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Class 37 TTS


pd91223

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Does anyone have experience of fitting an R8102 TTS Decoder (8-pin, of course) in to a Bachmann Class 37 (32-781B, 21-pin DCC Ready)? Specifically, will it fit when piggy-backed on a 21-to-8 pin Adapter (DCC Concepts AD218.6 or Gaugemaster DCC72)?

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Having looked at various articles, I'm not inclined to try this now, because I don't want to "hack" my loco around. It's a shame that Hornby haven't considered a 21-pin version of the TTS decoders to fit other manufacturers' locos. Surely it wouldn't be a big re-design job, just a different connector on one end. Would there be a big enough market?

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If the TTS decoders had been based on the sApphire instead of the R8249 then the 21-8 pin conversion would have been simple, just unplug the harness, but it isn’t so we are stuck with the 8-pin decoder and using a separate adaptor.

 

A 21-pin version would be larger and more of a struggle to find space for.

Rob

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@pd91223..........I have opened my Bach class 37 to check, it is already fitted with a Loksound decoder & speaker as you can see........having measured there is definitely no room for the adapter plus the 8 pin plug........

/media/tinymce_upload/19e87f10c4d28d6330e2e05f3d1d5025.JPG

an alternative is to to fit a TCS 21 pin breakout board to which you solder the 8 pin wires off the TTS but you may have to get a UK TCS agent to order it from USA...........

/media/tinymce_upload/b7979fdfa883d26bf86619bc1ef3bb33.png

or.........for about £80 fit a Soundtrax Econami diesel 21 pin sound decoder plus speaker...........HB

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It may or may not help but I have fitted a Hornby Class 47 TTS Decoder, to my Bachmann Class 47, using a DCC Concepts AD218.63, 21 pin to 8 pin adaptor.  This fitted without any problems. 

 

As WilliamDavid says above, there are no modifications to the actual Loco, the only change is a simple plugging / unplugging.

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I am 100% confident that the piggy backing of the 8 pin Class 47 TTS Decoder flying lead onto the 21 pin to 8 pin adapter, fits without problem in my Bachmann Class 37.  The only slight problem I encountered was the speaker because it fouled on the Class 37 Roof Fan.  This would be easily overcome by extending the speaker wires to fit it somewhere else, or relocating the TTS decoder.

 

2 things to note: 

1)  I was trying a Class 47 decoder and I don't know if they are the same as a Class 37 but as long as it is on a flying lead it will be fine.

2) My Class 37 is model 32-780 (Coal Sector)

 

The pictures show the overall view with the TTS Decoder plugged in and a side view showing the height of the piggy backed connectors.

 

/media/tinymce_upload/85c0aff58233783039292acd311c3ef4.JPG

/media/tinymce_upload/9ff13e722f9a3dd84935c7b2e5d2845d.JPG

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@RDS ..... many many thanks for that. Your Class 37 is ten years older than mine, so I'll open up mine and compare with your pictures. The pictures of the Class 37 & 47 TTS decoders look identical - presumably just what's in the sound chip is different - unless it's just a generic image. I don't solder - yet - so if the loco insides seem reasonably similar I'm only worried about the issue with the placement of the speaker. Many thanks again.

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@pd91223, You are lucky, I have not had chance to refit it yet!

The measurements of the AD218-63 are 17.6mm x 15.8mm x 3.95mm (but the 8 pin socket soldered pins protrude out from the bottom, so call it 5mm thick in total).  It's a bit difficult to measure but I estimate that the overall thickness with the TTS Decoder 8 pin Flying Lead inserted, is slightly under 8mm.

 

Let us know how you get on.

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@pd91223..........I have opened my Bach class 37 to check, it is already fitted with a Loksound decoder & speaker as you can see........having measured there is definitely no room for the adapter plus the 8 pin plug........

/media/tinymce_upload/19e87f10c4d28d6330e2e05f3d1d5025.JPG

an alternative is to to fit a TCS 21 pin breakout board to which you solder the 8 pin wires off the TTS but you may have to get a UK TCS agent to order it from USA...........

/media/tinymce_upload/b7979fdfa883d26bf86619bc1ef3bb33.png

or.........for about £80 fit a Soundtrax Econami diesel 21 pin sound decoder plus speaker...........HB

You can get a cheap one on ebay

https://www.ebay.co.uk/itm/DCC-MTC-21-pin-male-to-21-wire-adaptor-PCB-New-UK-Stock-Seller/192672103969?hash=item2cdc26fe21:g:294AAOSwUmtbF70I:rk:11:pf:0

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@sultan..........that's not the adapter required for what we are discussing........the one I have specified is a female socket to plug onto the 21 pins on the loco circuit board then the wiring from an 8 pin decoder can be soldered thereon........your suggestion is a male 21 pin board which is used to plug into a 21 pin decoder so that it can be hard wired to a non-DCC ready loco........HB

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I’m a bit late to this but I have used 21 pin adaptors to fit TTS decoders into bachmann class 37’s, 47’s 66’s and a Hornby 21 pin class 31. They non of them had to be modified, for just plugged the adaptor in and plugged it in. In all cases I cut the speaker off and fitted something of a suitable size but better quality. The class 47 has the least space, the others have plenty of room.

Richard

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/media/tinymce_upload/1c3b861861a1be86a2553775aa615b88.jpg@sultan..........that's not the adapter required for what we are discussing........the one I have specified is a female socket to plug onto the 21 pins on the loco circuit board then the wiring from an 8 pin decoder can be soldered thereon........your suggestion is a male 21 pin board which is used to plug into a 21 pin decoder so that it can be hard wired to a non-DCC ready loco........HB

Erm!    Cut the plug off the 8 pin decoder and solder the wires to the relevant solder tabs on the 21 pin adaptor - simples!

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@richard_croft

I wish I'd had your response before buying the bits. They've arrived and I've fitted them and they're working ... except that the body won't fit back on because of the size/shape of the speaker! I don't solder, so cutting off the speaker and fitting an alternative is not an option!. So, it's probably in the bin with the decoder & adapter 😢

Paul

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@Chrissaf

Many thanks and I will study your tutorial - I had a soldering kit for Xmas but so far have been "afraid" to use it! 😳

 

An update though on the topic first. I thought I had managed to fit the TTS decoder & speaker in the Class 37. It was a very, very tight fit - perhaps too tight, read on. The major problem hindering the fit is the fan assemby attached to the body roof. I do not really want to remove the fan, but I thought I had found a position for both decoder & speaker that might do. Putting back the screws was a challenge, especially those around the fuel tank. I was worried that if the screws were not done up fully then the light connections would not meet correctly. I had to squeeze a bit to ensure the screws around the fuel tank were reasonably tight.

 

So, loco on track, lights on, sound on, forward motion. Then I noticed that the lights seemed to be flickering a bit. One circuit, stopped loco, started it again, loco moved forward but stopped of its own accord, lights changed to opposite direction, flickered and died! Now, dead. Tomorrow I'll take it apart again, but I just hope that by squeezing it all in I haven't "fried" the decoder!! 😢 If, I haven't, then I'll be avidly reading Chris' tutorial, although I still don't see how the decoder can fit even with a smaller speaker without removing the fan assembly.

Paul

 

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@pd91223

I always find it useful to try out a new Decoder installation on the track, before re-fitting the body.  Unless your 10 year newer Class 37 is a lot different to mine, I was sure that a TTS could be made to fit.

 

However, if the speaker remains a problem, those 'sugar cube' speakers (of the correct impedance) are usually quite compact.

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@pd91223...........looking at the 2nd photo provided by RDS on the previous page it would be advisable to insulate the underside of the adapter plate to avoid any metal parts coming in contact with the circuit board when all is squashed down when the body is refitted.........HB

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