No N Gauge layout seems to be complete unless it has a Farish 08 trundling around somewhere, going about its shunting duties! However, with DCC
Sound being added to so many of the other larger locos, the 08 seems odd as the only silent mover, so it is crying out for sound itself!
This is no small challenge though, as you can imagine by the tiny dimensions we are dealing with. Below are a few different approaches to
achieve the dream, including one that is fairly simple using a CT micro speaker, and another using a modified standard CT sugar-cube speaker, both in the
cab. Both solutions take advantage of a CT SL76 decoder, located in different places. The final example uses a Zimo MX649 and Minnow speaker, which is
the recommended approach now.
The choice of which method to go for will be down to your sense of adventure and your pursuit of volume, as the standard sugar-cube speaker will
provide masses of volume compared to the micro cube, and the Minnow decent output without making the install too tricky.
First, let's see the easier solution, which requires very little modification to the loco and places the micro speaker in the cab... (photos
kindly provided from an install done by Richard Simmonds), CT SL76 with MicroCube speaker
Note how the inside of the loco's body has been milled down a little with a Dremel to create just enough space for the SL76 to sit flush above
the motor. A tiny bit has also been ground off the top of the motor and mount to make it flat. The decoder is then protected and stuck to the top of the
motor with trimmed wires connecting for pickups and motor. Connections are quite simple, with the only tricky bit being the isolation of the front
pickup from the motor terminal - bend the pickup tab away from the little circuit board on the front, soldering your decoder pickup and covering with a
small piece of heat shrink to prevent it connecting with the motor connection.
The CT micro cube speaker can be slotted straight into the cab area, trimming the speaker wires appropriately as you go. Secure in place somehow,
perhaps using some thick double-sided tape or Black Tack, ensuring that all electrical connections are safe.
The second solution really goes for it, with a reduced height enclosure on the standard CT sugar-cube speaker - photos kindly provided of a
masterpiece of an install by Carol Harmond aka 'WhiteSwan' (Compiled by Caz, copyright reserved 2012). In this example, the SL76 has been mounted diagonally with some minor mods to the
chassis itself, and (not shown) a small 16v/100uF capacitor (for stay-alive) is squeezed in at the front of the loco. This install is very tight, and not for
the faint-hearted, but the result is stunning!
(Text below also Compiled by Caz, copyright reserved 2012).
First job is to disassemble the body from the chassis by removing the 4 very small screws on the underside of
the chassis, hidden in the four corners. Once the body is clear of the chassis, you can slide the cab part of the
body away from the main body shell, it's difficult to start but does slide off.
To modify the body you have to remove the cab detail area and some of the floor to make enough room for the
decoder. Remove as much as you dare but leave enough metal for the cab fitting track and the four screw mounting holes.
I started with thinning out the floor of the cab, I used a very fine craft saw to cut out the section as shown below.
Once you've finished removing material, it should end up looking something like this:
To give you some idea of how the decoder fits, here's a dummy decoder in situ.
Next to modify is the gear box cover, it is only held on with one screw and just pulls off upwards. This needs the
corner removing to enable the decoder to lie at an angle and another slot needs to be cut on the top for the extra wires
between the front of the loco and the motor.
You will also need to modify the chassis at the back, near where the black wire is attached, this requires a small
chamfer to allow the decoder to sit a little lower so the upper-most end of the decoder doesn't foul against the body.
It is plastic, so a small sharp knife can be used to cut away what's needed. Also paint any exposed metal where you've
modified the body, this will help insulate the decoder from shorts.
You will also have to remove all the glazing from inside the cab otherwise the speaker won't fit. Easily pops out
with a little pressure from the outside on the panes, if they've been a bit slap happy with the glue, you may need to
use a sharp knife to leaver them out from the inside.
That's all the modifactions done, now to fitting the decoder and speaker...
You will need to remove the existing black wire from the tag at the back of the loco and from the motor. Note where
this wire is as you will need to solder the black wire of the decoder to the tag at the back of the loco (track power)
and the grey decoder wire to where it was on the motor housing terminal pad.
With the wires upper-most, locate the decoder against the chassis, I used double sided adhesive tape on the back
of the decoder but didn't actually remove one side of the backing paper, only sticking it to the decoder as an insulator.
Cut the decoder black wire to length and solder it to the tag at the back of the loco now as this will be covered by the
decoder. Once soldered in position, place a small piece of insulating tape over the exposed tag to help insulate from the
decoder. Also put a small strip of insulating tape at the bottom of the decoder where it touches the chassis to insulate
it from the body housing.
The other track power pick up needs to be isolated, I did this by inserting a piece of card between the tag and the
terminal on the back of the motor housing, I also bent it slightly to one side, see below.
Solder the red wire of the decoder to the insulated tag (track power pick up), the grey wire to where the original
black wire was attached to the motor and finally solder the orange wire of the decoder to the terminal on the motor
board that the tag used to make contact with. See the above picture. Just to re-cap, track power pickup, black and
red wire is via the two tags, motor power, grey and orange wires soldered direct to the motor terminal pad.
Lay the wires that go to the front of the loco in the grooves of the gearbox housing (I've left the light feed
wires intact as I hope to fit some lighting) but ensure if you do this that they are all well insulated at the free
ends or you'll blow the decoder.
Carefully replace the body ensuring all the wires at the front are in the nose area and thread the rest of the
wires through where the cab control panel used to be, including the brown speaker wires. I've left the speaker wires
temporarly long for testing purposes. It doesn't matter which brown wire goes to which speaker tag, there is only one
speaker so you don't have to worry about phase errors.
You will now need to modify the cube speaker and the speaker sound box housing. You only need to cut the smallest
corner off of the cube speaker and the housing so that the speaker goes right into the roof area. You will also need
to reduce the depth of the clear plastic sound chamber by about 50% so that it is much thinner in profile. I did this
using a razor saw. You have to use the sound chamber or you won't get the volume of sound needed.
Once you're happy that it all works, (shorten the speaker wires if you've left them long for testing purposes)
then put the speaker and housing onto the back of the loco. Again make sure if you have loose wires that they are
well insulated. As you can see, it's a very tight fit but it does all go in if you've made enough room. I had to
retrim some of the cab area again to make a little more room for the decoder and speaker,
it's a matter of trial and error.
Carefully replace the cab sliding it down its grooves, ensuring you don't trap any wires and the speaker
is vertical. Job done!
Our next example uses a Zimo MX649, which is the preferred decoder nowadays, as the Zimo performs much better than the CT. The decoder is
hard-wired and mounted toward the back of the loco, into the roof of the cab. Some filing is required of the gear-box housing and cab
interior. A Minnow speaker fits just about perfectly with a little fettling in the cab (some off the floor and the glazing removed.
Our example here shows a Minnow6, but you might want
to settle for a Minnow4 or Minnow5 to make the install a little easier.
Photos courtesy of Jeanette Harris
Our final 08 takes the above example one more step by adding a small stay-alive. You are unlikely to completely cure all slow-speed stalls in
this little model, but the addition of the SACC16 board and a single 330uF Tantalum makes a big improvement.
Remove the body, and carefully slide the plastic cab up away from the metal body.
Remove the motor mousing and grind as much as you are comfortable to do. We kept going until the outline of the frame started to appear!
Grind off the entire cab detailing from top to bottom, and a chunk out of the cab floor. With hind-sight, we probably would have
taken another mm off the floor area to make fitting the speaker slightly easier later. This is all done with a combination of
a milling machine and hand files.
We have also milled the roof at the back to make it slightly flatter for the decoder to sit as high as possible. The MX649 is too wide
to go through the aperture into the cab space, so the side walls need to be worked thinner too. Keep testing the fit by putting the decoder into
place until it slides in comfortably.
With unwanted wires removed, and Kapton to tape wrapped around, we wire the decoder into the model's pickups and motor, same as
all the other examples. Speaker wires retained too of course. At this point we had no idea that a stay-alive was going to fit, so we don't
yet see the wires for that!
Now we can put the metal body back on and screw it back into place, and start test-fitting the speaker. Here we have used
a Zimo MicroCube speaker with a YouChoos enclousre to make it up to 6mm. 6mm enclosures can be supplied by special request. At this point
we also notice that there is a little extra space at the back of the motor housing, which just might accomodate a cut-down SACC16 board
with a single Tantalum capacitor, so that's what we have. We've gone with a 330uF tall/narrow Tantalum. Lots of test-fitting at this point.
With the SACC16 and Tantalum wrapped in Kapton tape now, we squeeze everyhing gently into place. This is where a little extra depth taken off
the metal cab floor would have been useful, but it just goes in anyway. Ensure that the speaker wires cannot touch the metal of the cab floor.
The clear plastic of the rear window must be filed down a little so that the cab can slide back on, but on it goes, all flush!
Back on the track, and now with sound and stay-alive - marvellous!