# Decoder install



## adaboy (Apr 24, 2014)

I'm getting ready to install a decoder in a loco. Do I need to totally isolate the motor frame as well as the brushes?


----------



## DonR (Oct 18, 2012)

Yes.

The motor must be totally isolated from any contact with
the frame. The wires from the decoder will attach to
whatever input your motor has. You might also make
sure that your lights are also isolated so that the wires
from the decoder are their only power source.

I just converted a Bachmann GP30 that was designed
to have NO WIRES. All current was conducted through
the chassis. The cast metal chassis was split in two
isolated halves. I kept that concept but had to totally
isolate the motor and light board which were designed
to take power from the chassis.

After you do the DCC hookup, but sure to do a short
test BEFORE powering it up. Recheck all of your
wiring. You could blow a brand
new decoder.

Don


----------



## Mark R. (Jan 26, 2013)

As long as the brushes are completely dependent from the frame / case, then you don't have to worry about insulating the motor case itself. 

Many can motors have two separate terminals for attaching the power wires to, yet the case may be screwed solidly to a metal angle bracket such as in many brass engines. In these cases, the motor case does not have to be insulated from the chassis as the two separate brush connection points are not grounded to the case.

It's usually just the older open frame motors that had one brush grounded to the case of the motor. Most all can motors have separate brush contacts for each brush that are in no way connected to the motor case.

Mark.


----------



## Cycleops (Dec 6, 2014)

Most N gauge locos have a split and isolated power system. Be sure to isolate the board components from the frame using Kapton tape if your loco has this system.


----------



## adaboy (Apr 24, 2014)

Thank you for all the info. I'll check continuity between the brushes and frame before I do anything. If not a very high resistance I'll make sure to isolate the entire motor.


----------

