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Oxford Dean Goods + MX645 + SuperCap + 2 Speakers + Firebox glow


Harlequin
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  • RMweb Gold

I decided to have a go at fitting an ambitious DCC rig to one of my Oxford Dean Goods locos to try to get better sound than any of my previous installations. (Except the Dapol GWR railcar, which sounds great using an off-the-shelf YouChoos installation.)

 

At the time of writing I have not been entirely successful (the firebox LED doesn't work) but I'm sure it will work in the end. More on this later...

 

The equipment came from YouChoos and I more or less followed their "more difficult" hard-wired installation guide but with some variations. Parts list:

  • Zimo MX645 with Collett Goods sound project
  • Zimo 6800uF super cap
  • Pre-wired orange firebox glow surface mount LED
  • LS26X20X8 8Ohm speaker
  • Another small 8Ohm speaker I had lying around (sorry for lack of info about this one but see photos below)

The loco is a later revision Oxford Dean Goods, with correct cab sides, etc. in plain inter-war goods green. A proper workhorse that I expect will make regular appearances on future layouts.

 

I describe this installation as "ambitious" because both the loco and tender are relatively small and the devices added to the loco need extra wiring to cross between between loco and tender. (And this is the first time I've attempted anything like this...)

 

The big speaker, super cap and decoder are shoehorned into the tender and there's room for the small speaker in the smokebox. This second speaker will move the apparent sound source out of the tender and towards the cab. The two 8Ohm speakers can be wired in parallel because the MX645 can handle 4Ohm impedance.

 

As you probably know, the firebox LED should operate in sync with the coal shovelling sounds, adding a nice extra touch of realism to the model. Because it is a surface mount device it is quite slim and there's just enough room to fix it in the moulding with wiring running between the moulding and the chassis.

 

Step by step photos to follow (otherwise this will be one huge post!)

Edited by Harlequin
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  • RMweb Gold

Here's the loco body with the smaller speaker mounted in the smokebox:

post-32492-0-24125700-1546192882_thumb.jpg

 

I wrapped kapton tape around the back of the speaker because it is quite close to the motor's extended drive shaft. I think it would be possible to cut the drive shaft short to install a fatter speaker/enclosure but I didn't want to risk that this time.

 

Note that the extended drive shaft carries a second flywheel in the earlier revisions of the model. I don't know if that flywheel would prevent the installation of the smokebox speaker in those models.

 

The speaker is semi-permanently tacked in place using black tack on the sides.

 

I drilled a hole through the firebox doors to mount the LED and very carefully opened it out with knives and files.

post-32492-0-37395400-1546193362_thumb.jpg

 

You can see that there is already a rebate behind the firebox doors but it's not very deep and I thought it prudent to improve the clearance behind the LED by pushing it right through the moulding. The plan is to paint it black so that it's inconspicuous when not lit but hopefully would shine through the paint enough when lit.

 

The violet speaker wires are left overlong at this stage and tacked in place inside the top of the loco body - there's enough clearance between the body and the motor.

Edited by Harlequin
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  • RMweb Gold

As per the YouChoos guide, I removed the DCC socket from the tender and ground down the mounting posts to give a simpler, more open volume to pack the gubbins in. (Also removed the plastic speaker holder, of course.)

 

post-32492-0-67125600-1546194048_thumb.jpg

 

The pickup wires from the loco (via the socket) and from the tender (through the hole in the centre of the chassis) are soldered together and the motor wires (from the socket) are left unattached - that's a simple way to remember which is which. And the other thing to remember is: Red is Right and Black is Left.

 

The next job was to pop out the coal load and remove lots of plastic from the tender body:

post-32492-0-19825000-1546194414_thumb.jpg

 

This is where I started to do things differently from the YouChoos method because I removed much more of the interior moulding than they suggest. I did that because I wanted to arrange the components slightly differently so that I had access to the decoder connections while the loco and tender are connected and standing upright. This will be important when pulling the extra wires for the smokebox speaker and firebox LED through into the tender. The coal load will then simply push back on top to hide the decoder and its wiring.

 

I cut out the unwanted material using a small cutter bit in a Dremel at the lowest possible speed to prevent the plastic from melting during cutting. I was very careful to prevent the bit from jumping and accidentally cutting visible parts of the model! This job created a huge amount of plastic "sawdust" and scurf that had to be gently hoovered away initially but a lot was left clinging to the tender body through static attraction. The simple solution to that was to thoroughly rinse the body under the cold tap!

 

This is the proposed arrangement of the decoder, speaker and super cap in the tender:

post-32492-0-80984000-1546195325_thumb.jpg

Edited by Harlequin
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  • RMweb Gold

I'll fill out more of the details later but in the meantime here's a summary of the current state:

 

I have bodged up the extra connections between loco and tender and... It works! :-) Apart from the firebox LED :-(

 

From a normal distance sound is not obviously coming from the tender alone and when I put my ear to the smokebox I can hear that speaker working. When I toot the whistle the sound is rich, strong and resonant!

 

I can't wait to get it running properly BUT the non-functioning firebox LED means I've got to take it all apart again... Ho hum...

 

 

Edit: I will try to reverse the sense of the LED connections before I do anything else because maybe the pre-soldered wires were the wrong way round.

Edited by Harlequin
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  • RMweb Gold

The next job was to glue the firebox LED in place, package its resistor within the loco body and route the wires out of the loco towards the tender.

 

post-32492-0-50543500-1546247054_thumb.jpg

 

I used rubberised superglue to hold the LED in place but it was very fiddly and unfortunately the result was that the LED ended up a bit skewiff. This misalignment is less visible from the outside and didn't seem to interfere with the chassis so I'm prepared to put up with it for now.

 

The resistor was soldered directly to the LED and the stiff wire holds it in position against the side of the firebox where it will clear the chassis. Then the original blue wire from the LED was soldered to the other end of the resistor and the complete assembly wrapped in heatshrink sleeve.

 

Kapton tape stuck behind the LED to ensure no shorting with the chassis.

 

 

I then carefully remove some material from the cab floor and the rear of the footplate casting to make room for the wires - possibly not enough:

post-32492-0-77292400-1546247622_thumb.jpg

This will route the new wires out in the same slot that holds the model's original wires.

 

I wrangled them into place to ensure that they didn't cross and were as flat as possible, holding them with tiny amounts of black tack:

post-32492-0-92927300-1546248052_thumb.jpg

 

Finally, I fitted the chassis back in the body with lots of gentle cajoling and the occasional swear word:

post-32492-0-61537800-1546248118_thumb.jpg

I will colour the wires black later if they are visibly annoying. (Notice that the blue wire did manage to cross over the others, somehow. Very annoying and that might be why the LED doesn't work...)

Edited by Harlequin
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  • RMweb Gold

Next stage: Wire up the decoder, connect the loco and tender and check whether it works!

 

post-32492-0-89663000-1546248840_thumb.jpg

It looks like an event in the Large Hadron Collider!

 

The tender body is on. The decoder is not yet seated (and I may need to remove some more material from the tender body to get it to fit under the coal load) but I have soldered the pickup wires and the motor feed wires to the decoder tails and protected them with heatshrink.

 

I've also temporarily hooked up the new wires from the loco LED and speaker without cutting them to length or routing them under the tender properly.

 

 

As I said above, this was the moment where I found that it nearly works: no shorts, the decoder was alive and making sounds and both speakers were working. BUT the firebox LED was not working...

 

post-32492-0-83573600-1546249518_thumb.jpg

A quick check showed that the LED output AUX3/FA1 was generating the expected signal in sync with the coal shovelling sound so the problem lies somewhere in the wiring in the loco.

 

At this point I was a bit fed up so I started writing this thread while I work up the enthusiasm to take the loco apart again.

 

It's a miracle that the external details have remained undamaged throughout all this!

Edited by Harlequin
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I found the problem with the firebox LED. it was a bad solder joint. I blame the small bit I was using which has become oxidised and doesn't work very well. 

post-32492-0-81567300-1546283493_thumb.jpg

 

I changed back to my larger bit, re-soldered the joint, applied new heatshrink and pushed everything back into place. Before going any further I tested the LED with a 9V battery - it worked!

 

While I had the body and chassis separated again I painted the surface of the chassis under the boiler Indian Red so that it's the right colour between the frames even though there's no valve gear modelled.

post-32492-0-72561800-1546284469_thumb.jpg

 

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Turning back to the tender I milled away some of the casting just ahead of the socket so that I could thread the new wires from the loco up inside the tender body:

post-32492-0-45955900-1546284750_thumb.jpgpost-32492-0-68569100-1546284775_thumb.jpg

 

Next the tender and loco were reconnected and the new wiring fed through the new gap next to the socket:

post-32492-0-75968000-1546284931_thumb.jpg

 

With the wires cut to length and connected to the decoder which was seated inside the tender body it was time for another test:

post-32492-0-30667400-1546285094_thumb.jpg

 

Success!

 

I just need to insulate the soldered joints, tuck the wires away and refit the coal load.

 

 

Happy New Year everyone!

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The final stages of the installation were very simple. I made sure that the drawbar supports the wires to make them less visible and protect them from dragging.

 

I protected the soldered wire joints in the tender with heatshrink and gently curled the wires down into place:

post-32492-0-17032900-1546347672_thumb.jpg

 

And then re-fitted the coal load and put some of the loose details back on:

post-32492-0-35743000-1546347995_thumb.jpg

 

It's almost as if nothing had ever happened to her!

 

For the record, the small speaker in the smokebox is a 15*11mm SugarCube with a sticky gasket and no enclosure.

 

Things that I could have done differently and may yet do:

  • Use a speaker with an enclosure in the smokebox to get more volume and better sound reproduction from the front of the loco.
  • Use silicone coated wires between loco and tender for flexibility and longer life.
  • Ensure the super cap clears the middle wheels of the tender with something more solid than black tack.

 

All in all, this was a good upgrade and it's fun to drive her using YouChoos' "ImmersiveDrive" feature. I'll post a video when I can.

 

P.S. Apologies for the annoying cat hairs in many of the close-up photos!

Edited by Harlequin
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Here are a couple of very basic videos - I'm not au fait with video editing.

 

 

 

I spent a lot of time trying to sync the chuffs with the wheel rotation and that was about the best I could do.

 

I apologise for the focus hunting in the videos - I'm not fully in control of my technology!

Edited by Harlequin
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  • RMweb Gold

Thanks Grahame.

 

Yes, for various reasons I acquired more than I really need and when I come to run them on a proper layout I'll have to think about their liveries. (And the brass domed version has some questionable features, of course.)

 

The others ended up in shot because I had been comparing how they ran with the upgraded 2475. She has a tight spot in her motion that I don't understand yet - nothing seems to be fouling or rubbing anywhere.

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  • 3 weeks later...
  • 4 months later...

Phil—did you ever get the motion on the 2475 worked out? I have one I just got that is the same way and also has a nasty high frequency motor whine so I hope to convince Oxford to replace the motor. One possible option is to pull the gears, clean off all the oil and grease, then lube it with toothpaste. This was commonly done here in the US back 30 years ago to smooth the rough edges off the gears and get them to run smoother. Once it has been run in with the toothpaste lube, you disassemble it and clean off the toothpaste and replace with oil or grease. I haven't tried this yet as I am waiting to see what Oxford Rail decides to do about this loco.

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  • 2 months later...
  • 8 months later...

Excellent write up, thank you.....I was tempted by the Locomotion Dean Goods at a good deal....complete with massive wooden box! And you have given me some confidence to actually plan to add sound (I am really a dirty diesel man), also as you have already pointed out I reckon you could get away with much smaller gauge wire and if it’s silicon covered even better.

when you actually look at the gauge of the wire used on the decoders straight from the factory I think most of us use wire that’s like a drainpipe compared to the scale of the original wire, just a bit difficult sourcing really good thin wire.

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