6 pin decoder - common positive for functions?

Post all your DCC only problems, solutions and discoverys here.
Giraffe
Posts: 55
Joined: Fri May 16, 2008 1:31 pm

6 pin decoder - common positive for functions?

Postby Giraffe » Fri Nov 30, 2018 8:15 am

I was considering using a 6 pin decoder in some little tank engines that I will be converting to DCC, but as I am also potentially going to add lamps to them, I might make use of the light functions. What I don't get is where the common positive for the functions is?

On the 8 pin decoders I have, the blue wire is part of the socket, and the fourth function is just a separate wire. But the 6 pin ones I have looked at have no blue wire on the socket, so that makes all light functions unavailable for just plugging the decoder in, so how can you have DCC ready examples? But even aside from that, I can't see on the example I looked at (the DCC Concepts 6 pin nano) that there is a separate blue wire for common positive? (I can see the black and dark blue wires for their stay alive connection).

Am I missing something obvious?

User avatar
Roger (RJ)
Posts: 1381
Joined: Tue May 29, 2007 2:59 pm
Location: Nottingham, UK.

Re: 6 pin decoder - common positive for functions?

Postby Roger (RJ) » Fri Nov 30, 2018 8:27 am

You use one of the power feeds (ie black or red from the wheel pickups) instead of the common positive, or both can be used if you include a couple of diodes to prevent a short circuit.

Mike Parkes
Posts: 627
Joined: Sat Sep 01, 2007 8:25 pm

Re: 6 pin decoder - common positive for functions?

Postby Mike Parkes » Fri Nov 30, 2018 1:36 pm

Diagram on this web page may clarify the matter
https://dccwiki.com/6_Pin_DCC_Plug

Giraffe
Posts: 55
Joined: Fri May 16, 2008 1:31 pm

Re: 6 pin decoder - common positive for functions?

Postby Giraffe » Fri Nov 30, 2018 7:44 pm

Ah, yes thanks that does clarify things. Means that for converting a non-dcc-ready loco, 6 pin is less useful for anything that might want functions, as the space saving of the chip is offset by needing the rectifier :roll: I think I'll stick with 8 pin for these ones. Thanks all!

Suzie
Posts: 287
Joined: Tue Dec 17, 2013 11:46 pm

Re: 6 pin decoder - common positive for functions?

Postby Suzie » Fri Nov 30, 2018 8:21 pm

If you have any MTC-21 blanking plugs you might be able to cut them down and make a 12-pin or 16-pin PluX socket and plug a Zimo MX600p12 in. That should save you a lot of space and you will have access to the blue wire pin on the socket. Will be much smaller than an NEM652 8-pin socket and you won't have to coil up and hide all the decoder wire.

Bramshot
Posts: 205
Joined: Thu Jul 07, 2016 6:55 pm

Re: 6 pin decoder - common positive for functions?

Postby Bramshot » Sat Dec 01, 2018 12:09 pm

If you mean the Zen decoder, I don’t think it has any functions additional to the front and rear lights, which are on the pins.
I used these for the stay alives, but found the stay alive capability is too limited to be of much use and they have the annoying property of setting off at the last speed set, with no acceleration after power is restored following a short, for example. I think this is how they achieve the stay alive effect, the small capacitor serving to hold the memory on the chip alive, so that a brief interruption to power does not result in speed returning to zero, followed by acceleration ramp, but apparent continuation at constant speed.
Other decoder manufacturers, such as Zimo, provide a solder pad for the common positive, ground and numerous other pads for the function outputs on their 6 pin decoders, provided you feel confident enough to solder to them.

Giraffe
Posts: 55
Joined: Fri May 16, 2008 1:31 pm

Re: 6 pin decoder - common positive for functions?

Postby Giraffe » Sat Dec 01, 2018 1:59 pm

Yes, the zen was what I was looking at simply because the 2 decoders I got first were 8 pin Zen 360, so just continued looking at that particular range when working out what the connections would be, as I'm assuming they are standard socket wiring across manufacturers when talking 6 8 or 21 pins, as it's they're all NMRA standard?

I am not aware of anyone on this forum who is particularly an advocate of the DCC Concepts decoders (as opposed to some of the other brands that variously have some fairly vocal proponents! :wink: ) but so far all my issues have been my own stupid fault and the decoders have been fairly robust in the face of me plugging them in wrong, making ridiculous adjustments, accidentally shorting the connections (both trackwards and motorwards of the decoder!) (multiple times!) so I have no complaints about them yet, but also have nothing to compare them against. I will look around some of the other brands for my next decoders as they won't be bought on an Amazon voucher, which really gave me no choice for basic-level decoder other than the Zen range for my first pair.

As I've still got some 8 pin socket boards, I'll probably stick to that rather than the 21-pin idea. I'm happy soldering up some circuits, but slicing up boards is a bit much for me right now! :lol:

Mike Parkes
Posts: 627
Joined: Sat Sep 01, 2007 8:25 pm

Re: 6 pin decoder - common positive for functions?

Postby Mike Parkes » Sun Dec 02, 2018 11:04 am

Why not just hard wire a decoder in place - saves a lot of time and fundamentally in locos with little space a big space saving if you do not have a socket occupying much needed space. Indeed on a number of DCC ready locos I have I have removed the socket so enabling a bigger choice of decoder than would fit the highly restricted space as supplied with the model. My approach to decoder fitting is that it should be part of the chassis - I have a distinct dislike of decoders slotted into bodies with the tricky reassembly that results.


Return to “DCC Forum”

Who is online

Users browsing this forum: No registered users and 4 guests