DCC Decoder in Kato N Scale F7

sdlink Nov 29, 2014

  1. sdlink

    sdlink TrainBoard Member

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    The next few pics show everything as it was installed:
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    Here is the rear:
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    Front:
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    This photo shows a question area for me. I didn't notice this before but if you look at where the end of the tweezers is pointing you see the top brush cap where the motor wire is soldered to. It looks like it could have touched the frame here.
    [​IMG]

    I really appreciate all the help you guys have offered so far. I thought I did a decent job milling the frame and creating space for everything but apparently I did not. My two areas of concern are that last photo with the top motor brush wire as well as the soldering job on the light board. The light board itself still works if i put a 9 volt battery to the light as does the motor.
     
  2. Ristooch

    Ristooch TrainBoard Member

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    I definitely think that your last photo reveals a potential short. In my opinion, you should enlarge the opening at the top brush cap. In reading the earlier post, I would also think you need both blue and white for your headlight to work. I recall that Lenz showed a slightly different wiring setup, but I have always used the blue (common to the positive side of the LED) and white (forward headlight) and yellow (rear headlight) in my wired installations.

    You may also want to look at your soldering on the headlight board and confirm that none of your solder joints touch the frame.
     
  3. sdlink

    sdlink TrainBoard Member

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    Paul, so are you saying this is how it should have been wired:
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  4. woodone

    woodone TrainBoard Member

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    I am not sure why you have the black wire soldered to the center of the board. It (the black wire) should make contact with the pad on the right side of the last photo. Can't see the other side of the board to see the traces to tell where each trace runs. This is how I see you need to wire this. The red wire is to the pad on the left side of the photo There should be a trace that runs to the resistor should run to one side of the LED, This is the plus side of the LED The white wire goes to the other side of the LED. The black wire goes to the pad on the right and no where else. Best I can do with our seeing the other side of the board.
     
  5. Carl Sowell

    Carl Sowell TrainBoard Supporter

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    sdl - thanks for the excellent images. If I may offer my thoughts.



    Look at your post #20, the last image. It appears to me that the Kapton tape is not adequate to cover the motor bay area from top to bottom of the bottom frame.
    I think you sort of saw that and mentioned that later in your posting.

    Look at your post #21, the second image top side of the frame (left in photo), the cap appears to be too close to the frame.

    Also, post #21, last image, I agree with what you said regarding the cap and frame and agree with what Ristooch suggested.

    If you look at the image that shows the right side frame with everything installed I think you can see that the white/blue wire soldering is or seems to be touching the bare frame. Possibly the problem area.

    Now, I want to make a comment about wiring the headlight and I would like for anybody, that knows from first hand experience regarding using only the white wire, to correct me. As Ristooch, I have always wired LED head or backup lights with blue, common, to + side of the LED with an appropriate resistor and the other LED lead connected to the white, headlight or yellow backup light. I have always read that LEDs must have a resistor because my guess is the decoder puts out somewhere around 12 volts for the lights and typically the LED's are in the 3v range. In my humble opinion, with the blue and white wired/soldered to same spot a direct short was created when installed in the frames. If the light board is removed from frame and a battery attached, you probably can't have a conflict ? ? ? ?

    If I was you, I would acquire another light board and start over. If you do not have anymore lightboards and if yours is numbered 77A, send me a PM with your address and I will send you three boards. As info, I do not use that method of adding lights. I purchased very small (pico) LED's from Evan Designs that have a bridge rectifier and a resistor ( both very small ) already wired. I glue the LED to the light tube and then connect the wires to the appropriate decoder wire For the red and black pickup wires, I tap and thread a hole for an .0090 screw, in the top of the frame where the board would normally sit. I use a .0090 washer and screw the wires to the frame. Very positive connection and no Atlas style pickup problems.

    Just my two cents worth and thanks for letting me ramble. Perhaps this will help you find your short.

    Carl
     
  6. r_i_straw

    r_i_straw Staff Member

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    This is how I wire all mine. The LED has to be removed and turned around. On the underside on the engineer's side, cut the foil across close to the resistor. The LED works just fine running on half wave (plenty bright).
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  7. woodone

    woodone TrainBoard Member

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    Carl, like you said if the blue and white wires were soldered to the same pad there would be a short, but only if you tried to turn on the light. If that was done I would guess that this would have taken out the transistor in the lighting circiut for the front light.
    As for using a the blue wire for powering lights. Yes that is a correct way to do that. But you can also power the LED via either the right rail or the left rail pickups. This will deliver 1/2 wave dc pulses to the LED and you must still use a resistor. I have done many headlight like this. Saves running one more wire you really don't need.

    The Kato Mikado's I do this way as it saves running a 6th wire from the tender to the loco. Done so many I have lost count.
    Wish that I could blow up the photos to see thing better.
    The brush caps look like a problem. Kapton is good stuff but was not meant to be a tough tape, it can be torn or pierced very easy. Easiely piereced via a stray stiff wire.
     
  8. Carl Sowell

    Carl Sowell TrainBoard Supporter

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    Thanks Russell, if that one you posted is the board in question, than the ones I offered are not the correct ones. If you have a pic of the other side, could you post it as well. I see what you are saying but I just can't visualize the back side. That is my 74 year old mind at work or possibly resting. How was the OKC Show this year?

    Woodie (J---y), I still am having problem understanding the white wire only concept but don't worry about trying to explain as I will stay with what I know. In this case, there would not be a problem running one more wire on the F-7. You mentioned the Mike's, uhm, I still have not messed with mine and now I have another AC-9 boiler and project on the drawing board plus I may do an SP GS-1 casting on a B'mann J Class 4-8-4. Glutton for punishment, I guess.

    Carl
     
  9. r_i_straw

    r_i_straw Staff Member

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    On the image that I posted, the brown areas are where the foil is plated to the opposite side. The green is where it has been etched away. So it is basically a mirror image of the bottom side. The resistor is on the other side across the top of the board between the two clipped off leads that stick through the board. An alternate way to do it would be to just clip the LED lead going to the left (fireman's) side, bend it up and solder the white wire to it. For decoder operations, the white and yellow wires are electrically "floating" and just go to ground when they are enabled. The blue wire provides + DC voltage to run an LED or a bulb. The power coming up to the red or black wires is a "square" wave so the diode will only light up when the wave swings to positive. That happens many times a second so your eye does not see the LED flashing.

    The OKC show was a blast as usual. Different building at the State Fair venue for the first time as the old one is being torn down.
     
  10. RedRiverRR4433

    RedRiverRR4433 TrainBoard Member

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    Carl:

    On all my Kato Mikado's, I only use the white wire to power the front headlight. The blue wire isn't necessary. By only using the white wire, only five wires pass from the locomotive to the tender, not six. Try it and have fun with it. It's an easy installation if you follow the directions carefully.:cool::cool:


    Shades
     
    Last edited by a moderator: Dec 13, 2014
  11. sdlink

    sdlink TrainBoard Member

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    Hey everyone I thought I'd give an update on this project. I picked up a new dz123 and wired it all up again after milling some more areas off the frame to provide extra clearances for wires.

    I soldered the motor leads and the blue/white wires to the light board and just temporarily Kapton taped the red/black pickup wires to the frame. I didn't install the light board in the frame. Tested with a 9 volt battery and everything worked. Put it on the program track and couldn't read any cv's. So I un-soldered the white/blue wires from the light board and just left them loose. Tested again and everything worked great.

    Obviously the problem is in the light board which isn't too surprising because I think I botched it up in my first attempt at soldering.

    Carl was very gracious and sent me what we thought were a few similar light boards but unfortunately they are not a match. I called Kato and they don't manufacture this light board anymore so I either have to go without a light, learn how to wire up a light on my own without a board, or go on the hunt for another old f7, or a Kato Mikado or HO NW2 as they also used this light board.
     
  12. Carl Sowell

    Carl Sowell TrainBoard Supporter

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    Sorry bout that Ryan. Did not think they looked right but use them for whatever.

    C
     
  13. woodone

    woodone TrainBoard Member

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    An N scale Kato Mikado light board will not work.
    Maybe you could rework the Mikado light board to fit but you will have to shorten it up a bunch.
     
  14. sdlink

    sdlink TrainBoard Member

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    I was just going by what I was told from someone at Kato USA. They thought the Mikado light board was the same, good to know that's not the case so I don't waste my time searching for one from that source.

     
  15. drgwspup

    drgwspup TrainBoard Member

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    I was doing some research on how to hard wire a TCS M1 decoder into a non-DCC Kato F unit and also include a Gyro light with the headlight. I came across your series of posts from several years ago.If you recall the individual was struggling with how to wire the light board and the decoder.

    I was going to do as you suggested and drill/tap/screw the track wires directly to the frame. Great idea rather than sending wires all the way up to the front of the unit to only then rely on the friction fit of the light board into the chassis frame.

    I have two questions with respect to how you attached the lights.

    On the Evan Designs website it says to not connect the LED Pico kit to the DCC decoder because the function output operates at very low voltage. But my research shows that the TCS M1 function output is at 12 volts. So I think I am good there, correct?

    What glue did you use to attach the pico led to the light tube?

    Thanks in advance,

    Mark, P

     

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