Class 71 decoder issues

[GVS]

I've just bought a new Hornby Class 71 as DCC ready. Ran it on DC, all fine. Fitted a DCConcepts Zen decoder and it ran fine and smooth with the body off, directional lights also OK. When I came to fit the body the chip was too tall (direct fit) shame, but no great issue. I robbed a Hornby decoder out of my Class 37 thinking that would be the answer, but that's when the problems start.

As I have said, all worked well with the Zen, but with the Hornby decoder the loco runs fine in both directions but when I turn the directional lights on, the light come on but the loco wont move. Turn them off and it does. Sometimes the light come on and I cant turn them off and the loco remains stationary until I press the 'stop' button and reset.

I swapped a third decoder into the mix, another Zen, and that works fine. So what I have is a Class 71 which works fine on 2 different Zen decoders but not the Hornby, and my old class 37 works fine, including directional lights, on all 3 decoders.

I'm a bit stumped now. Surely if the Hornby decoder was faulty it wouldn't work in the Class 37 either?! I've read on other threads about re-setting the decoder but I'm not sure if that is a good option, or how to do it.

As regards my equipment, these tests have been done using a Hornby Select controller, updated software was done by Hornby earlier this year so is up-to-date. I also use Railmaster and e-Link on my main layout but haven't tried it on that yet.

I'd welcome your thoughts as to what to do next.

Thanks

Graeme

[ColinB]

From what you say it sounds like a current issue in the Hornby decoder, I can't remember whether the class 71 has leds or bulbs. I have one but I just fitted the decoder and it worked perfectly. I though use Zimo decoders which have a much better specification and drive higher currents. I gave up using Hornby decoders as I had many of them fail when driving my older locos (yes I know it was probably over current) so I started using Zimo ones, which weren't that much dearer than the Hornby ones and worked perfectly every time. I will add I also had lots of issues with the Zen, but perhaps that is just me.

[GVS]

Thanks for the reply ColinB.

Since my earlier post I have swapped another Hornby decoder from yet another loco. Exactly the same scenario - Hornby decoder worked fine in my Class 73 with directional cab lights, but not in the Class 71. My provisional conclusion is therefore that with the 71 working well with the Zen (without the body), but also the Hornby decoders working OK with other locos, there has to be 'working' issue between the 71 and Hornby decoders. I'm not savvy enough to understand the detail of current drain and stuff, but I would have hoped that Hornby products would work together, and would have been appropriately tested during development. Maybe there is something else sinister in my particular loco, and maybe it needs to go back? I'll wait a few days to see if there are any other comments/suggestions before planning my next move. Maybe i'll just source a different, smaller, decoder. Like you I have come away from Hornby decoders in recent times.

It's 36 degrees here (France) so it's time for a cold beer!!

[ColinB]

I must admit I am a bit stumped, generally if there is a current issue the decoder in the case of Hornby ones, the decoder blows up the function output, but for lights we are talking function 0 which might be different to the other function outputs. If I get time tomorrow I will go in the loft (it is horrendous up there at the moment) and dig out my class 71. I can't remember what decoder I used, generally there are always Zimo but I did experiment with other makes early on. My class 71 is one of the early ones.

[Fishmanoz]

Given it’s a new modern loco, there shouldn’t be a load issue. And given it’s working fine on DC, that tends to rule out extra drag from the drive train causing overloading. You might just double check this though.

To reset the decoder, write 8 to CV8 with either the Select or RM. Address will then be 03 and you will need to change it back to your preferred.

[Jupiter 1707822591]

From what you are describing GVS .you have a faulty motor.

If it can be returned then do so before it dies completely .

[GVS]

Thanks to both of you.

My little test track is just a circle of second radius, so not the best to get a true impression of things. I need to clear my main layout of debris - currently doing some landscaping and stuff so its a bit of a tip - and give the loco a good run. Maybe it will loosen up a bit, if not , I think the advise to send it back before it dies completely is a good idea, just a bit more tricky from here in France.

[ColinB]

Why don't you just buy a different decoder say a Zimo and see if it improves it. I checked mine yesterday, runs perfectly with the lights on, but I use Zimo decoders. For £20.00 (it may even be cheaper in France) than sending it back. Then at least you can see if it is a motor fault.

[GVS]

Finally got the Class 71 on my main layout. Seems to run fine with or without lights on the Zen decoder. There seems to be a lot of 'run-on' after throttling back, but i'm thinking that is probably down to the twin flywheels and the fact that I haven't yet done any trimming on the decoder. Overall I'm much happier now, but still a bit annoyed that a new Hornby loco wouldn't run properly on a Hornby decoder, still, 'life's too short.........' as the saying goes.

Thanks for all your helpful comments. I think we can close this topic now.

Best wishes to all

Mod note - thread locked per your request.