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8 pin to 21 pin adaptor problem, help please!


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I am currently trying to fit a Soundtraxx Econami 21pin sound decoder to a friend's Samhongsa brass k1 4-8-4.

I have purchased an 8 pin to 21 pin adaptor but there seems to be a mismatch between the decoder and adaptor as the "missing pin" on the adaptor plug and the Soundtraxx decoder socket are transposed and the plug will not fully enter the socket.

Please see the attached photos for clarity.

The only way that the plug will fully engage and match the pin holes is by inserting through what I would consider to be the back of the decoder socket as in photo 1.

Is this correct, it just doesn't look or feel right and is fouling the larger yellow box when fully pushed home?

Any thoughts please?

fullsizeoutput_cc9.jpeg

fullsizeoutput_cca.jpeg

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Thanks for the reply, as mentioned in the final part of my original post, to do so doesn't look or feel right, see new photos.

Surely the correct side of the 21 pin decoder socket to plug into is the raised side of the socket?

Certainly this would allow the adaptor board to clear the decoder components.

fullsizeoutput_ccd.jpeg

fullsizeoutput_ccc.jpeg

Edited by Virgil
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It doesn't look very pretty, but that is the right way, it can only fit one way. I make my own short leads to convert 21 to 8 pins, with individual pins, it doesn't matter which side of the female block the pins go in, as long as they go in the right holes.

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Believe me I have tried all placement possibilities and there is only one way that all the pins fit the decoder, you may be able to see this if you study the first photos and that is as shown in my second post.

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11 minutes ago, Virgil said:

The only cabled adaptor that I have been able to find is listed by Strathpepper Junction and they are out of stock.

Make your own. Take a 8 pin blanking plug, file a groove between the pins down the middle of the long length, 3 grooves between the pins across the short side so that all the soldered joins have been cut and you now have 8 separated pins.

These are the straight and angled pins I use to push into the decoder socket. I use 1 set of 5 pins for the motor/track connections, and 1 set cut in half for the 2 speaker wires. That's all I need for my steam locos.

https://www.ebay.co.uk/itm/193845222159

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18 hours ago, daltonparva said:

Make your own. Take a 8 pin blanking plug, file a groove between the pins down the middle of the long length, 3 grooves between the pins across the short side so that all the soldered joins have been cut and you now have 8 separated pins.

These are the straight and angled pins I use to push into the decoder socket. I use 1 set of 5 pins for the motor/track connections, and 1 set cut in half for the 2 speaker wires. That's all I need for my steam locos.

https://www.ebay.co.uk/itm/193845222159

Thanks again, I have ordered from the EBay seller to try, also another adaptor to also try to see what fits best.

I have to fit everything in the loco boiler as the tender floor resolutely refuses to be detached to gain access!

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I used the same (similar) decoder in a Triang DMU(R157?) & is sits at an odd angle mostly due to the large yellow box(capacitor) 

The 21 pin board it's plugged into is a ESU board similar to the LIAS board WIMorrison links to a couple of posts back

 

R157.jpg.866f99d62c56afec35da2b538c3229a9.jpg

 

John

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On 13/01/2021 at 16:52, Virgil said:

I am currently trying to fit a Soundtraxx Econami 21pin sound decoder to a friend's Samhongsa brass k1 4-8-4.

I have purchased an 8 pin to 21 pin adaptor but there seems to be a mismatch between the decoder and adaptor as the "missing pin" on the adaptor plug and the Soundtraxx decoder socket are transposed and the plug will not fully enter the socket.

Please see the attached photos for clarity.

The only way that the plug will fully engage and match the pin holes is by inserting through what I would consider to be the back of the decoder socket as in photo 1.

Is this correct, it just doesn't look or feel right and is fouling the larger yellow box when fully pushed home?

Any thoughts please?

fullsizeoutput_cc9.jpeg

 

The pins cannot be in the wrong place as they are deliberately designed to fit in one position only. You may well have had the same problem fitting the decoder into some locos with a 21MTC interface as I know that some mainland European makes have interfaces that only accept decoders "back-to-front".  Arguably your problem is that the pins on the adapter board are not long enough because of the height of the components on the decoder.

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11 hours ago, John ks said:

I used the same (similar) decoder in a Triang DMU(R157?) & is sits at an odd angle mostly due to the large yellow box(capacitor) 

The 21 pin board it's plugged into is a ESU board similar to the LIAS board WIMorrison links to a couple of posts back

 

R157.jpg.866f99d62c56afec35da2b538c3229a9.jpg

 

John

And it works fine, that's good. As mentioned earlier and due to the tender base not allowing access to the inside I'm having to fit the sound decoder into the loco boiler barrel which is proving problematic when the thickness of the 8 pin socket is also taken into account. It's looking as if a hardwiring job may be necessary from decoder to motor, track and speaker, similar to the example shown in the attached photo.

s-l1600 (1).jpg

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3 hours ago, GoingUnderground said:

The pins cannot be in the wrong place as they are deliberately designed to fit in one position only. You may well have had the same problem fitting the decoder into some locos with a 21MTC interface as I know that some mainland European makes have interfaces that only accept decoders "back-to-front".  Arguably your problem is that the pins on the adapter board are not long enough because of the height of the components on the decoder.

That's right, I also have the added complication of lack of space in the loco if an adaptor board is used as well.

Edited by Virgil
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Yes! 

I just came back to the forum to provide an update and saw your request, thank you.

It's done and working fine and is in the post to my friend, fingers crossed that he's also happy with it as I am.

I went with the Lais DCC breakout board as per WIMorrison's last post and hardwired the leads to the board. It just fitted in the boiler shell above the drive tube and gearbox though only after modification by cutting off the overlapping part of the breakout board with the 3 mounting screw holes. This allowed clearance for the can motor, all very tight. The sugar cube speaker fitted in between the boiler reinforcement bulkhead and the smokebox weight.

I was surprised at the sound quality of the Soundtraxx board and especially the speaker, though minimised the rod clank sound on drifting/coasting, as it made it sound like an ill maintained WD 2-8-0!

I ordered and received your suggested pins and will keep for possible future use, thanks for the suggestion.

I'm now about to ask more questions as I'm doing a sound conversion on a Bachmann 2-6-4 tank which is not doing what it should do! {:O(

 

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