MU Lashup Wiring Standard

[dnevil]

I've read about MU (multi-unit) lash-up of 1.5 inch scale diesel locomotive.

Is there a standard pinout for cables between model diesels? If not, then what might such a standard look like? Here is a page that describes the cabling for full-sized diesels.

http://www.railway-technical.com/us-musp.shtml

Thanks,
Daris

[ccvstmr]

Daris...it's been a while since I was involved with this kind of stuff on the RR. Yes, Amtrak equipment had a 27pin Pyle National connector car to car for communication and signal circuits and between the loco and train. Believe the locomotive MU controls also used a 27 pin jumper...but something tells me it had a different "key" to prevent the jumpers from being cross connected. Typical of real RR hardware...they were big, heavy and usually difficult to plug in and latch.

On our models...creating a standard WOULD be nice, but with so many companies producing locomotives that could be MU'ed...you'd have to get "buy in" from all builders to standardize not only on the wiring, but also on the connector brand to be used. I've seen connectors for MU and hand control boxes range from something as simply as a computer DB12 or DB25 connector (relatively cheap 12 or 25 pin connectors) up to something really robust like Amphenol military grade connectors.

I would think the bigger problem of creating a standard is that not all locomotive controls would be identical. Not all motors are permanent magnet. There are various types of electronic controllers that need different control signals. The number and type of aux. controls, including brake controls would also span a wide range. IMHO...this is a situation where one size will not fit all.

In my case, I've got a pair of Backyard Rails F7-A units. One unit powered, the other unit a dummy. The locos were originally equipped with a Conxall brand of plastic connector housings with "loose" inserted pins. In time, when the connectors were joined, the pins would get pushed out the back of the connector. I decided to bite the bullet during one electrical upgrade and replace all the connectors with Amphenol 14 pin connectors. Never regretted that decision. The connectors had "cast in" solder pins. No more problems with loose pins. However...you have to understand how to order/spec out Amphenol hardware. Some connectors have about 5 part numbers to make (1) complete male or female connector.

Not sure where you want to go with this. Not trying to rain on your parade. Just pointing out some of the obstacles that need to be overcome. Hope that helps. Carl B.

[Steggy]

DB-15 or DB-25 connectors will work as long as:

2. Maximum current flow is limited to approximately one ampere. These connector types are suitable for control circuits, but not power handling circuits.
   
   
   
3. Both plug and receptacle have cast-in or moulded-in solder cup style pins. If the connector uses crimped-on pins that are inserted into the connector body after crimping they will eventually work loose and fail.
   
   
   
4. Pins and sockets are gold-flashed. The usual "tin-plate" (no relationship to tinplate model railroading) will corrode due to airborne moisture and eventually develop high resistance. Gold-flashed pins and sockets exhibit very low resistance over a long time span.

Connector reliability can be increased by permanently attaching the receptacle to the locomotive or car, rather than letting the mated pair hang free on cables.

[dnevil]

Hey ccvstmr,

Very good input, thanks. I will soon start renovation of a large Boxcab, and also have plans for building a Baldwin VO-1000, so I'm trying to plan ahead, as I'd like to add MU capability to both.

Perhaps the full-size locos could provide a guide for creating an MU standard. Namely, the A B C D lines that are used to indicate the 8 throttle positions. I realize that most LS diesels use continuous controls, but it might be fun to be "limited" to the standard 8 throttle positions.

BTW, could you provide the part numbers for the Mil Spec Amphenol connectors you used? I've been looking at those too, as they look more like the round connectors on the full size, more so than the D-shell DB9/25 connectors.

I'd sure like to hear from any other manufacturers on what they use for MU.

Daris

[dnevil]

Hi BigDumbDinosaur,

Are there any vendors/individuals using DB9/25 connectors for MU? If so, do you have a pinout?

Thanks,
Daris

[ccvstmr]

Daris...I'm on the road right now. If possible, give me a couple weeks to dig up that info. All I can remember is that I used Amphenol 14 pin, molded in connectors having 4 rows of pins in a 3-4-4-3 config. The connectors are physcialy larger than the DB connectors...but you never heard anyone in the military complain about them! Good, tough electrical connectors. We'll be in touch. Carl b.

[Steggy]

Are there any vendors/individuals using DB9/25 connectors for MU? If so, do you have a pinout?

There may be, but I'm not familiar with any of them. I have my own configuration, which uses 24 of the 25 pins in the DB-25 connectors. My system trainlines a lot of the stuff that the real locos would trainline, plus some things that are peculiar to modeling.

Perhaps the full-size locos could provide a guide for creating an MU standard. Namely, the A B C D lines that are used to indicate the 8 throttle positions. I realize that most LS diesels use continuous controls, but it might be fun to be "limited" to the standard 8 throttle positions.

Been there, done that.