DCC Decoder in Kato N Scale F7

sdlink Nov 29, 2014

  1. sdlink

    sdlink TrainBoard Member

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    I am new to N scale and trying to install my first dcc decoder (I have done many dcc decoders in HO scale). I thought I ordered the Digitrax decoder that Kato's website directed me to-the DN163K0b decoder but when I pulled the shell off things weren't as the decoders directions directed. I was expecting to find a light board to replace but instead I was greeted to this all-metal frame. Is there any way to put a decoder in here or no?

    [​IMG]

    This is what the decoder looks like:
    [​IMG]
     
  2. Arctic Train

    Arctic Train TrainBoard Member

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    Kato made a non-dcc frame a while ago. Unfortunately, the decoder you purchased is meant for the newer DCC ready frame style. You mentioned you have installed decoders before and that may be good news. If you are adept at milling a frame, you can stick a wired decoder in it. Digitrax recommends one of the following: DN135D, DN136D, DZ123, DZ125, or DZ143.


    Brian
     
  3. mfm_37

    mfm_37 TrainBoard Member

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    Yep, that's the first run non DCC mechanism. The frame will need to be cut and a wired decoder installed. This was one of my first years ago. Should be easier now with today's small decoders. If you want to cut it yourself, the decoder goes in the rear after removing enough metal for it to fit. You will also need to cut some grooves to run the wires to the motor brushes and the front head light.
    Aztec will cut the frames for you at a reasonable price. http://www.aztectrains.com/dccframes.html
    He also has instructions for installing the decoder in the modified frames.

    Martin Myers
     
  4. nscalestation

    nscalestation TrainBoard Supporter

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  5. sdlink

    sdlink TrainBoard Member

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    Thanks for the feedback on this guys. I've done some research and feel fairly confident I can mill the frame and install a dz123 by myself. I think it will be a fun project.
     
  6. sdlink

    sdlink TrainBoard Member

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    Just one question though, what's the best way to isolate the motor?
     
  7. mfm_37

    mfm_37 TrainBoard Member

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    I'll try to remember because it's been at least ten years since doing any of these. I have sold them off since then so can't tke a look for a refresher.

    I believe you need to remove the brush caps and the brass contact strips that are connected to them. Be careful as the springs will fly. I do mine inside a transparent plastic bag so the flying small parts stay in the bag. Solder the decoder wires directly to the brush caps. Then reinstall the brushes, springs, and caps. You will need to machine some clearance around the brush caps and wires and also cover the exposed connections with Kapton tape. Machine grooves for wire to run in.
    I mounted my decoders in the rear at the top by removing metal to fit. IIRC, i installed DN93 decoders. Should be much easier today as DN93's were huge compared to today's decoders. I used half wave power for the head light so that only the white wire was required. That area is tight if you re use the factory light board.

    Martin Myers
     
  8. sdlink

    sdlink TrainBoard Member

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    Ok I tried the installation today and when I put it on my track and turned track power on the power automatically trips off. No smoke or burning smell from the decoder. Any ideas what might be causing this?
     
  9. r_i_straw

    r_i_straw Staff Member

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    Sounds like a short somewhere. I always test with a 9 volt battery before I put the shell back on. If the decoder has the analog enabled, the two battery contacts making touching the frame halves, the motor should turn and the light come on. An old 9 volt battery that shows only 7 to 8 volts on a meter usually does not have enough current to fry anything. Maybe a pinched wire between the chassis halves or at the light board.
     
  10. Carl Sowell

    Carl Sowell TrainBoard Supporter

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    sdl,

    let me throw my 2 cents worth into the pot. I just recently installed DZ 125 or 143, I don't remember which decoder, into two of the older KATO, non dcc, chassis. I did as Martin and milled enough space above the rear gear tower. Don't go too deep and compromise the bearing blocks. I then beveled the top of the two frame halves to create a grove for the wiring to lay in. I soldered the motor leads to the brass motor contacts and put it all back together. A short, of course. What I failed to think of and do was to install Kapton tape on the inside of the chassis where the motor contacts touch the frame. I put Kapton on every nook and crannie in the area and no short. The next one I did I milled out the side of the frame and made it more like the open frame style now used. Still applied Kapton tape around the top of each frame half, just in case, no problems.

    The three older F-7's pull much more than the new versions.

    Carl
     
  11. woodone

    woodone TrainBoard Member

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    I always remove some of the metal material that is where the brush caps come close to. I remove enough metal so I don't use Kapton tape. I also cut the brush cap copper leads very short and keep the wires close. Before I put everything back together I test each motor lead to the frame to make sure I don't have a contact touching causing a motor to frame short. I have found more that once I had a motor lead touching the frame.
     
  12. sdlink

    sdlink TrainBoard Member

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    I really appreciate all the help guys. I've done almost all the steps you've suggested-ground out slots in the frame to run the motor wires, used Kapton tape to isolate the motor. I can't seem to find a short. The one thing I am wondering about is if I damaged the light board when I was soldering the wires to it. Would that cause an issue? I was wondering if I could remove the light board and all the wires and try temporarily attach the power pickup wires of the decoder directly to the side frames and see if it works that way. Is that safe to do? Will that tell me if the light board is damaged?
     
  13. r_i_straw

    r_i_straw Staff Member

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    Sounds like a plan. If you want you can just remove the motor and light board from the chassis, still attached to the decoder and provide power to the red and black wires. That will show if the motor goes round and the headlight illuminates.
     
  14. sdlink

    sdlink TrainBoard Member

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    Ok so I've tested everything with a 9 volt battery and everything works. I wired everything back up and put the battery leads to each side and the light works and the motor spins. When I set it on the track and turn the power on same thing-the light flickers and the digitrax zephyr shuts off. I tried reading the cv's on a program track and I get the d nr reading meaning the decoder can't be read. I took a video of the zephyr and loco kicking out but I'm not sure how to upload it.
     
  15. sdlink

    sdlink TrainBoard Member

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  16. Carl Sowell

    Carl Sowell TrainBoard Supporter

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    sdlink,

    I am, by no means, an expert and BTW you have had some replies from guys that I would call experts, for sure. Having said that, I have an observation or two and questions for you.

    I don't think you ever mentioned which decoder you went with the second time but in your video it appears to be a Digitrax DZ 143 or something like that. I see a yellow wire flowing towards the rear of the chassis, so it must have outputs for front and backup lights. I see a red and a black wire that looks to be connected to the light board. I also see what looks like the white wire is connected to the light board but I do not see a blue wire attached that would be necessary to complete the headlight circuit. My 74 year old eyes may not be able to see it but even when I expand that photo I don't see it. My first thought is that the problem comes from that light board, may be wrong of course.

    So, my first question is can you please give us a brief explanation of how you wired to the light board? Depending on what you wanted to do, you may have needed to cut the traces. Did you check the light board soldering to make sure a little wire or spec of solder did not flow over and contact both contact points. Go ahead, ask me how I know that problem. Duh, I never read "soldering for dummies".

    My other observation is that the space between the two frame halves appears to be normal and ample width to keep from shorting. However, and it may be the angle of the picture, the rear space appears to be quite narrow. I am assuming that you did put the plastic insulators between the frames, at the rear as well as front. Even if the insulator is installed at the rear, is it possible that the frame is warped a tad and is making contact with each other? I have had warped frames before.

    Perhaps we can help solve the problem. Woodie, Russell any thoughts?

    Carl
     
  17. woodone

    woodone TrainBoard Member

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    How well did you clean up the frame half's? Also look at the frame spacers. Make sure you don't have a metal shaving stuck in the screw hole of one of the spacers.

    Carl, we don't need the blue wire for powering up the front LED. We can use the right or left rail terminal to power it.

    Still need a resistor. This will provide 1/2 wave power to the LED with out running the blue wire to the LED.
    Make sure you did not bridge a gap when you soldered your power leads to the light board.
     
  18. Carl Sowell

    Carl Sowell TrainBoard Supporter

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    Woodie, that's all well and good, however when you look at the still image of the vid, the light board area looks extremely full of something. I still put my money on the light board or maybe as you suggest there are some filings left over from grinding on the frames.

    carl
     
  19. woodone

    woodone TrainBoard Member

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    Carl, That board is very small in that unit. Like you my eyes can't see just what is soldered where so it is hard to tell what might be wrong. Very easy to have a short and not be able to see it. I would just start by ringing out every connection.
     
  20. sdlink

    sdlink TrainBoard Member

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    Ok so I had some time to take some pictures of the install last night. I should start this post by saying that I think the decoder is friend. It isn't responding to anything now so I will have to get another one.

    Here is a picture of the board after making the cuts in the circuit trace as well as after a few attempts at soldering:
    [​IMG]

    This is how I originally had everything wired up. Originally I had the white and blue wires soldered together and soldered to the board at the same point. Then I read on aztectrains.com that they didn't use a blue wire so my second attempt I only soldered the white wire on. Which is correct? Do you see anything wrong with the way these wires were soldered to the board?
    [​IMG]

    This is how the frame was milled and how the kapton tape was installed:
    [​IMG]
     

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