ESU Decoder in Bachmann Doodlebug...

Sumner Sep 26, 2021

  1. Sumner

    Sumner TrainBoard Member

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    I'm trying to model roughly UP in the late 40's to early 70's but once I saw a UP painted Doodlebug I was bitten. Not sure if any were still active in my time period but I'll make it work in my make-believe world.

    On researching them I found out that they were produced by Bachmann during the infamous 'white gear' years. These gears are noted for breaking and a number of the ones I found on eBay would say something like 'runs but makes a noise'. I sent a message to the seller of the UP Doodlebug I found and asked about how it ran and if there were any obvious noises. The report came back 'no' so I bought it.

    Upon arrival I was a little disappointed in how it ran. Mark at Spookshow actually said that for the time period it was build in that it was a good runner. I struggled to get the shell off but finally succeeded and messed with the motor contacts a little and she started running pretty darn good. Next problem was it struggled to get through my hand-laid turnouts on my small test tracks that has small radius's. It is very light at the passenger end and that was the end that was having problems. With the shell off I added weight but that didn't fix the problem. I then checked the wheel gauge and it was off on all four truck just a bit. I messed with that and it seems to of fixed the problem 95% of the time now. I still have a couple turnouts that it will derail in some times. Other locos don't derail in them so the verdict is out.

    With all of that being said I've fallen in love with watching it circle the test track and run in and out of the spurs I have. I can run DC or DCC on the test track with the flip of a switch but I'm changing all the used older engines I'm buying to DCC thus that now needed to be addressed. At first I thought I was going to have to probably use some of the passenger area for the decoder. I've used a number of $16 to $24 Digitrax (DZ123 & DZ126T) decoders in my installs but I had bought a couple LokPilot Nano Standards last year to also try out.

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    The Nano Standard is smaller and thinner that the Digitrax decoders I'd been using and it looked like I might be able to put it at the top of the frame in the 'baggage' area. The Nano Standard is also a 4 function decoder and I thought I might be able to add some lighting effects with the additional functions, which I hadn't done to this point in my decoder installs. I'd only been using the forward and rear lights. The Doodlebug didn't have a rear light. It had a front light and passenger area light. My plan was to have the headlight, a light in the cab, two lights in the passenger area that could be either bright or dimmed for late night running.

    On another note, after liking the Nano Standard I decided to get a couple more for future installs. I found out that although a few distributors have them they have been discontinued (at least what I was told). I ordered instead a couple of the newer LokPilot 5 Micro DCC decoders as shown above. I think I'm going to like these even more. Besides the 2 Aux outputs they also have 2 additional logic outputs. SBS sells a very small converter circuit that you can use to convert the logic outputs into outputs that can power about any LED or probably something else. You can build your own circuit but I thought the $8 for one of Bryan's circuits was more than fair. The newer decoder also has other features not available in the Nano Standard and it is also cheaper, not much more than I was spending on a DZ12T. I'll still use some of the Digitrax decoders in locos that I don't plan on running much but want them to be DCC but I'm seeing why ESU decoders are so popular even though you will have to spend a bit more.

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    Moving on, the plan was to remove the front light, passenger light and the resistors on the PCB and place the decoder where the resistors were since it could sit down into that recess enough that the shell could go back on.

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    It took a bit to figure out how the track power was getting to the PCB board. Left side power (side shown above) comes from the front and rear wheels/trucks on this side. You can see where the pickups are isolated from the frame (bottom left yellow arrow) at the front and rear of the chassis. Power from the two points goes up to the motor contacts (DC) through the two black wires that are pointed out.

    Right side track power is picked up by the wheels/trucks on that side and transferred to the entire frame. When the screw is tightened on the top of the PCB board in the middle far side the power from the frame goes to the pad and a trace on that side of the PCB board.

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    Since the PCB also has the motor contacts on it I decided to keep it and use it for wiring the power input to the decoder and the power from the decoder to the motor. This was simple and proved to work really well. I cut the two traces by the motor contacts. That isolated them.

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    Above you see the side of the decoder that has a couple components that stick up more than the ones on the other side. This side will be placed 'down' in the square hole in the PCB resulting in more clearance shell clearance above the decoder. The black input decoder wire will connect to the two track pickup wires at the bottom and the red input decoder wire will be soldered to the pad at the back of the PCB. The orange and grey decoder wires will go to the solder pads on the motor contacts.

    Except for doing the additional lighting wiring I want to do this is really and easy decoder install using the small ESU decoder. There is no frame milling. I clearance the inside of the shell a bit and might not needed to of done that. The use of the old light board gives one easy places to solder the decoder wires to for track pickup and motor output.

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    After the picture above was taken I cut the black wires where they had been soldered together shorter than shown and put a short piece of shrink wrap on the solder joint. Then tucked them in under the wires coming out of the decoder. All the other solder connects shown above were to available solder pads.

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    Before moving on to the lighting I put the loco on the test track and ran it to make sure the motor wiring and decoder was working. You can see the video ( HERE ) or by clicking on the image above.…....................... to be continued …........................................

    Sumner
     
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  2. BigJake

    BigJake TrainBoard Member

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    Yet another wonderfully documented DCC conversion article from you, Sumner!

    I'm not one to get hung up on whether or not a piece of equipment I like was "appropro" to any era/location my layout may or may not depict...

    Of course, the advent of 1:1 railroads restoring and running equipment from years past helps a lot. "Hey, Big Boy can pull a long string of double-stacked containers just fine, thank you very much!"

    And "modelling" a hypothetical historical/preservation society's equipment roster and trackage/rights goes a long way, too.

    If I like it, it runs on my road! AKA the "Wherever, Whenever & Western" railroad.
     
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  3. Sumner

    Sumner TrainBoard Member

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    Part 2 ….........................

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    The one area where clearance is tight is right above the motor contacts area where there is also a cross-member in the shell.

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    I filed it the best I could and whittled away at the area with an Xacto knife to make it a little easier for the wiring to pass that point.

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    The blue above is the common positive that needs to go to all the LEDs and the other colored wires from the decoder also go to the LEDs and the decoder will turn the circuits on and off.

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    If I can I like to test the LEDs before connecting them to the decoder wires.

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    When 3D printing at times the print is started with what is called a 'raft'. It is a very think 3D printed platform that the rest of the print attaches to. The reason for it is that some prints don't have much initial surface area so don't stick well to the build table on the printer. The raft does and the part sticks well to the raft in most cases. When the print is done you separate the print for the raft and usually throw the raft away. I keep some and in this case cut a section out of a raft and used it to cover the area under the headlight to stop light bleed from it down into the cab area of the loco. In the picture above the headlight LED is on the other side of that piece of raft. You could use any number of things to accomplish the same end result.

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    Next I tackled the two LEDs for the passenger area. I wanted 2 LEDs to make it look a little more like it would we lighting going along above that area. One could make it even more LEDs if they desired and picked the resistors out that would work for how many LEDs they were using.

    I wanted to have two intensities for the lights (LEDs). I did this by having two resistors in the circuit. One of the decoder wires attaches between the two resistors and the other attaches past both of them to the flexible PCB strip. If the decoder activates (grounds) the wire that connects between the resistors the LEDs are brighter since the current flows through only one resistor. If that wire is turned off and the other wire is turned on by the decoder the current then flows through both resistors and the lights dim. I look at the dim mode being there for later in the evening when the lights are dimmed so that passengers can possibly sleep.

    More on how to use the strips and where to find them ( HERE ).

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    After the isolation cuts have been put in the strip where the LEDs or resistors will go the strip is tinned adjacent to the cuts and at the end where a LED will bridge the two contact strips.

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    I really find these strips useful and even though I haven't found a U.S. Source for them they are well worth the effort of having them shipped to the U.S.. For less than $30 I probably have a lifetime supply for decoder install and other projects such as my Turntable Project ( HERE ).The PCB strip above takes care of the passenger area LEDs and wiring but I still needed to take care of ….

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    …. the LEDs in the cab and headlight. Above I'm making that strip. The blue power wire spans both contact strips and there is a cut in both contact strip with a resistor soldered in above it. After the picture was taken the flexible PCB was cut right above the word 'LED' in the first sentence. The red anode wire to the headlight LED was soldered to one side just past one resistor and the red anode to the cab LED was soldered to the other side.

    The black LED wire from the headlight LED was soldered to the white decoder wire and the black LED wire from the cab LED was soldered to the yellow decoder wire.

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    Above we see the wiring to the PCB strip that has the passenger LEDs on it. Also at the bottom a second blue wire has been soldered near the common positive blue decoder wire to take the current to the second PCB strip that has the resistors for the headlight and cab LEDs on it.

    …....................... continued on the next page …........................................

    The above info is also on my site ( HERE ).

    Sumner
     
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  4. Sumner

    Sumner TrainBoard Member

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    Part 3 and conclusion of decoder install.

    The Doodlebug has the Bachmann white gears that tend to crack. These seem to be fine but who knows what the future will hold for them. Randgust has replaced the Bachmann chassis with a Tomytec chassis for one of these that had bad gears. You can find that build ( HERE ). I ordered one of those chassis from Plaza in Japan. The chassis and shipping was very reasonable and I received it in a speedy 12 days. I'd do business with them again.

    Since mine is running well now I'll just hold onto the Tomytec chassis. I did leave all the decoder and LED wiring the stock lengths. So I have a lot of extra length wiring under the shell and it is working fine and fits but I'll shorten it all up if I make the chassis change. Leaving it long though will help if I have to do that.

    In the next photo I've started to program the decoder before putting the shell back on. I'm able to quickly make a decoder change and then check the change.

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    I have the test track wired so that with a single toggle switch it is either DC or DCC. For DCC I use a DCC++EX Command Station running on an Arduino with JMRI running on a $35 Raspberry Pi computer. I can run either the JMRI throttle or a phone throttle. BTW you can have all of that for under $100.I'm using JMRI'S Decoder Pro for most of my programming but did recently buy an ESU Programmer (mainly to use with some sound decoders). I didn't use it to program this decoder but besides the physical ESU Programmer I have the same version running on a computer where I can't connect directly to a decoder but can use the program to program one and see the CV's that are changed on the computer screen.

    For this computer I programmed it by reading the decoder's instruction manual and writing down the CV's I'd need to change for the lighting effects I wanted and was close to having them right. I also used the ESU Programmer program on the computer to see which CV's it changed but didn't use the ESU Programmer connected to the program track.

    To program the decoder I used JMRI's DecoderPro which I have running on the Raspberry Pi and I can program decoders with it on the program track. The program track is a spur off the main on my test track. It is fairly long and can be switched via a toggle switch to be either the program track or a spur off the main.This is really handy as with the toggle switch one way I can program and save the changes to the decoder. Then throwing the toggle switch makes the spur part of the main track wiring where I can use a JMRI or phone throttle and run the engine to checkout the changes. If I still need to make a change I flip the toggle switch and I'm able to make another change using DecoderPro. Using the same track I can make changes to the decoder and check the changes in a matter of seconds without having to physically move the engine. If the programmable spur isn't long enough to check the changes I run the engine out onto the test track's main oval for testing.

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    Above you can see the computer screen in the background running DecoderPro and a JMRI throttle. The Doodlebug is out on the main oval where I can easily observe the changes made to the decoder if I need a longer track length than the programming track provides.

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    Even though you can dim the LED light to some extent with programming I might try a different resistor for the cab light. If I try and dim it past what is shown above through the decoder it starts to flicker. It isn't bad now and actually dimmer than what the photo shows but I'd like to dim it more if possible.

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    I'm pretty happy with the two different intensities that one can switch between for the coach lights.

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    I have two turnouts that the rear (light end) trucks derail on at times. Since other engines don't derail there I think it is the Doodlebug but maybe the hand-laid turnouts are the problem. I did have to re-gauge the trucks as it started with problems on a lot of the turnouts. I have a feeling that if I changed to the Tomytec chassis things might be better. I also have an Atlas scale speed motor that I'd try if I went that route but the engine has pretty good slow speed control as it is.

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    Above is a screen shot of DecoderPro and the changes I made to what is normally the yellow decoder wire for the reverse light. It is now controlled by F4 on the throttle and won't turn on/off with engine direction changes. Also F2 controls the Aux 1 wire (green) and will turn the coach lights to bright. F3 controls the Aux 2 wire (purple) and turns the coach lights to dim (F2 has to be turned off). On the right side the 'Dimmer' boxes have been checked which allows all of the wires to also be controlled by the decoder somewhat in addition to the resistor that is with LED.

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    Above left you can see the slide controls where you have some control over the brightness of each LED. The current limiting resistor you have on each resistor will also effect the brightness.

    On the right is a screen shot of a JMRI throttle that you can use along with a mouse to control the engine. Since I also labeled each function using DecoderPro I see what the function controls not F1, F2, etc on the JMRI throttle and also on my phone throttle connected to JMRI's web throttle running on the Raspberry Pi. I have no idea how other DCC throttles will react (might see the labels maybe only see the function numbers???).

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    Click ( HERE ) or on the picture above for a video of the Doodlebug running.

    This concludes the decoder install. I really like the ESU decoder's size and how versatile it is. I ordered more and will use them in the engines where I want better engine control, more lighting effects and some of the other features they have over some of the decoders I've been using. They are only about $3-$4 more than the Digitrax DZ126T decoders I've used. I'll still use the DZ123's and maybe some of the 126T's in engines I just need to get running under DCC. Most of my engines are older DC engines. The run well, were less expensive and I like them so no regrets there.

    I also have a couple ESU sound decoders to install and after this experience look forward to doing those installs when time permits.

    You can also find the above info on my site ( HERE ),

    Sumner
     
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