Modifying a Lenz LH100 to use a coiled cord

Posted December 10th, 2006 by bikerraypa

The Lenz LH100 is one of the best DCC throttles on the market. This easy mod makes it even better.

Well, I finally got around to a project that I'd been wanting to tackle for a
long time - installing a jack on my Lenz LH100 throttle to enable use of a coiled cord. I got the idea from a picture on the Lenz Digital Plus group at Yahoo, so I figured I'd just tear open my throttle and see what I could figure out. It was actually pretty easy.

After you install the jack, you can use the Lenz LY006 coil-cord, or you can
build your own cord. If you choose to build your own, I've included the parts and tools needed in the list below.

--------------------------------------------------

LIST OF MATERIALS

For Throttle:

Lenz LH100 throttle (duh!)

6P/4C RJ-11 Molex modular jack Mouser 538-15-43-7564

Iron City Premium Lager

.015" silver-bearing solder Radio Shack 64-035

thick (gap-filling) CA glue

For Cord:

6P/4C Clear Kobiconn Modular Phone Connectors Mouser 154-UL6234

DIN 5-pin black Kobiconn DIN plugs Mouser 171-0275

4-conductor black 7" coil cord Digikey H0742C-ND

---------------------

LIST OF TOOLS

For Throttle:

wire cutter/stripper

soldering iron w/fine tip

Beer mug

Xacto knife

straightened paper clip to apply CA glue

For Cord, you will also need:

6P RJ-11 crimping tool

--------------------------------------------------

Let's get started...

First step is to roll the cord up with a twist-tie so it doesn't flop around too much. Then, using a T8 Torx bit, remove the four Torx screws from the back of the throttle.

Carefully lift the gray back section off the throttle. I was pleasantly surprised to see that there really aren't that many guts inside the thing.

I was also pleasantly surprised to see that the soldered connections inside the throttle are already marked with the XpressNET connection to which they associate (L, M, A, B)

The next step is to determine which pins on our modular jack correspond to the
XpressNET connections. First, plug your coil cord into the jack and check the
plug against the pins with a continuity tester. I found the pins to correspond
this way:

Then, bend the ends of the pins 90 degrees so that they are parallel to the jack rather than perpendicular (so it will fit in the throttle casing later).

Here are the pin associations in the DIN plug (the middle pin isn't used):

And the associations in the 6P/4C connector:

Snip off the cord retention pins in the front half of the throttle, and cut the stumps flush with an Xacto knife.

Then do the same on the back half of the throttle.

Nip the studs off the side of the jack...

...and then Dremel the "ledge" on which the studs were mounted until it is flush with the rest of the jack. Clean up the Dremel fuzz with an Xacto, then use canned air to blow any dust from the jack.

Place the jack in the back half of the throttle, centered over the hole through which the original cord protruded. Use an Xacto to mark the inside of the throttle body along the sides of the jack (the jack itself, not the mounting lip).

Score between these two lines at the point where the bottom of the throttle body meets the back, giving you three sides of a square. You'll end up with something like this...

Then CAREFULLY score and snap. Score it really deep before you snap. The plastic is quite brittle. Clean up and square the opening with the Xacto.

Test fit the jack as shown, and remove more material as needed.

place the two throttle halves together, and score the front half of the throttle to complete the "square."

Then snap, score and clean it up.

Time to test fit....and it works! Hurrah!!

Strip about 1/8" from each of the XpressNET leads in the throttle and tin them
with solder. Tin the pins on the jack as well, then solder 'em up and keep 'em
separated (I used pieces of stripped insulation from 16AWG wire).

Carefully apply a few drops of CA to the lip on the jack, and attach it to the
throttle's front as shown (only put glue on the part of the lip that touches the front half of the throttle). Hold it in place until it dries rather than using a CA accelerator.