DCC 8 Pin Question...

[Geeper]

I have a few Digitrax 8Pin (DH165IP) decoders. I have a DC Proto 2000 "DCC-ready" with a 9Pin socket. Can I use the Digitrax 8Pin in the 9Pin socket. I realize I'll loose a DCC function or two. I'll match up "P1" pin to "P1" socket hole.
Will it run OK on DCC (and DC) using a 8Pin decoder, or will it totally destroy something... and 'toast' all the electronics...?
Has anyone ever put a 8Pin DCC decoder in to a 9Pin socket? 
Thanks for your thoughts...

[trainman203]

There's a Digitraxx io forum you can ask these questions on.

https://groups.io/g/Digitrax-Users

[Len]

All of my P2K locos have 8-pin sockets. So when you say your loco has a 9-pin socket, is what you're describing something like this?


If so, someone unplugged a previously installed decoder from the JST plug and left the wiring harness in place. You should be able to unplug the harness from the loco's 8-pin socket and plug your decoder directly into the loco's socket.

Len

[Geeper]

Hi Len; Good question, I'll look next time I remove the shell. The Paperwork that came with the loco says DCC-Ready then has directions for both 8pin and 9pin.
If it has 9pin like in your photo (with 9th wire free), and its set into an 8pin socket (like your pic)... its then OK (green-light) to remove and put a DH165IP 8Pin decoder straight into the socket without fear of damage to the loco???
Thanks for your thoughts...
PS: what's the 9th Black wire for...? The 8Pin itself is wired to standards, with P1 being the Orange wire. 

[Len]

Since standards have been set, the 9th wire should be violet. It was sometimes brown before the NMRA standardized the colors. According to Standard 9.1.1, it's used as 'Output 4 (Aux 2)' for decoders that support it.

And yes, if the harness is plugged into an 8-pin socket you can unplug it and install an 8-pin decoder. Be aware that on some, not all, P2K locos there is not enough room between the socket and shell to plug a decoder directly into the socket. So you would use something like a DH126D or DH166PS that comes with a harness like the one in the pic of my earlier post, allowing the decoder itself to be placed in a location that allows the shell to be installed without interferance.

Len

[Geeper]

Hi Len: Thanks for that info... I do have a DH166PS in my DCC parts bin. Also your pic of 8Pin to 9Pin interface woke up my brain... so I built a 8Pin-9Pin interface table. You're right I can just insert an 8Pin and its plug and play, I only loose the violet Function.
I tried to attach tables, but topic 'upload' cashe is full... sorry.

[jward]

Not sure of the exact configuration of your loco, but some do have a 9 pin interface hard wired to the circuit board. Certain Model Power and Mantua locomotives are like this. In this case, it is easy to unplug the wiring harness from the digitrax decoder, and plug the decoder directly into the 9 pin interface in the loco itself. Save the Digitrax harness for future projects. You never know when it will come in handy.

[Geeper]

Hi JWard; Yep, just checked and my DH166PS has a separate 'male' 9Pin to plug into a 9Pin socket. Should work OK. Either way, I have both the 'male' 8Pin and 9Pin. Time to get out my I-Fix-It tiny tools and get this U28B on the rails... 

[Ralph S]

So do you leave the violet/purple wire open.  That is, not connected. 

[Geeper]

Hi Ralph; According to NMRA stnd that 9th violet (sometimes brown) wire is for a fourth function. Many folks just snip it off and only use 3 functions in no-sound DCC use.