Doodlebug

[graywolf]

Does anyone have experience in converting a Doodlebug to DCC? I expect to use a Digitrax sound decoder # **136 ** don't remember  the letters. Thanks

[RAM]

The one I have is a plug and go.

[graywolf]

I see the 8 pin plug socket, but did you plug a decoder in it and still were you able to close up the shell?  There is a note that came with the engine to cut the green wire if installing a decoder. The picture shows a jumper wire running diagonally across 2 pins on the 8 pin plug, but on my DB there is nothing there --the holes are empty. What decoder did you use?

[graywolf]

Another question maybe someone can help me. I bought some LED lights on a self adhesive strip to use on the ceiling of the passenger section. They say they operate on 12v so I hooked them up a MRC 1370 power pack on the DC side. I have 6 LED's on the strip and started increasing the speed control. At around 7v output at the 1370 the lights were on fairly bright. I tried to lower the brightness by putting a 670 ohm resistor in the line. The lights were still bright and the voltage after the resistor was 5.8v. I then put two 465 ohm resistors in series in the circuit without the 670 ohm and the lights were still bright and the voltage still read 5.8v I thought the resistors were supposed to reduce the voltage    and thus the brightness. What am I missing besides sleep?

[jonathan]

Understand that I am a novice in things electrical.

Here's my guess:

Connecting identical resistors in series probably doesn't produce the desired effect because the second resistor has nothing left to resist.  Imagine two water valves on the same pipe.  If the first valve is tightened halfway, the water flow is reduced by half.  Even when the second valve is turned halfway down, if will have no effect because the water is already flowing into the second valve at half flow (pressure).

A single, larger resistor will most likely give you the dimness you seek... say a 1K ohm resistor.

Another thought:  the tape-up LEDs you have may contain an element, like a small capacitor and resistor, designed to provide the programmed current flow, no matter how much voltage is already flowing into the circuit. 

Those are two wild guesses, but that's how I would approach the problem.

Regards,

Jonathan

[Gearedenginefreak]

Those resistor values, although helping to protect the leds, are pretyy low to try to dim anything.  Many folks will use a 2k ohm or even 3k ohm for a single led for a headlight.  Those leds dont take much to be extremely bright. And it takes a surprisingly large resistor to be able to get any significant dimming..

Good luck,
Tom

[graywolf]

Jon, I am learning also and just found out that resistors in series are additive. I will try adding more and see what happens.

[graywolf]

Well I got the Bug powered up with a Digitrax SDXN136PS decoder and it responds very well. I managed to run it around the 3 loops of my layout and it negotiated all the switches very well. The problem I am having is that it has a noticeable thump sound and a slight jump up on the front wheel area. Any thoughts from the group?

[ebtnut]

Hate to say this, but that sounds like a split gear.  If it is still under warranty you may have to send it to Bachmann.  Don't know if installing DCC voids the warranty. 

[rich1998]

The two inductors are Ferrite 4.7 micro Henry inductors often confused as resistors. No resistance. I measured them at least ten or more years ago with an LRC meter.
Just looking at the stripes you can tell they are not resistors.

Rich

[graywolf]

Can anyone offer some insight as to how you open up the gearbox so I can inspect the gearing? Thanks

[rich1998]

Here is a diagram. I see a split gearbox. Are you mechanically inclined? Layout all parts carefully. I have done a split chassis o-6-0.

https://www.bachmanntrains.com/home-usa/dwg/dwgs/HODoodlebug_Chassis.pdf

Rich

[graywolf]

Thanks Rich, are the parts just friction fit together so that you just pull them apart or pry them? Do you think the damaged gear is obvious to the naked eye? I have to see if NWSL has the parts necessary and to what extent they come as an assembly.

[rich1998]

By the look of the fasteners I would expect Phillips head screws. I see what looks like tiny fasteners. Click on the Plus sign the PDF. All the joy of model railroading I have found out over the years.
I am a retired machine mechanic also. I have come across mysteries many times.

Rich

[graywolf]

Managed to get the gearbox open. Just a matter of pulling on the bottom cover by using the journal and spring area of the truck as a handle. Plenty of grease in there but one of the spur gears on the wheelset was cracked. Possibly the other is also but it looks like a seam in the casting of the gear. I had to unsolder the pickup wires since there wasn't any slack. Be calling NWSL to see if I can get replacements. Haven't tried yet but are the wheels just pressed onto the axles? Also I see a plastic bushing in one of the wheels on a set ---does it matter which side it is on the assembled truck?