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Jim Banner, 27 July 1999
This was not an easy engine to add both sound and digital command control
to, but it was possible. Before starting, Scott and I reviewed George Schreyer's
Digital
Command Control Tips and his Bachmann
Climax Tips in detail, then consulted the tables in his Tractive
Effort Tests to help determine a suitable decoder. I also studied Ross
Webster's DCC
INSTALLATION IN THE BACHMANN CLIMAX and his Climax
Modification to Pick-ups . While we did not follow them exactly, these
articles were an excellent place to start.
The owner of the engine, Scott Gibb, had already purchased a Sierra
sound card and had a spare MRC AD320 decoder on hand. He wanted to operate
this engine on his garden railroad which is equipped with an MRC Command
2000 system complete with a 10 Amp booster. The decoder appeared to be
a reasonable choice - the current draw of the Climax is similar to that
of an Aristo-Craft RS-3 which our group has operated successfully for two
years with one of these decoders.
But first, something definitely had to be done about power pickup. The
wheel pickups in the Climax are fine but the pickups which transfer power
from the trucks to the body are too light. These pickups work fine to transfer
perhaps an amp from the trucks to the body for lighting and smoke generation.
They fail quickly, however, when a truck-to-truck short occurs, such as
derailing at a switch or accidentally straddling a power control gap in
the rails. Scott's failed about five minutes out of the box, collapsing
a spring and distorting the plastic around the pickup, when he tested his
engine using a 10 amp DCC booster running in dc mode.
George Schreyer's
solution is probably the best as by drilling through the "motor block
piece" and adding new wires all the way to the ash pan, he avoids having
wires that can move back and forth right next to a soldered joint, a sure
source of trouble. Ross Webster's solution is easier, but leaves
unsupported
solder joints that may fail. Being Canadians, Scott and I compromised.
We used Ross's solution, but added more wire to absorb the motion. At the
rear truck, we wrapped the wires four turns around a 3/16" rod and tucked
the resulting helix between the motor block piece and the floor of the
tender. At the front, we ran the wires under the boiler in a longish hairpin
arrangement. Unlike Ross, we soldered the wires to the ends of the semicircular
plates at the same ends as the original wires.
While the trucks were apart, we lengthened the motor wires, unsoldering
them from the clips and extending them with 24 ga. Teflon insulated wires
and insulating the joints with shrink tubing. We momentarily connected
the motor leads to a power supply to determine polarity, switching leads
until the truck ran forward. Then we used orange wire for the positive
lead, grey wire for the negative lead. We removed the wires from the original
chuff switches and used one to pull the motor wires from the front truck
through to the tender. (Later we used the other to pull the reed switch
wires from the ash pan to the tender.) Being Teflon insulated, the wires
slipped through easily.
 Photo 1
Next came the power supply for the Sierra sound system. SoundTraxx
recommends using a series resistor for voltages greater than 12 volts,
but there was no one resistance which would be suitable over the entire
output range of the Command 2000 booster. Therefore we decided to use a
regulated power supply, based on a 7812 regulator. We mounted the regulator
on the underside of the coal load by drilling and tapping a hole in the
load. We used an insulator kit (mica washer and shoulder washer) plus some
heat sink compound to keep the coal from becoming electrically hot while
keeping the regulator from becoming thermally hot. In photo 1, the 7812
is at 2, the board supporting the bridge rectifier and fuse recommended
by SoundTraxx is at 3, and the filter capacitor is at 1. Hidden under the
masking tape seen above the power supply board in Photo 1 are the wires
to a miniature toggle switch mounted in the water filler hatch.
 figure
1
 Photo 2
Next we mounted the speaker and sound board following the instructions
from SoundTraxx. Photo 2 shows the speaker mounted on two cardboard gaskets
and the sound board prepared for mounting by the addition of two strips
of SuperLock Fasteners to the back of the board behind the terminal strips.
This allows the board to be mounted on the back wall of the tender with
the push buttons accessible, yet the board can be easily removed. A bit
of gentle prying with a tiny screwdriver inserted between the layers of
SuperLock helps the joints to start splitting. A strip of SuperLock is
seen at 1 in Photo 2. At 2 is a remote volume control switch, a single
pole, double throw, center-off miniature toggle switch which is spring
loaded to center in both directions. With this switch, all sound board
programming can be done without having to open the tender.
 Photo 3
With the sound board in place, we mounted the AD320 decoder under the
top of the tender using double sided foam tape. We filled the area between
the four diodes with several layers of foam in order to give as large a
mounting area as possible. In photo 3:
1 is the 7812 regulator
2 is the power supply board
3 is DCC decoder
4 is the sound board
5 is the power supply filter capacitor
6 is the volume control switch
7 is the loud speaker
We identified which of the two black conductors went to the right-hand
wheels and marked it "red". Then we connected up the decoder and sound
board as follows:
decoder wire
colour |
sound board
terminal |
function |
other connection |
| red |
n/c |
right-hand
wheels |
power supply,
lights & smoke |
| black |
n/c |
left-hand
wheels |
power supply,
lights & smoke |
| orange |
7 |
motors
+ |
- |
| grey |
8 |
motors
- |
- |
white +
yellow |
13 |
bell
control |
- |
| violet |
14 |
whistle
control |
- |
| blue |
n/c |
- |
- |
| green |
n/c |
- |
- |
| - |
15 |
hiss
n/c |
- |
| - |
16 |
coupler
n/c |
- |
| - |
9 |
speaker |
- |
| - |
10 |
speaker |
- |
| - |
11 |
chuff
switch |
- |
| - |
12 |
chuff
switch |
- |
| - |
micro plug
red wire
|
+11.3 from
power supply |
- |
| - |
micro plug
black wire |
- return of
power supply |
- |
Because the MRC Command 2000 supports only two on-off functions, the
lights in the Climax were left as originally connected. With DCC, this
means they are on all the time. This frees up a channel to allow Scott
to turn the bell on by turning the lights function on and to turn the bell
off by turning the lights function off. He can also manually trigger the
crossing whistle sequence by turning the auxiliary function on then off.
This seemed a better choice than having the bell ringing every time the
engine ran slow and having the whistle blow a crossing sequence every time
the engine sped up. Scott has a coupler clank switch on order, so it will
be installed at a later date.
We mounted the chuff reed switch according to the SoundTraxx directions,
gluing it tight against the ashpan cover. The alnico magnets supplied with
this switch were very much stronger than ceramic magnets so distance from
magnet to switch was not an issue, but minimising the risk of snagging
the switch and breaking it, was.
 Photo 4
We managed to hide the on-off switch for the power supply in the water
filler hatch and still have the hatch cover fit. We cut a circle of 1/16"
styrene to be a tight fit in the filler tube and drilled an under sized
hole through the center. Screwing the switch into the hole threaded it.
There is no nut on top, but there is one under the styrene to help keep
the switch from tipping when the toggle is thrown. In order to reinstall
the hatch cover, we trimmed the inner cylinder of the cover flush with
the outer one and trimmed the toggle to leave only 1/8" beyond the threaded
mounting bushing. The switch body fits completely inside the tube with
only the wires projecting into the inside of the tender.
 figure
2 photo 5
We were fast running out of room and another board was out of the question,
so we built the filter free form using compact 50 volt ceramic capacitors
and 1/4 watt resistors . Photo 5 shows the filter sitting on a dime, just
before it was encapsulated in shrink tubing. With the filter installed,
both the sound system and DCC decoder worked as originally expected, with
one exception - the engine gives two toots when starting forward, but it
also gives two toots when starting backwards. At the moment, the cause
of this is unknown, but it is something that we can live with.
 Photo 6
With the tender reinstalled, the only visual give-away is the remote
volume control switch toggle hanging below a corner of the tender. To our
eyes, it looks like the engineer has added an extension to the tank drain
valve to keep the sludge from splashing on his overalls. A piece of shrink
tubing would make it look more like a piece of rubber hose stuck on the
valve, but on this engine, all the engineer could lay his hands on was
a piece of galvanized water pipe. At least that's our story, and we're
sticking to it.
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