The upper circuit board needs to be removed, and this requires disconnecting
the green wire which is soldered where the green wire is shown on this
When you remove the circuit board, the two grain of wheat
light bulbs are free to fall out. The front from one side, the
rear from the other. Keep them safe.
Two shots of the upper circuit board in the Class 47. The top
photo shows the underside, the lower photo shows the soldered tracks.|
The underside has 4 components that will need to be removed, shown above and
below the long slot.
Above the slot - a choke coil of very thin wire
protected on this model in a yellow sleeve. To the right, a capacitor
small, yellow with a green top.
Below the slot - 2 Diodes.
All 4 components each have two ends which are soldered on the top side.
It may be necessary to ease each connection out a little at a time,
alternating between the two - especially the green/yellow capacitor.
None of these components are needed. The capacitor and coil are
used to supress ineterference. The diodes allow the lights to operate
in the direction of travel. Both of these functions will be carried
out by the DCC chip.
Do not de-solder any of the 3 bonze coloured
connectors which stick out on the lower side of the board. These are
for the motor +ve connection and for the two light bulbs.
Take the motor out, releasing the two bearing clips at each end and the
spring motor clips near the motor body (both described on pages relating to
Carefully remove the cap which has a solder tag on it.
Beware the spring and the tiny motor brush. They can remain in place
if the motor can be kept upright, but don't knock it over - those springs
bounce a long way !
Solder a length of thin black wire to the tag - as shown.
Cover the tag with an insulating sleeve. Here I have used some heat
shrink tubing. The idea is to keep this tag from touching the chassis.
A bit of card or tape stuck between the tag and the chassis would do just as
well - until it falls out.|
Replace the motor in the chassis - you will have to feed the wire through
first. Make sure the wire sits as shown, and then replace the axle
bearing clips (see text and photos in the section on refitting the motor).
The wire makes this a little awkward, and I found it easier to slot the
motor into position loosely, ease out one end of the axle and put one axle
bearing clip in place (loosely), and then do the same at the other end.
Finally push the motor home, and ensure the axle bearing clips lock into
position. Make sure the spring clips are properly inserted to
hold the motor. |
Another shot of the motor, the motor earth wire and the green +ve track feed
which comes from the lower circuit board. The existing wire is good
enough, but you may want to replace it. Heed the precautions about
removing the lower battery box before attempting this.|
We can now use the circuit board for attaching the DCC chip. The
position of the White, Red, Yellow, Orange, Black and Grey leads are all
shown on the diagram as small coloured rectangles. The long thin green
and black wires will be fitted later, but these represent the solder
position of the green +12v wire from the lower circuit board and the black -ve
feed from the motor.
Orange is connected to the Motor +ve brush cap by
means of the bronze tag in the middle of one side of the underside of the
Grey is connected to the Motor -ve brush cap by means of the black wire that
you soldered on earlier.
Red is connected to the +12v power pickup (which should be on the right)
of the loco when it is facing forward)
Black is connected to the -ve power pickup (which should be on the left)
The chassis is used for the negative pickup, which comes through the axles.
It arrives at the board by means of the tiny rear securing screw.
White is for the forward running light and is soldered to the strip
connecting to the front bronze tag
Yellow is for the rear running light and is soldered to the strip connected
tot he rear bronze tag.
Here is a very messy first attempt to make sure that everything works.
I didn't make any attempt to tailor the wires to fit neatly at first - in
any case, these would all lie flat under the roof of the Class 47 without
any problem. This being the first DCC chipped 47 loco that I had
worked on, I wanted to make sure that all worked correctly. The chip
is a Lenz Silver Mini + and needs insulating on its underside otherwise the
solder tracks on the circuit board will make contact. A thin piece of
tape over the top helps keep things in place. The blue wire is not
used - it is intended for the common return from the two lights, but as
wired, the lights are 'earthed' to the chassis - which is connected to the -ve
rail. This is perfectly Ok, although the bulbs are slightly dimmer
than if the blue wire could be used. Its not noticeable.
All that remains in this picture is to fit the circuit board, and solder the
green and black wires. See the little notch at the lower left hand end
of the slot ? Thats where the green and black wires need to be routed.|
Look at the lower bobs of solder under the blue wire. You don't want
your soldering to look like that. It has a 'graininess to it, and in
this case is caused by me when I removed the components - heating the solder
and then blowing from the reverse side to clear the solder from the hole !
Here's another shot with everything in place apart from the loco body.
The blue wire needs to be insulated at the end as yet. I have left the
black and green wires too long to allow the top to be moved out of the way
without desoldering - should I ever need to get to the motor.|
Here is a sequence of 5 photos taken from the second Class 47 that I fitted
with DCC. The Lenz chip is quite expensive, but it is thin and tiny
and fits easily inside the roof space. For this experiment, I wanted
to compar the Lenz with a cheaper model - in this case the Gaugemaster 2
function 36-558A. It comes with 6 pins, so it needs a harness to
connect it. The chip and 6 pin socket/harness are much thicker than
the Lenz, and the loco body will not fit on if the chip is put in this
position. I ended up cutting a rectangle out of the circuit board so
that the chip would sit a couple of mm lower, and this just about gave me
the required space. But the body is still a tight fit.|
The wires are cut more or less to length. For this incarnation, I have
used a red wire from the +12v feed from the lower circuit board, and looped
it around to give the freedom to remove the upper circuit board without
de-soldering. Confusing that there are two black leads. One can
be seen emerging near the chip harness and disappears to be soldered on the
square silver patch under the U bend in the red wire - to make contact with
the chassis via the securing screw. The -ve motor feed is the black
wire that is soldered to the silver rectangle patch at the right hand end of
the photo - to connect with the grey wire.|
In cutting the ractangular hole
in the circuit board, I had to destroy the connection for the lead from the
right hand rail +12v (shown as the green lead in the above photos).
Instead, I have soldered this on the other side of the board.
Same thing from the side.|
And again showing the motor and black wire.|
Ready to go. Well, once it has its wheels and body put into place.
The bogies will physically fit at either end, but to retain the polarity of
the chip and for the loco direction to be consistent with other locos on
your layout you need to check that the insulated wheels - ie the wheels with
the pickups - are on the right hand side of the loco. Difficult to see
because on mine, the pickup strips are painted black. This puts the
traction tyres on the rear bogey, but if you or a previous owner have had
the bogies apart, this may not be true.|