Peter Witt trolley

In late 2013, Bachmann announced a 1:29 trolley. First units shipped in 2014.

This is an unusual departure for Bachmann, since they have never made a 1:29 model before. Lots of speculation on what this "means". My take is what they said, would be too large in 1:20.3, and would go with the existing Aristo 1:29.

The model is well scaled, but it has some variations from the prototypes, mostly because many different municipalities had these.

 

The G scale trolley seems to be patterened after their existing O scale trolley:

 

This picture is from the Bachmann catalog page on the Los Angeles Railway: http://shop.bachmanntrains.com/index.php?main_page=product_info&cPath=491_493_494&products_id=3179

An interesting feature of many of these trollies was a "safety screen" on the left side of the car, so that when cars passed each other closely people could not hang out the window and hit another car or person. You can see it on this illustration.

DCC operation

Overview

I was curious how to put DCC into this unit. I read in advertising that it had DCC capability.

From the Bachmann web site:

Features include:
• 1:29 scaling
• DCC ready with factory-installed 21-pin and 8-pin sockets for DCC decoder installation of your choice
• can be operated on track power or overhead wire (trolley wheel compatible with LGB overhead wire)
• sound ready with factory-installed speaker
• precision can motor
• LED headlight and rear stop light
• interior lighting
• manually operated front and rear bi-fold doors
• painted interior with seats
• photo-etched brass safety screen per prototype

I looked for information on the 8 and 21 pin sockets and I could not get much data.

I asked on forums about decoders since it came out and got nothing.

Finally almost a year later Stan Ames indicated that the 21 pin socket was indeed an NMRA standard, but the NMRA site did not help (more later).

My question was "offically answered" on the Bachmann forum:

http://www.bachmanntrains.com/home-usa/board/index.php/topic,24132.0.html

Our Just announced 1:29 Scale Peter Witt Streetcar has a standard MTC21 interface that is fully compatible with MTC21 decoders in the market. 
The streetcar has a standard 8 ohm speaker so must be used with decoders that support 8 ohm speakers.  We also include an standard 8 pin socket that includes a solder pin for a second function output.

That still did not give me all the information I needed, because by this time, the streetcar had destroyed a decoder, that DID meet the MTC21 standard.

 

Investigation

OK, there are several things wrong here, the standard, how Bachmann implemented it, etc.

After a year, still no official word from Bachmann on decoders that work, only unofficial information on one that did not, thanks, I could tell by the smoke as the streetcar destroyed the decoder that it did not work!

The Bachmann "socket"

First, as of August 3, 2014, about a year after the announcement and release, there is nothing on the Bachmann site or documentation or on the box, or ANY literature that specifies this loco meets the MTC21 standard.

The response from the "Bach-man" - I assume this is about as official as I will get - is as above, but the MTC21 standard is all over the place.

There is no wiring diagram included.

I did receive a communication from Stan Ames about some of the pins:

Greg

Be glad to help if I can  Note the Zimo D version is not recommended per the Zimo website.  I have no experience with this decoder.

Please note that the following pins have no connection inside the Peter Witt

1,2,3,4,5,6, 17   

When you use a suitable decoder is simply plugs in.

Stan 

Also, the sheet included with the streetcar implies some connections:

 

 

The "standard"

In the quest for the NMRA standard, I encountered issues. A year ago, I believe I found the place on the NMRA site that said basically "this is a weird standard and we don't recommend people use it". Then later I could not find it at all. Now here is what I found: http://www.nmra.org/sites/default/files/standards/sandrp/pdf/S-9.1.1_Connectors_2013.07.pdf

To me, the first thing on the page says volumes:

Under review. Please contact NMRA S&C
Dept. for update. 21MTC and PluX
connectors are being modified and/or
removed.

Continue to read section E on the 21 pin interface:

E: 21 Pin Connector Interface2

and notice footnote 2?

2 Starting Jan. 1st 2010, this connector will not be recommended for new locomotive designs. This will not invalidate the
conformance of existing designs. Controllers for these connectors will continue to conform, as controllers for this connector will
be required as long as locomotives with this connector exist.

Not off to a good start Bachmann.

So, what is the standard?

How about MOROP? The NRM660 standard is here:  http://www.morop.eu/de/normes/nem660_d.pdf

In any case, there seem to be some pins in question.

From my investigation, the picture below matches the "in limbo" NMRA standard

BUT, the Morop standard is not the same:

Pin 3 is aux 6 train bus clock (notice there is no AUX 5)

Pin 4 is aux4 train bus data

pin 17 seems to be a generic type of output

So whose standard does it match?

At this time, the only information is coming from Stan Ames.

 

http://www.bachmanntrains.com/home-usa/dwg/dwgs/LS_Peter_Witt_Streetcar_%28Electronics%29.pdf

 

 

 

 

 

This was still not specifc enough, but I finally got a pdf from the Bachmann site that describes the switches and the "socket":

http://www.bachmanntrains.com/home-usa/dwg/dwgs/LS_Peter_Witt_Streetcar_%28Electronics%29.pdf

From reading the table, the "generic 8 pin decoder with extra function" did not sound like a good idea, so a 21 pin decoder was obtained, and another reason was that I did not find an 8 pin decoder with extra function that had sound also.

Note well, the NMRA considers the 21 pin interface an outdated interface and wants to discontinue it. Apparently this was adopted as a copy of the Morop 600 decoder standard.

I only found a few manufacturers that still make this interface, and Zimo has a trolley sound, and I have a Zimo programmer, so I decided to get one, an MX631

The NMRA standard is defined in this document:

http://www.nmra.org/sites/default/files/standards/sandrp/pdf/S-9.1.1_2012_07.pdf

Note that the standard says that the part in the locomotive is male pins, not a socket. The socket is in the decoder.

Below is a pinout of the pins as you see them in the loco:

 

Note also "motor 3"? This is not use on DC or AC motors. Note also Hall 1-3, used for reading the Hall effect sensors of brushless DC motors.

In any DCC install, the first thing you do is ensure that the motor and track pickups are isolated.


Now, as the streetcar comes, to run on DC there is a "sandwich" of  TWO dummy plugs/adapters installed. This concept allows DC operation, or a 8 pin DCC decoder or a 21 pin DCC decoder, actually pretty clever. (pictures courtesy of an old friend from the NW)

I'm going to start the explanation in sort of "reverse", with a picture of the main board with nothing plugged in. It is a bit hard to see, but the MTC21 "socket" is in actuality 21 pins sticking out of the main board, as it should be:

As you see above, the streetcar is "ready" for a "standard" decoder that follows the MTC21 "standard".


If you are going to run DC or an 8 pin decoder, you need to add one of the adapters supplied. The "first one that goes on is part number "G917x+PCB03", which has the 21 pin socket, and an 8 pin NMRA socket. The picture belows shows the 21 pin socket:

The other side of this board has 4 diodes, 2 resistors and a transistor.

And the picture below shows this adapter installed in the streetcar:

In the picture above you can see that there is now an 8 pin socket. At this point you can install an NMRA 8 pin decoder, or "keep going" to add the rest of the "sandwich" to basically "jumper" the streetcar for DC operation.


Below is a picture of the DC dummy plug. It is a bit hard to see in this picture, but there are 8 (actually 7) pins "sticking out" at the camera. this plug basically connects the track pickups to the motor and the lights to power.

The "sandwich" of the 2 adapter/dummy boards looks like this:

 

But wait, there" more:

 

http://www.bachmanntrains.com/home-usa/board/index.php/topic,28055.0.html