DCC Concept 6 pin decoder

[ColinB]

I have nothing to do with DCC Concepts, but I wanted to share a good experience I had with them. I converted an old Mainline 0-6-0 to DCC, not a very difficult job just take out the motor screws retap for 2mm thread and put in nylon screws. I initially, went for a LaisDCC decoder, and with the body off, it worked perfectly, then put the body back on, worked for a while then stopped with a burning smell. I assume it overheated. Anyway, I cut away more of the weight so the module wasn't such a tight fit and thought I would fit a more expensive module, as I have my suspicions that the LaisDCC modules are a bit marginal with older motors. I ordered a DCC concepts 6 pin module, and the loco worked OK, but stopped on some parts of my layout. When I added the "keep alive" part, I was amazed it worked perfectly not stopping at parts of the layout where it had previously, I was really impressed. So perhaps it is better value to buy more expensive DCC dcoders, though having said that, I have had no issues with the LaisDCC 21 pins variants, but perhaps the locos I fit them to, are better.

[jane1707819582]

lais do different versions ,best to read cv7 before powering up 

1= 500 ma

[ColinB]

Thanks, I didn't know that. It probably explains a lot. I also think their current limiting hardware doesn't work very well. It works short term, but any longer I am pretty sure it blows the chip. That also explains why the 21 pin ones fitted to my newer Bachmanns, I don't have any issues with.

[Fishmanoz]

Why replace the RH screw Colin?  They can’t both be connected to the chassis or there would be a dead short across the motor and nothing would work. 

[ColinB]

It is a split chassis, so the right hand one definitely needs replacing it screws into the chassis. I have just realised the left hand one probably doesn't if you leave out the screw at the end of the sleeve on the otherside of the chassis to the motor brushes. I just do both to be consistant and then there is a remote chance that the sleeved bust end might touch the chassis. It is safewr to insulate both.

[Ruffnut Thorston]

I think that Fishmanoz was thinking of the Hornby Class 6 Ringfield motor...

 

These have two screws holding the brush retainers to the motor block.

 

The left hand one threads into the metal motor / chassis block, which is connected to the track for pickup.

 

The right hand one threads into the plastic faceplate, so is not connected to the track.

[Fishmanoz]

Certainly wasn’t thinking split chassis. Thanks for that Colin, one for the memory bank. 

[Sultan]

The new DCC Concepts ZenV12 Black 218.6decoder  is a 6 x 100ma function decoder with 21 pin direct connection or 8 pin via a fly lead and has built in stay alive! This retails for around £21. Peak Power 1.1 Amp Continuous power 7850ma.

Again, I have no connection with DCC Concepts other than being a satisfied customer.

[Sultan]

That should read 750ma not 7850ma in my previous post.

[ColinB]

After my experience with the previous converted "Mainline" model conversion, I bought a pack of 5 of them, I have 4 models to convert, 2 rebuilt Scot types, 2 Jubilees. One of the Scots works perfectly, but all the others work really badly although they all worked well on DC. In fact on 2 of them the decoder overheated and died (there was smoke coming out the model). One I can attribute to the valve gear "locking up" because of the wheels moving in the plastic spindles but the other I have no idea. I never really realised but obviously in the case of the locked valve gear, the motor must have stalled drawing maximum current. I now realise none of these decoders have stall current protection, on most electronic circuits you have over current protection, but these obviously do not. I cannot understand why the others do not work, I am just assuming there is a compatibilty issue with the output stage in the DCC decoder and the motor. I have checked the current consumption of the motor with an ampmeter and is well within spec for the decoder, the only thing I can think of is the start up current for the motor is very high, which is something you are not going to see on a simple ampmeter. Has anyone any better ideas? I am going to try a different type of decoder to see if it works better.

[96RAF]

If you can jury rig the decoder to a DCC feed then monitor the motor drive output to see if there is any response to throttle or function selection that would at least indicate the decoder was working. You could then turn your attention to the loco as required.

 

This is where a decoder test rig comes in handy - eg ESU - seen here checking directional lights when decoder is working on 9v DC.

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[ColinB]

Yes, in all cases the DCC decoder is working, because the motor tries to move. I think I have found the problem. The one that works OK is drawing slighly less current than the other locos, although we are only talking 100 mA difference. I suspect although these modules work in the 0-6-0 locos I think they are at their limit with the bigger ones with all the valve gear. I have ordered some Zimo modules that have a higher current specification and I will see if these work any better. The trouble is with the older locos on DC you never notice if they are drawing too much current, especially if it is an old H&M controller. I am surprised that these decoders don't have current limiting on the motor output, but given their price I can see why there isn't any. It would be interesting to know if any decoder manufacturer has this it is definitely a marketting feature in my case. The electrical specifications for most of these modules are very vague, mainly focusing on the CV data.

[ColinB]

I received the 6 pin Bachmann decoders and they seem to work fine. It is funny the DCC Concepts ones should work ok as the current is well within their capability, but they surprisingly don't.

[Sultan]

@ColinB  I suggest you take it up with DCC Concepts and from my recent visit to their showrooms in Settle  would imagine they would be very helpful.