6 pin DCC decoders

[ColinB]

Does anyone know a lot about the internals of a 6 pin decoder. I have noticed that some 6 pin decoders will not drive OO based models even if as in my Bachman tank loco case the standard fitting is 6 pin. I generally lookup the output current, but even when it states it will handle 0.5 amps they quite often won't work, failing to drive the loco (yes they are in the right way round). Now Hornby, Zimo, Bachmann and ESU ones work perfectly, DCC Concepts and AE ones (my latest) don't, they hardly turn the motor. Now in the past I have tried contacting DCC Concepts to find out why but just got, "check the current limits". Well as a retired electronics engineer I did that and it was well within the range. Normally I use 6 pin Zimo ones that work perfectly but currently they aren't available. Any ideas?

[Brew Man]

I just put a Train-O-Matic one in my Hornby Terrier and it is fine. Interestingly most of the ones I looked at were direct plug which I didn't want as they won't fit properly in the Terrier. It needs to be on a harness so it can be folded back. I went for the Train-O-Matic as it was a bit cheaper than Hornby's offering.

[ColinB]

Thanks Brew Man I was wondering if the Train-O-Matic ones had the same issue, having only used 8 pin variant, but from what you say it is ok. So it looks like I will put that one on my list to order. I suppose it depends whether it is an 8 pin one with just a different connector or a unique design for N gauge. I suspect it has to be something to do with current, the DCC Concepts one eventually expired when fitted to the Bachmann Tank engine.

[96RAF]

A 6-pin and an 8-pin decoder have different architecture Colin as the 6-pin one has no blue wire. It gets its common positive from the rails and uses a pair of internal external diodes to rectify it for use on direction lighting which effectively is the only function output they can have.

[ColinB]

That may explain the difference 96RAF, but you are not entirely correct. The Zimo decoders just don't bring out the extra wires but the architecture is the same. Obviously the Hornby and ESU must do the same. Sorry but I am not using the blue wire nor any functions, it is driving a tank engine or are you saying that the voltage regulation is different. Or is it that the good ones use full wave rectification (4 diodes) whereas the others only use two diodes.

[96RAF]

Sorry Colin, finger trouble with auto-correct helping me get it wrong. The decoder has a full bridge internal for its own use, but uses diodes external to rectify the track power picked up for use by lights. Like this schematic.

Image credit - Hornby Hobbies

[ColinB]

As a final finale to this topic, I bought a 6 pin ESU device and I can confirm that it works with my OO gauge Bachmann tank loco, the AE Model one I bought earlier doesn't and I suspect is more for an N gauge loco. No criticism of the AE decoder I am only highlighting the issue in case someone like me tries to use it in an OO gauge loco. As it is blister packed it might be an issue getting your money back.

Generally I use Zimo ones as I like them and they are a lot cheaper, but currently they are an out of stock item.

[dBerriff]

ESU LokPilot 5 decoders, apart from the Basic models, are specified at 1.5A motor current so that might be why that decoder works.

[ColinB]

Unfortunately today it overheated and died without any input from me. It just suddenly stopped and then the "tell tale" smell. It was just doing loops around my layout so obviously not so good overall. It is not rated at 1.5 Amps, that may well be its peak but not the normal running current. I really wish Zimo would get their act together I have had no failures on them and I use an awful lot.

[dBerriff]

That knocks my faith in ESU somewhat. I have a LokPilot 5 in one of my recent locos. The manual clearly states 1.5A continuous motor current, and 2.0A continuous with accessories (Edit: Basic and micro versions 0.75A continuous). Ask for your money back if it does not perform to spec, blister pack or not?

[ColinB]

Happy ending fitted a cheap one off EBay and it works wonderfully. Guy who sold it didn't know what make but I suspect Bachmann. I will do a Manufacturers Id check and find out what it is. It ran happily for about an hour. The only thing that could have made the ESU fail was that the motor connection was awfully close to the chassis with a bit blob of solder (new loco nothing to do with me), so I rewired it. I doubt though that it was that that made it fail but I suppose if the motor moved in motion it could happen.

[ColinB]

My cheap one off EBay ( £15.00 ) is a Zimo, no wonder it works so well. The guy that was selling them didn't know what they were, hence the price. So by a fluke I got exactly what I wanted, shame he sold all four.