, the lights were too bright but it is your railroad.
Below is what I did for my loco as an idea. I have used this PC board in other loco conversions.
Rich
Of the two decoders you mentioned, the DH121D would work, but not if you want ditch lights along witht he headlights. You’ll need a better option - the DH165IP is a decoder designed to plug in to an 8 pin socket, you need to hard wire this one. A suitable DIgitrax decoder that has enough functions to do the ditch lights and all is the DH163D. The TCS T4X would also work - unless you have a rooftop beacon as well at the ditch lights and headlights, in which case you’d need the T6X.
Bottom line, you need a wired decoder that has enough functions to handle all your lights you wnat to include. Front and rear lights are two functions, ditch lights need another 2 if you want them to flash alternately, and then a rooftop flasher or whatever would be another. Too many choices to list them all.
–Randy
fondo,
If you read my post, that’s exactly what I suggested. You really should make sure the engine runs properly before tackling the lighting. Once the engine runs, the lighting can be done later or not at all. Your choice. But you need the motor done first. As for which resistor, I usually use a 680 ohm as I said above.
Hamltnblue,
Please don’t confuse the guy. For one thing, the motor itself does not have to be isolated from the frame, only the motor brushes (or contacts) have to be isolated. Secondly, it’s an Overland. I’ve yet to see any Overland where the brushes are not isolated, and I’ve installed DCC in perhaps a couple dozen OMI’s. So fondo, don’t worry about it with this engine.
richg1998,
This decoder mount is not structural. He doesn’t need to fabricate a big styrene shelf. A simple piece of Magic Tape holding the decoder to the top of the motor will work fine as long as the wires don’t drag on a flywheel.
If anyone is really concerned, there’s a little trick one can do with these OMI’s. The PCB the diodes were on that came with the model makes a great shelf for the decoder. Strip off all the components that are on the PCB with nippers. Tape the decoder to the PCB, then screw it on to the shelf bracket. Viola! Instant mounting for the DCC decoder.
Paul A. Cutler III
Thanks Hergy, richg1998, rrinker, Paul3 for yours replies!
So I will try to get the correct decoder as YES I want ditch light working WITH flash alternately, and what I forgot to say, is which decoder can do this? (DH165d?) and also can have the option to include sound in the future??
I’ve seen that Digitrax has a sound decoder for AC4400 but for Kato, would you recommend me this sound or better from another brand?(here in Argentina is not so simple to get all brands)
THanks again for your replies…
If you want a better sound option, Soundtraxx has a Tsunami with the appropriate sounds for the AC4400 and QSI also has one with the proper sounds. Either one will be better overall to the currently available sound files for the DIgitrax decoders. Both are motor plus sound, so it’s the only decoder you need. ANd they both have enough function outputs to provide the ditch lights - and if you want they will even work with the horn, so when you blow the horn the ditch lights will start flashing, and kep alternating for a set time afterwards, when they will revert to both just being on - this is how they operate in my part of the US anyway.
–Randy
I would contact Litchfield Station for decoders. I do know some in the UK and the EU have bought from this company and they do answer email. Let them know where you live. There are different form factors for decoders. Litchfield pretty much spells out everything.
http://www.litchfieldstation.com/DCC-University/index.htm
Decoder mounting might be different depending on which decoder you are able to purchase.
If you had to build a shelf for say a light board type decoder, there are many different sizes of styrene.
Some decoders come with 12 volt light connections for bulbs and LED’s and 1.5 volt connections for 1.5 volt bulbs on the same decoder. As was said, a resistor for the LED. One decoder includes LED connections with the resistors on the decoder.
I use a double sided tape from Litchfield that works very nice and can still remove the decoder if there is a problem.
There are some different ways to do this. Post some photos when the project is done.
RIch
Thanks rrinker, but if I want first a decoder just for locomotive fuction which one can be that later I can add sound? or it’s better to leave that decoder for another loco and buy sound+decoder together?
Also my shop here, doesn’t have the DH165D, just the IP one. Does NCE, TCS have a similar decoder?
In case you do not have the sites, below are the NCE site and TCS site links. Usually all the specs are shown.
http://www.tcsdcc.com/public_html/index.php
Again, the Litchfield site will show many different types of decoders with specs even if you do not order from them.
Rich