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Throttle Network Wiring

SUGGESTION: Sanely Working With Modular Phone Cables

Consider this choice carefully. As Digitrax points out, terminating on screws is cheaper than RJ12 connectors. They also tell you that terminating on screws could potentially be a rat's nest. They are right on all accounts.

RJ12 CAN be very reliable — IF ASSEMBLED CORRECTLY! Be sure the cable jacket is inserted into the clear body of the connector. This is the only strain relief those frail wires will receive. If you fail to do this, the connector will invariably get you into trouble.

If you don't trust yourself to put them together properly, and you want to use the RJ style connector, buy them assembled.

The more I work with the wires coming out of an RJ style cable, the more I hate them. Working with the individual wires borders on impossible!

At the very least, buy RJ cables that have lugs already attached. Even these easily break - right where the wire enters the lug. Be SURE that after you are through attaching the lugs to terminals, you clamp the cable jacket to your benchwork so there is NO stress on the wires where they attach to the lugs. I do mean none! This is especially important if your layout is not in a constantly climate controlled room where corrosion could weaken the wire. They will break!

That's the general info.  Now here is how I prefer to use them.

Ideally this cable should be used with modular connectors on both ends.  AMP  makes an inexpensive tool that does a good job of crimping connectors onto the cable.

In the case of switch machine control, I need individual wires at one end.  I buy a modular jack that already has wires coming out the back of it.  They come with lugs, tinned, whatever suits your particular need.  In the case of my turnouts, I get the tinned ends.  I then Walther's Goo the modular jack to my switch machine.

SUGGESTION (D): Greenish or Reddish Track Status Light?

If the track status light is lit, but not orange, DCC information is being corrupted. Train operation may be erratic. See section on Booster Wiring. SUGGESTION #3-3(D): Conserving Battery Power Between Operating Sessions.

You are going to like this one so much you might think this should be a recommendation!

AJ from Digitrax says, "Short the middle four wires of LocoNet together. This will force LocoNet and the attached throttles into idle; a low power state."

He also suggests that you use a short RJ cable to do this and attach a red tag to it. Or paint the RJ cable red. Just plug it into a throttle jack at the end of an operating session. Don't forget to remove it before you begin your next operating session or nothing will work!

What do you do with the outer two wires? Just cut them off.

You will need to leave something on to keep idle power on the network. Your throttle will draw power from whatever you left on instead of the batteries.  You will be able to leave the battery in the throttle without running it down.  What you leave on depends on what system you have.

If you have a Chief set, leave the Chief DCS100 on. All other boosters may be turned off.

If you have an LA-2: Leave the LA-2 wall transformer on. You may turn ALL boosters off.  The LA-2 will keep the command station throttle powered up.  Note:  The LA-2 requires a power connector with a 2mm barrel.  The center of the barrel must be "+".

If you have an LA-1 & it is powered by the booster it is attached to: Leave that booster on. You may turn off all other boosters.

Will this harm anything? No. And you need not worry about having everything on while this special cord is plugged into LocoNet. It is A Oookay.

Do I have to do this shorting thing? Probably. For example, each BT2 draws 15mA when operating. This may be too much for many wall transformers when you have more than a few throttles. In idle, it draws 100-200uA — considerably less! Even the smallest wall transformer could keep many BT2's in idle.

AJ's right, this is easier than rigging up a switch. Still, some of us, like myself would rather use a switch. Part of the motivation for a switch would be turn off all the boosters at the same time. So a relay or two may be needed. I'll include a schematic on how this could be done 'one of these days.' In the mean time, follow AJ's suggestion.

SUGGESTION #3-5(D):  Don't Torque Down the Nuts Under the Throttle Knobs.

The optical encoders in the Digitrax throttles are soldered firmly to the circuit board.  The circuit board is held in place by spacers.  If you tightened the nuts on the throttle knobs, the nuts will put tension on the encoder while it fights with the circuit board and its spacers.  The solder pins on the encoders may break off.

The nuts should only be tightened just enough so that the nut doesn't spin free and interfere with the throttle knob.  You would probably be okay to do away with the nuts.

SUGGESTION #3-6:  Divide and Conquer a Short in Your Throttle Bus

Track Wiring #5-21 has a good discussion on localizing a short.  If you used phone connectors to make your throttle bus, you can just disconnect them rather than cut the wires.

NCE ProCab Throttle Holder by Don Vollrath

Here is my version of a simple NCE ProCab holder. It is easy to cut out from a 1/4 or 3/8 inch piece of plywood. Round off the corners and finish with sanding filler, varnish or paint. I provided two screw holes to mount it under the layout sub-roadbed surface. The holder keeps operators from laying the throttle down on the layout.

NCE Procab holder


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