upgrading sound decoder on K4

[Mike C]

 I'm slowly upgrading the Sound Value decoders to Econami decoders . I re-did one in the 2-8-4 last weekend , and in the process came up with a possible idea . The stock decoder plugs into the bottom board in the tender . In Spookshows write-up , http://spookshow.net/loco/bachk4.html he shows the wireing diagram for the pins on the board . My idea is to find the female end of these pins and solder them on to the Econami so it could be just plugged in .  I'm also thinking it may work for the 2-8-4 .  Where can I get the little plug ends , and has anyone else already done this ?

[Mike C]

 I think what I want are JST female connectors . The kind where I can solder my own wire to them . Probably the smallest ones they would make . I just need confirmation that they would work , and maybe a part # .

[Mike C]

 More info . Looks like I need a 9 pin socket with an .05 pitch . Has to be short though as it will be mounted vertically in the tender .  Individual female pins will also work , and may be easier to use .

[peteski]

Digikey has thousands of connectors.  But they won't work.  All the ones which have a suitable size utilize  round machined female socket. Bachmann uses square pins.  Square pins are too large to fit into the round receptacles.

I did find some with square sockets but they look to be way too tall to work in this application.
http://www.digikey.com/product-detail/en/5-104192-2/A115239-ND/2259676

[Mike C]

 I'll find out more tomorrow , but I think header sockets may work also .

[peteski]

I'll find out more tomorrow , but I think header sockets may work also .

As long you find one with square shaped sockets (not the round ones).

[woodone]

If we are talking about the male 90 Degree 6 pin connector that is attached to the Bachmann light board. The NEM 651 6 pin socket will fit over the square pins, I have done that more than once. 

[Mike C]

I did buy a new soldering iron , so the plan B ( C /D /E ) is to solder the decoder wires direct to the male pins on the bottom tender board . I think if I bend alternate pins slightly that will give me enough room to solder .  But I'm hoping to be able to try one of the 50 pin headers that Litchfield Station sells as it does have the correct pin spacing .

[RBrodzinsky]

The Sullins 0.05" header sockets on digikey fit (have rectangular holes) http://www.digikey.com/product-search/en?keywords=s9008E-10-nd

[peteski]

Perfect!  I somehow missed that one!

[Mike C]

And so did my supposed expert ...LOL    I have someone sending me a header from Litcfield Station , going to try that one first .

[peteski]

And so did my supposed expert ...LOL

To be fair, Digikey has so many parts (tens of thousands) that even with their advanced search engine, things can be missed.

[Mike C]

 Update !  Received the 50 pin header  from Litchfield Station today ( Thank You Woodone ! ) and it is a perfect , but tight , fit . Now I just need a decoder and a little time . 

[peteski]

Nice! Thanks for the update/

[Mike C]

  Well it took me long enough !  Finally got the correct decoder yesterday , had to send the first one back totally wrong one .  Anyway I made up the new plug from the 50 pin header from Litchfield Station . I bent the pins so it would hopefully fit under the tender shell.



Unfortunately it was still too tall , so on to plan B ..... I trimmed the pins on the bottom tender board down just a bit and tinned them up .



Now for the fun part . Using the pin guide from spookswow.net site  ( the pins are also labeled on the tender board ) I soldered the decoder directly to the pins .



I didn't use a cap , but I set the wires up so one can be added later . ( might be above my pay grade , the decoder is a tight fit as it is ) .  I used a small piece of shrink tubing on every other pin to keep things separated .

I'm much happier with this decoder , although it took me a while to get the BEMF settings right . The loco ran real well with the stock decoder , but switching tho the Econami revealed a bind in the drive train . But after tweaking it for a while it now runs better than before .

The plug idea may work better on the 2-8-4 tender as the decoder is oriented differently in it . Bachmann uses the same decoder in both models ( I checked , the decoders interchange ) so this should give an alternative to those that don't wish to totally gut their tenders and mess with resistors .