How do I hard wire a speaker (to 8 pin HM7k)?

[George-351466]

I have just acquired an Oxford Rail N7 tank loco. A delightful model which runs superbly when DC tested. I expected a bit of a challenge in fitting an HM 7000 8 pin decoder, as usual with a small tank loco. The N7 is, however, the biggest challenge yet. The socket is under the coal bunker and although the decoder fits - just; there’s no external space left for the speaker plug to fit

So, is it possible to solder the speaker wires direct onto the decoder board, and if so, how is it done?

The N7 body is metal, which makes the possibilities of utilising the big cab space difficult and whilst the speaker can be hidden under the rear of the boiler (hidden by the side tanks), the plug-in connection just can’t be used.

The same, of course, applies to fitting the power bank which would have to go into the cab - if it was possible to feed the connections through as well as solve the plug-in problem. Fingers crossed it’ll be OK without the stay-alive, but a speaker is a must.

All thoughts and suggestions gratefully received. Many thanks.

[SteveM6]

Jenny Kirk produced a short video that may give you some guidance. Just be aware that this will invalidate the warranty on the decoder.

[Brew Man]

In view of what Steve says, it might be worth setting your decoder up first with the loco body off and with the speaker plugged in normally to ensure all is working correctly before invalidating the warranty.

[96RAF]

I would suggest soldering to the pads marked SPK…

[Bulleidboy]

I have done this and it worked perfectly. I accidently pulled the speaker socket off of the decoder. Soldering the wires as Rob (96RAF) has indicated worked without any problems. The pads are very small so be very careful when soldering - if you are able to "tin" the pads and the wire beforehand this helps.

Does anyone know what gauge the wire is that is used for the speakers - and can you buy two-colour 2-core twisted wire?

[96RAF]

I have done this and it worked perfectly. I accidently pulled the speaker socket off of the decoder. Soldering the wires as Rob (96RAF) has indicated worked without any problems. The pads are very small so be very careful when soldering - if you are able to "tin" the pads and the wire beforehand this helps.

Does anyone know what gauge the wire is that is used for the speakers - and can you buy two-colour 2-core twisted wire?

 

 

Make your own twisted wire by wizzing it in a drill chuck.

I have found 30 awg wire - super-soft silicone sheathed.

[Bulleidboy]

Thanks Rob.

[96RAF]

I did suss out a Chinese factory supplier for the twisted tails with the correct plug fitted and they worked out at around £2 each if I ordered 100, so I binned that idea. Cost of setting up their machinery I suppose, given ordering 500/1000 really brought the price down proportionately.

[Kim-344602]

The plugs should be readily available. Not very keen on the speakers supplied so ordered some better sounding ones from Roads and Rails. A quick chat before hand and they arrived with the correct size plug already on.

Another option would be to cut the attacked speaker cable and splice a new length in. But that would need two lots of silicone insulation. Or un-solder the wire from the speaker, add the extra length and re-solder to the speaker. One one splice that way. Both options save any possible mishaps with the decoder and a better "new" speaker is quite cheap.

Also a much wider choice of speakers available so you end with a better fit as well as better sound.

[Pendragon Sailing]

The plugs should be readily available. Not very keen on the speakers supplied so ordered some better sounding ones from Roads and Rails. A quick chat before hand and they arrived with the correct size plug already on.

Another option would be to cut the attacked speaker cable and splice a new length in. But that would need two lots of silicone insulation. Or un-solder the wire from the speaker, add the extra length and re-solder to the speaker. One one splice that way. Both options save any possible mishaps with the decoder and a better "new" speaker is quite cheap.

Also a much wider choice of speakers available so you end with a better fit as well as better sound.

 

 

Are you saying that Roads & Rail really supply their speakers pre-fitted with the requisite micro plug for the HMDCC decoder?

[96RAF]

The plugs should be readily available. Not very keen on the speakers supplied so ordered some better sounding ones from Roads and Rails. A quick chat before hand and they arrived with the correct size plug already on.

Another option would be to cut the attacked speaker cable and splice a new length in. But that would need two lots of silicone insulation. Or un-solder the wire from the speaker, add the extra length and re-solder to the speaker. One one splice that way. Both options save any possible mishaps with the decoder and a better "new" speaker is quite cheap.

Also a much wider choice of speakers available so you end with a better fit as well as better sound.

Are you saying that Roads & Rail really supply their speakers pre-fitted with the requisite micro plug for the HMDCC decoder?

 

 

I thought they were 1mm pitch, not 0.8mm as required.

[P-Henny]

The plugs should be readily available.

 

 

Just to add to 96RAFs reply on previous page. The 1.0mm pitch connectors are indeed readily available, but unfortunately these are too big for the Hornby 0.8mm pitch connector sockets. The (non readily) availability of 0.8mm pitch connectors has been previously discussed at length.

See also my reply in this previous thread linked to below for a source of speaker connector and pre-terminated wires to use with the connector.

https://uk.hornby.com/community/forum/hm-dcc-issues-hm7000-8txs-cable-length-and-replacement-speaker-with-plug-362957#post-362998

[Kim-344602]

The plugs should be readily available. Not very keen on the speakers supplied so ordered some better sounding ones from Roads and Rails. A quick chat before hand and they arrived with the correct size plug already on.

Another option would be to cut the attacked speaker cable and splice a new length in. But that would need two lots of silicone insulation. Or un-solder the wire from the speaker, add the extra length and re-solder to the speaker. One one splice that way. Both options save any possible mishaps with the decoder and a better "new" speaker is quite cheap.

Also a much wider choice of speakers available so you end with a better fit as well as better sound.

Are you saying that Roads & Rail really supply their speakers pre-fitted with the requisite micro plug for the HMDCC decoder?

 

 

Yes, if you ask him. He did 10 for me. He really is a very helpful guy.