Decoder Installation In An
IHC/Mehano 0-8-0 Steam Engine.

Paul Bailey, fellow member of our Nottawasaga Model Railroad Club, likes steam engines. He doesn't run any diesels. Paul has become very proficient at decoder installation in steam locomotives. Recently, he turned up at my weekly operating session with an IHC/Mehano 0-8-0 switcher. As I also have one of these locomotives from a set sold a few years ago by Loblaw's grocery stores under the President's Choice brand, I asked Paul if he would write me up some instructions on how to do it. I have just completed the installation following Paul's directions. Here they are:

Preface

The IHC/Mehano engines, while being sparse in the detail department, are exceptional steam engines in performance. The premier line of steam engines are equipped with large can motors and flywheels making them well worth the effort and expense of installing a decoder. While this article is written based upon decoder installation in an 0-8-0 switcher, it can be used as a guide to install a decoder in a Mikado, Northern, Hudson, or Pacific type engine. I recommend that when selecting a decoder, use a good quality one which has a wiring harness (the decoder plugs into the wiring socket). The plug-in decoder is recommended because if you need to troubleshoot the engine in the future, complete rewiring of the engine will not be necessary. The first engine I ever installed a decoder in is an IHC/Mehano and while I found it challenging, it was not completely out of the realm of most modelers' skills. The first installation should take approximately 5 hours to complete so remember to take breaks or simply set it aside for the day if your patience level is waning. Remember to double check yout work before soldering and this is a hobby so have fun!

My notes are in italics: Paul used an NCE decoder with 4 auxilliary outputs because he had a 4-pack of them. I used a Lenz decoder with a plug. I usually hard-wire my decoders, but this time I also used a plug-in in case I want to install a sound decoder in the future. I'll only have to wire in the speaker's leads.

Tools Required

3mm slot screwdriver
No. 1 Phillips screwdriver
Soldering iron with small tip.
I used a Black and Decker at 30 watts. The tip I had was a little too large.
Flux core solder (and rosin core solder, not acid)

Materials used

NCE 9-pin decoder with harness (D13SRJ).
I used a Lenz LE103XF because I had one sitting in my drawer. Use whatever you want that fits in the tender. There's quite a bit of room. I removed the black sprues that were still in the tender.
Shrink tubing in various colors
Intermountain 33" wheels IRC40050 for tender (optional)
Couplers, your choice
I used a Kadee #5 in the front of the locomotive and a McHenry in the tender, again because I happened to have them on hand.

I found it easier to change the couplers as soon as I had the tender apart and the trucks removed.

Paul did a decoder installation in both an IHC Premier 0-8-0 switcher with a USRA tender and one with an extended tender. He also repainted the locomotives while he was at it.

Procedure

Start by removing the tender shell. The extended tender has no screws, just a tab under the front truck. The USRA tender has a Phillips No. 1 screw under the rear truck. Gently pry back the tab to release the shell. I used a small flat screwdriver to lever the body shell off while prying back the tab with another screw driver. It's easier to get at the tab if you remove the trucks first. Remember which side of the axles are insulated. This will be important later.

Remove trucks. Remember polarity.
The trucks are secured inside the shell
with a hex nut.

Cut all the wires inside the tender and the wires leading to the engine. These wires will not be used during the installation. Leave a little extra wire where the original wire is soldered to the locomotive's rail pickups. I left about an inch to avoid melting the plastic, stripped them, and used some shrink tubing when resoldering leads to these pickup points. The reversing light in the tender will not be removed (unless you are replacing with an LED) so you can leave these wires long.

Remove the trucks from the tender setting aside the hex nuts, truck screws and electrical contact plates.

I used a soft cradle from MicroMark to hold the engine. You can also keep the parts in a tray, empty medicine bottle or parts box. Remove the bell from the locomotive. It is easy to lose it!

*Hex nuts secure the trucks inside the tender shell.*

Then, for this decoder installation, remove the locomotive's shell by loosening the screw in front of the driving wheels. The screw passes through a plastic bushing. Note the orientation for reinstallation. It is a slightly different size than the bushing in the front of the tender.

Remove the screw in front of the
driving wheels.

The wiring harness has color coding. This is the NMRA standard.

a. Red - electrical pickup engine facing forward right side
b. Black - electrical pickup engine facing forward left side
c. Blue - common wire for lighting (front of engine or back of tender)
d. White - locomotive's headlight
e. Yellow - tender's backup light
f. Grey - motor's negative
g. Orange - motor's positive lead

These are the only wires you need for this decoder installation, unless you are installing sound. If so, follow the manufactuer's instructions. Note that the back and red connections are at opposite ends of the harness plug. The orange and grey wires are opposite these. If you are wiring to a new socket, as I was, use the harness as a visual reference. The worst that can happen is the locomotive may run backwards when you want it to go forward.

Routing of wiring in engine.

You can fix this by changing a CV or by switching and resoldering the red and black leads. Take extra care to make sure you don't create solder bridges between the pins. Wrap everything with tape when you're finished to make sure there is so inadvertent touching of metal to metal somewhere.

Paul continued: Strip wires and twist together all new leads. The red, black and blue wires need to be cut close to the decoder plug and a new wires run from the rail pickup points and the motor in the locomotive. I replaced all wires from the locomotive including lengthening the wires from the front bulb. I used black wires for everything because that's what I had. It's easier if you have some colored wire left over from other projects. 22awg size wire is adequate. Paul found he had to enlarge the hole in the tender to accommodate all the wires. I managed to insert them without enlarging the hole. Leave enough slack between the locomotive and the tender so the tender doesn't lift off the rails. I also added a half ounce of weight front and back over the tender's trucks after the installation was done.

Solder all wires. Add wires to the tender's contact plates. Install the trucks so that the "hot" sides face opposite rails. Wire one truck to the black pickup and the other to the red. Be careful that you keep the red side for both locomotive and tender on the right side when the engine is facing forward.

*Group the wires.*

Group all wires from engine to tender and wrap them as a cable as much as possible. You can use elctrical tape. Take care that no wires are interfering with the flywheel. Don't forget the slack.

*Keep some slack in the wire "cable".*

Secure all the wires and wrap the decoder, plug and socket with electrical tape. Some modelers advise not to use electrical tape because it leaves a sticky residue, especially when hot. I've never had a problem.

Decoder installation in tender

The photo above is of Paul's installation. I secured my decoder to the floor of the tender with double-sided carpet tape between the extra half ounce weights I put in to help keep the tender on the rails.

*Everything connected.*

Test your decoder installation on the programming track first to make sure you haven't created a short circuit anywhere. If everything is OK you can key in an address for the engine and then put the locomotive and tender on the main track and give it some power. Does it run in the correct direction? Do the lights work correctly with F0 turned on? Once everything is OK, fine tune your CVs for starting voltage, braking, momentum or whatever other "tweaks" you like and start switching!

Decoder installation completed.
Photos by Paul Bailey

My loco, CN8333, ran in the wrong direction first and the front headlight wouldn't turn on. After I rechecked the wiring and got everything fixed, the locomotive ran fine except the flanges don't like the Code 70 dual gauge trackwork on part of my layout. It looks like the locomotive will be restricted to Underhill North and Fort Eerie where all the track is Code 100 or Code 83.