Thanks guys. Very helpful.
- Harry
HarryHotspur rrinker Simplest is to just get decoders with the 9 pin JST plug on them. This is on the decoder - most of the ones that come that way come with plain wires to hard wire into a loco that has no decoder socket - yet if something should happen, you can pull out the decoder without unsoldering it all. That's the easiest and most straightforward way of having some sort of plug between the decoder and the loco. For truly DCC ready locos, the decoder can have wires that terminate in an 8 pin plug to go into the waiting socket on the loco. --Randy Just to make sure I understand, the 8 pin plug will plug into the 9 pin JST socket, correct?
rrinker Simplest is to just get decoders with the 9 pin JST plug on them. This is on the decoder - most of the ones that come that way come with plain wires to hard wire into a loco that has no decoder socket - yet if something should happen, you can pull out the decoder without unsoldering it all. That's the easiest and most straightforward way of having some sort of plug between the decoder and the loco. For truly DCC ready locos, the decoder can have wires that terminate in an 8 pin plug to go into the waiting socket on the loco. --Randy
Simplest is to just get decoders with the 9 pin JST plug on them. This is on the decoder - most of the ones that come that way come with plain wires to hard wire into a loco that has no decoder socket - yet if something should happen, you can pull out the decoder without unsoldering it all. That's the easiest and most straightforward way of having some sort of plug between the decoder and the loco. For truly DCC ready locos, the decoder can have wires that terminate in an 8 pin plug to go into the waiting socket on the loco.
--Randy
Just to make sure I understand, the 8 pin plug will plug into the 9 pin JST socket, correct?
No, they are two different things. The 8 pin connection is one of the NMRA standard decoder plugs which many 'dcc ready' locos in HO have in them. The way it's wired, you can have a 'dummy plug' to conenct certain pins of it so tha tthe loco runs on DC out of the box. To add a decoder, you remove the 'dummy plug' and plug in the 8 pin conenctor from the decoder. This isn't always just a simple plug in operation, since there's no real standardization of the term "dcc ready". But regardless of other modifications that may be necessary, the decoder connects tot he loco via an 8 pin plug that you can easily remove and swap in another decoder. Decoders witht he 8 pin plug on the end of the wires might have those wires then soldered directly to the decoder. In other words, it disconnects only at 1 end - the end with the 8 pin plug.
However, some of these decoders have an ADDITIONAL plug and socket on the decoder itself. That's the 9 pin JST conenctor, also listed in the NMRA standards and recommended practices. This allows you to disconnect the wires at the decoder end of things. And some locos, like newer Athearns, have this 9 pin plug in the loco already, INSTEAD OF the 8 pin type. And for other locos where th eonly alternative is to solder the wires from the decoder directly to the loco, there are decoders that have the 9 pin plug at the decoder side and then just plain wires which you can cut to length and solder in place.
And thent here are board repalcement decoders - most common for Atlas and Kato locomotives. Those decoders have no plugs of any sort, they are shaped like the DC light boards that come in those types of locos, and have the connections in the same physical spot as the original DC board - so it's pretty obvious where the wires go. You can often install these without soldering anything - there are usually small plastic caps that hold the wires on the DC board and those are reused with a decoder. However, i don't find these reliable and just solder the wires anyway. At that point I'd have to cut or unsolder the wires to remove the decoder.
The best way to prevent damaging a newly installed decoder is to first try it out on the program track. Obviously this requires a DCC system with a dedicated program track. The current on the program track is too low to fry a decoder if it's not installed correctly. So you first try programmign the decoder - if it doesn't respond, you've got something miswired. If it works fine onteh program track you can be fairly confident that you haven't done something silly that will cause the decoder to go up in smoke the minute power is applied.
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Harry:
RRinker is absolutely correct, but let me try to simplify his answer.
Most DCC ready locos today come with either an 8 pin plug or a replacable light board that is plugged into an 8 pin plug.
Many decoders come with a 9 pin plug on the decoder onto which is plugged a removable wire harness.
If the decoder is intended for a DCC ready loco, it will have an 8 pin plug on the other end of that harness, otherwise the other end will just be wire that you must solder. If you use the solder type, you can still unplug the decoder at the 9 pin end of the harness.
If you have the brand and model of your loco available when you order the decoder, the sales person will be able to tell you which decoder and harness you need.
Check this out:
http://digitrax.com/ftp/dh163p.pdf
Dave
Lackawanna Route of the Phoebe Snow
Harry,
The original NMRA DCC spec had an 8 pin(2X4) plug/socket. This was back in the early 90's. Since then the inline 9 pin JST socket has become very popular. One of the problems with the old socket was that it was hard to plug everything and get the shell back on. Many of the new decoders has a JST plug/socket and a bunch of wires that can be hard wired to the wheels/motor/lights. This makes it very easy to swap out a decoder. Some of the vendors provide a cable with a JST on one end and a 8 pin NMRA plug on the other end.
Athearns current 'RTR' engines has a 8 pin socket, with a short cable and a 9 pin JST on the end. You can just remove the 'dummy' plug and plug your JST decoder into it - very nice.
The bottom line is that the 8 pin and 9 pin are not compatible unless you have the short adapter cable. Digitrax has several different 8 pin to 9pin JST cables available.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
installing DCC decoders in older locos? I mean, if a decoder burned out, what would allow for an easy replacement? Do the connectors have a NMRA standard? Does Radio Shack carry them? Any good internet sources?
Sorry for the naive questions, but DCC is new to me.