Pictures and Diagrams

[Yampa Bob]

As mentioned in my opening post, and in response to requests, I am preparing a pictorial for complete disassembly, repair and reassembly of a Spectrum 2-8-0, along with a few modifications for easier servicing and testing. The task requires small metric nut drivers which I have on order, and some time to make up documented pictures.

Meanwhile, for those wishing to hard wire decoders in the tenders, I offer a couple of ideas to make the install neater, with a bonus of being able to use probes for testing.

I cut off all extra nylon to make them small as possible. Strip off about 5/8" of  insulation, twist wires and fold over, tin with solder before inserting into connectors.

Here are micro-sized terminals for a custom PC board, available with 6,7, or 8 connectors.

http://www.ebyelectro.com/terminal-block-product-info.asp?ProductID=85

[pdlethbridge]

I got a bunch of connectors here that are about 1/3 smaller, .1" center spacing.
http://www.futurlec.com/ConnPolHead.shtml

[db22]

I just installed a Bachmann decoder in my DCC ready Decapod. (The Decapod is DOA but that is another thread.) I had some dual in-line headers (DIL) for 16 pin IC's and cut them with cutters to 2 single in-line 4 pin headers. Spacing is correct and they worked fine but the coal lid on the tender would not go on properly. The plug has to be very low profile with the wires coming out of the side for the lid to go on so I trashed the idea and soldered the wires directly to the socket.

[Yampa Bob]

I obtained current versions of the USRA Medium DCC ready tenders. The PC boards appear to be "3rd Release", as used in current models of  DCC equipped Spectrum 2-8-0.

First release PCB is shown in the opening post.
Second release PCB had 2 resistors and 1 diode added.
Third release does not have the resistors or extra diode. 

I tried both Bachmann and Digitrax decoders, with the tenders coupled to my Spectrum 2-8-0. The main difference noted was a smoother startup and more linear throttle response with the Bachmann decoder. I suggest using only Bachmann decoders with these tenders for optimum compatibility.

[Yampa Bob]

Due to a question regarding motor wiring in another thread, I have repeated my reply in this thread as a prelude to the Spectrum 2-8-0 tutorial.



A permanent magnet DC motor has no electrical "polarity", only the magnetic polarity of the internal magnets.  In other words, the motor has no specific positive or negative terminals.  Read on please. 

By convention, shaft rotation on small permanent magnet motors is stated as viewed from the brush end (rear) of the motor, either clockwise (CW) or counterclockwise (CCW) rotation.

The presence of a red dot or plus sign on a new motor simply indicates that the positive lead connected to that terminal produces the rotation as specified by the motor manufacturer or the factory producing a motorized device, typically CW, but may be CCW depending on the maker and the application.
 
The Spectrum 2-8-0 uses direct drive. By that I mean there is no intermediate idler gear.  The worm gear is "right hand", just like a right hand thread on a bolt, and since the motor is positioned with the output shaft to the loco rear, the shaft must rotate CW for forward motion.

If a motor is positioned with the output shaft forward and is direct drive, then the shaft will rotate CCW for forward motion.  (So far I have found no markings of any kind on my Connie motors.)

Bottom line, wire the motor to achieve proper shaft rotation. If loco direction is wrong, then switch the wires. Here is a flash animation everyone should view.

http://www.mabuchi-motor.co.jp/en_US/technic/t_0102.html

Why the confusion?  Using a decoder as an example, the orange wire is labeled "Motor Plus".  The "plus" is not referring to the motor terminal, it means "this is the positive lead, when the controller direction is set to forward motion...... connect it to the motor terminal that results in proper direction"

If you had previously marked a motor terminal as "+" because the orange wire was connected to it, and you had correct direction, then the orange wire would be reconnected to the marked terminal.

You should always confirm proper shaft rotation before re-assembling locomotive.

[Yampa Bob]

This should have been included in an earlier post, but due to visual problems I admit to being a bit disorganized these days.

I found an "Important Notice" packed with one of my Spectrum 2-8-0. The notice has not been included with any of my other Connies. Thinking that others may not have seen the notice, I shall include it here: (quoted exactly from the notice).

IMPORTANT NOTICE

"In accordance with strict international electronic emission regulations, Bachmann locomotives are equipped with suppression capacitors and inductors (RF chokes) to reduce interference with radio and television signals.

NMRA conformant DCC decoders,including Bachmann E-Z Command decoders, will work properly with these capacitors and inductors, but these components may cause a malfunction of decoders that do not conform to NMRA standards.

To prevent damage to locomotives equipped with decoders that do not meet NMRA standards or are not part of Bachmann's E-Z Command line the suppression capacitors and inductors (RF chokes) on this locomotive must be removed from the circuit board before non-NMRA decoders are installed."   (end quote)

For the reasons stated, I now use only genuine Bachmann decoders in Bachmann locomotives. (or Soundtraxx sound decoders, which I have been informed are compatible with Bachmann circuitry).

Tne notice was "Printed in China", so the warning should probably have read: "To prevent damage to (Bachmann) locomotives (by installing decoders) that do not meet......etc".

[Warflight]

THIS topic is a life saver!

Thank you, thank you, thank you!

[Terry Toenges]

Seeing Yampa Bob's name in the post is a blast from the past. He was a wealth of knowledge.

[Warflight]

Yeah, I found this completely by accident, and it answered a LOT of questions I had on DCC, and installing a decoder! I'm looking at a couple of DCC ready engines, and was worried I wouldn't be able to install a decoder, but this thread eased my concerns a bit.

[Molly877]

What type of topics can be posted here, what things we can post in off-topic boards?

[rich1998]

Not needed

[WoundedBear]

Rich......why are you replying to 3+ year old threads?

Sid

[WoundedBear]

What type of topics can be posted here, what things we can post in off-topic boards?

And to answer your question....read this link.

https://www.bachmanntrains.com/home-usa/board/index.php/topic,8493.0.html

Sid

[rich1998]

Oops. I saw it pop up behind Mollys post. It was middle of the night. I was up and bored. I will remove it.  Never noticed the date. I was surprised to see the post by Molly again.

Rich

[Gary Allen]

I guess MMR refers to "Master Model Railroader," a certification obtained via the National Model Railroad Association (NMRA).  Almost as many abbreviations as in the government.  I am curious: do any of you MMR's use digital scopes to troubleshoot these issues or is everything done via a multimeter?