DCC for Microtrains SD40-2

Cactus Aug 17, 2019

  1. Cactus

    Cactus TrainBoard Member

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    So, I bought one of these locos last month, and have just obtained a Digitrax DZ123MO decoder for it. The thing is installed into the loco -- meaning it fits and I have attached the springs. But, the loco doesn't respond on the tracks.

    I did a search that showed folks having some frustration with this install back in 2010.

    Can anyone point me in the right direction to get a decoder installed in this loco?

    Here's a photo of the install so far. IMG_4062.jpeg
     
  2. tjdreams

    tjdreams TrainBoard Member

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    From the looks of the picture the decoder is not instaslled correctly the Springs should be connected to the pads lthat are set in a little left of where they are now. Ther decoder needs to slide to the right a little more so the mounting risers are making contact with the other 4 pads

    Should look simular to this 20190817_191945 (Medium).jpg

    This is the same DZ123MO decoder installed on my MTL GP9
     
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  3. tjdreams

    tjdreams TrainBoard Member

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    Before aplying power make sure the springs are not making contact with the chassis.
     
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  4. Cactus

    Cactus TrainBoard Member

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    tjdreams, thanks for the suggestion. If you look carefully at the photo I posted, you will see that the frame on my loco is not the same as the frame on yours. My decoder can't be installed as you suggest. However, your photo is very interesting. The frame on your loco appears to be making electrical contact with 4 pads on the board that are freely visible on mine, and that your springs are attached to a different set of pads than I have done.

    My question is, does your frame actually contact those 4 pads? If so, I could wire an attachment from those to the frame and relocate the springs to the forward set of pads and that should do it. Here's a photo to show what I mean. Would that be correct?
    IMG_4062a.jpg
     
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  5. tjdreams

    tjdreams TrainBoard Member

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    Yes the 4 pads are making contact with the frame. And the springs are connected to the forward pads. at least thats the way it is on my GP9's and GP35's

    Your picture has me courious. I have a SD40-2 that i was planning to put a decoder in. Guess i'm going to have to order one and give it a try.
     
  6. markm

    markm TrainBoard Supporter

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    Sometime after 2010, MTL changed their chassis for SD & GPs from a forward facing side frame clip to an inward facing. Prior to withdrawing it from the market, TCS recommended cutting off the top of the clip and soldering the board in place. I've seen no modified installation for the DZ123M0 board.

    Looking at the images, it seems that the rear headlight SMD is blocked by a frame clip on the new chassis. It would seem that either one would need to cut that clip or remove the LED and wire around the clip.

    Mark
     
    Last edited: Aug 19, 2019
  7. Cactus

    Cactus TrainBoard Member

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    Thanks. I hope to leave the frame alone. Perhaps I can find a way to route wires to the right places. It won’t hurt to try.

    I would rather risk damaging a $30 board than a $130 loco. ;)
     
  8. Cactus

    Cactus TrainBoard Member

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    In case anyone is interested, I contacted NCE about their MZA4 decoder, which was an easy install in this locomotive. Here is the response:

    From: Dan - Tech Support <techsupport@tcsdcc.com>
    Subject: Re: MZA4 replacement?
    Date: August 19, 2019 at 1:44:46 PM EDT


    We are looking to re-design this product and re-release it in the near future. Unfortunately I do not have a timeline on when this might happen. You may still be able to find MZA4 decoders out in the wild from other dealers or resellers from our initial run(s) of those decoders.

    Regards,

    Dan

    Technical Support
    Train Control Systems
    P.O. Box 341
    Blooming Glen, PA 18911

    Phone (267) 733-3408
    Fax (215) 257-0735
    techsupport@tcsdcc.com
     
  9. tjdreams

    tjdreams TrainBoard Member

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    After pulling out a 1st gen SD40-2 and compairing it to the 2ng gen It's clear that what changed is the PCB.
    unfortunitly the side by side pic's i took didnt turn out.
    The new PCB has 4 springs soldered to the underside pads so they make contact with the top of the frame instead of the 4 risers or mountung tabs. I had a DZ123MO with burned out LED's so i decided to try my hand at removing the 4 springs and LED's from the stock 2nd gen PCB and soldering them on to the decoder. Which i'm happy to say worked out rather well

    The first image shows:
    the 2nd gen PCB with LED's and springs removed (top)
    the first gen PCB still mounted on a first gen frame (middle)
    a DZ123MO with LED's and springs from the stock 2nd gen PCB (bottom)
    20190819_182840 (Medium).jpg

    2nd picture shows
    A side view of the DZ123MO with LED's and springs from the 2nd gen PCB (top)
    A side view of the first gen PCB on on a first gen frame (bottom)


    20190819_183644 (Medium).jpg

    3rd picture shows
    my DZ123MO with springs and LEDS from the 2nd gen stock PCB mounted on the 2nd gen frame.

    20190819_192055 (Medium).jpg

    4th picture
    As you can see the spring indent mounting tab/hole on the decoder is not aligned over the motor tab. Unfortunitly when trying to install the orignal motor contact springs this misalignment causes them to make contact with the side of the frame which inturn will short out the decoder.
    The workaround for this should be simple enough. I intend to solder a short piece of insulated decoder wire between the motor and the motor contact tab on the decoder.

    20190819_195541 (Medium).jpg

    Well thats it for tonight.


    David
     
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  10. Cactus

    Cactus TrainBoard Member

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    I finally got the time to install the DZ123MO into the locomotive. I took the obvious route, which is the same as the one that tjdreams used in the post above, except that I transferred only 5 of the 6 springs. Only 5 because one broke. It appeared to be broken in the original factory install, but held in place by a blob of solder. It fell apart as soon as I touched it with the iron. I substituted a fine piece of wire for the broken one. I used a bit of Kapton tape to insulate the motor springs from the frame.

    The loco runs fine now on DCC, with the complaint that the LEDs on the new board light up enough to shine through the shell. At some point, I reckon I will take the shell off and paint it black inside.

    What was supposed to be a drop-in board turned out to require some soldering and taping, but it works fine. I caution folks that a person should be adept at soldering small wires to printed circuit boards before doing the mod.
     
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  11. husafreak

    husafreak TrainBoard Member

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    I just bought an MTL SD40-2 and I might try to install a DCC board in it. I don't know if it is a 1st gen or a 2nd gen loco. Is the DZ123MO the correct DCC board for either of these versions, just requiring modifications as shown here? Or are there different boards depending on which loco?
     
  12. Cactus

    Cactus TrainBoard Member

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    I bought my SD40-2 last August, so I'd say it's second gen. As I posted above, I had to make the springs/kapton tape mod to install the DZ123MO board. The DZ123MO was at the time (August) the only so-called drop-in board for that loco. I suspect that the DZ123MO was developed to fit the first gen loco. but I have never seen one of those. It was a pain to make the board swap, but my loco works fine.
     
  13. husafreak

    husafreak TrainBoard Member

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    OK so same board either way. I bought my loco at a LHS going out of business sale, no guessing its age.
     
  14. markm

    markm TrainBoard Supporter

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    I'm not sure there is a 1st/2nd generation for the SD40. The GP frame clips were originally oriented as in David's image. About the time the SD40 was originally released, they were changed to face inward. I have an old SD40 I can check, but since MTL Joe said there were no changes with the new run, I'm assuming it hasn't change.

    Freak: I know your unit. It was ordered the same time as mine and it's definitely the 2018/19 chassis.

    Mark
     
  15. husafreak

    husafreak TrainBoard Member

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    Thanks. I think I’ll try to put DCC in this loco, to try a Digitrax unit. And (off topic) I’ll get a couple of TCS boards for a pair of AZL loco’s. I’ll learn the NCE DCC system, and dream of running my little consist on the greatest AZL track in North America, the BazBoy’s!
     
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  16. markm

    markm TrainBoard Supporter

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    A couple of suggestions. Start with DCCing an AZL unit: it's easier and there is less fiddling with CVs. Start out with a simple oval test track to minimize possible layout issues. The Power cab expects to mount the interface panel n a layout panel. For portable use, I mounted a panel on a plastic box with a screw panel for the wall wart.
     
  17. husafreak

    husafreak TrainBoard Member

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    Thanks, I’ll do that. Success instills confidence!
    I miss those “project boxes” and wiring boards Radio Shack used to sell. They would be handy for this.
     
    Last edited: Dec 7, 2019
  18. husafreak

    husafreak TrainBoard Member

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    IMG_8897.JPG IMG_8897.JPG IMG_8898.JPG IMG_8901.JPG IMG_8904.JPG

    I finally got to DCC my MTL SD40-2 with the Digitrax DZ123MO board yesterday. My pictures are not really different than what was presented before. The process was complicated by misunderstanding mechanical bearing fitting in the loco chassis, not by the electronics! So I wanted to explain that. I'll do a brief how to:

    The manual supplied with the DZ123MO shows installation in a MTL GP-35, this is a "slide in" install like a current AZL loco I did. But on my MTL loco, like the one the OP Cactus showed, the board is held in from the sides. So in this case the chassis halves have to be separated to allow the removal of the stock board and insertion of the DCC board. This is where I went wrong. I just pulled them apart a couple of mm to swap the boards, allowing the internal drive parts to move out of correct position. Please note that this is my first MTL loco and I like to learn everything the hard way. Why? Because those are the lessons you never forget!
    So, assuming your chassis is the same as the one initially pictured here by Cactus, separate the chassis halves and remove the stock board. Unsolder and transfer the springs to the DZ123MO. Choose the chassis half with the "notches" for the plastic driveshaft bearings and place that on your work surface. Carefully locate the motor and drive shafts ensuring that the keys on the plastic bearings are set into the notches on the chassis half, insert the board into its holders on that side and then press the other chassis side down onto everything with great care so that it captures the board while not upsetting the bearings. Then finish the job. Use capton or electrical tape to ensure electrical separation between the motor springs and the board spring contacts, or just solder the motor to the board with insulated wire as suggested above.

    In the interest of full disclosure this is what I did wrong: I did not fully separate the chassis halves and so the bearings did not correctly seat, tightening the frame screws pinched the bearings and drive shaft, and while the lights would work indicating a good board the loco would not move. I then decided the frame sides were not close enough together (you can see that in photo 5) but I thought the width of the new DCC board was preventing the frames closing fully so I separated the sides and filed the chassis board notches deeper. When I went to reassemble the loco I saw the keys in the plastic bearings. I then correctly reassembled the loco. But the deeper notches allowed the board to move slightly in the frame and for the electronics to make unwanted contact. The loco was not responding correctly on the track. I found the unwanted contact between a frame clip and one of the SMT components. Separating the halves again and trimming away a half mm from the frame clip solved that and the SD40-2 is running well now. But in any case they are very close together so watch out for that.

    I will try to install light pipes at some point as the light from the DZ123MO LED's is very dim, It makes for a nice effect around the number boards but the actual headlights are not very noticeable. There is a black plastic light shield in the body that completely blocked that LED from illuminating the rear lights so I removed that. I think simply adding light pipes for the headlights, leaving the "ambient light" from the LED's for the number boards, and painting the interior of the body black to reduce the glow will work well.

    So, if you have an MTL frame that clamps the board from the sides you will have to completely separate the chassis to install it! Cheers!
     

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