Flying Scotsman Misbehaviour

[Clement Matchett]

I posted earlier that my TT Flying Scotsman arrived damaged. But I managed to bend the valve gear back into a state in which, in the last couple of days, it has circled my 2nd oval without problems.

But

When I try to stop it, it goes into a mad sequence of high speed revs and stalls, and I have to grab it and put it on the baseboard to calm it down!

I also have Blink Bonny, and that has circled my track without problems.

I am using a second hand Hornby Select controller, which is similar to that which I use on my beautiful 00 diorama, and in Scotsman, a Gaugemaster Omni decoder. I bought two of those but it behaves the same way with both. Blink Bonny is decoded using a Dapol N18.

I don’t understand why these problems are occurring.

Can anyone help.

I have to say that added to my difficulties with my 3rd radius track, and now with Flying Scotsman, I am pretty unimpressed with TT120 so far. But it is early days.

[dBerriff]

It sounds as if DCC CV values need resetting to match the motor feedback characteristics. I had best leave it to the experts here to suggest suitable values.

[Ghia69]

Have you tried fitting the decoder from blink bonny into the A4 and vice versa. ?

[96RAF]

Let’s put this problem into context. It is not a TT problem it is a decoder problem (all scales).

Step one is to reset the errant decoder by writing value 8 to CV8.

If your Select is v1.5 or less then you need to get it updated by return to works at Hornby to be able to write CVs.

Then come back here and start again.

PS - some decoders are better than others. You work it out.

Edit - to remove alleged abuse

[Fishmanoz]

Agree with Db and Ghia but have no knowledge of those decoders and what adjustments might be available.

Also Peter, you are one of the first DCC users of the TT:120 locos so there is nothing to fall back on from others’ usage to get typical motor settings.

Rob, do you know anything here? Although you probably haven’t run HM7000 series on TT:120 yet?

[Clement Matchett]

Thank you 96RAF but I don’t like the tone of your response.

I asked for help, not abuse.

But since you are clearly into aggression, have some back…some companies who supply new locomotives with bent valve gear and set curve track which doesn’t make a circle are rubbish too.

You do some working out yourself!

[96RAF]

TT locos factory fitted with HM7000 decoders will have the correct motor profile set.

OP does not say his locos are DCC-fitted from the factory, but that alien make decoders are fitted, GM and Dapol, neither of which have good rep.

These decoders will likely require adjusting to suit the locos.

Once that is done initially by way of a reset to get them back to basic settings then some help can be given, although I doubt anyone on the forum has much experience of fiddling with motor settings for TT locos yet.

[Rallymatt]

I fitted a GM Next18 to my Piko BR130 via an adapter (it’s Plux16) and my A4.

I have experienced out of control moments on both, so it’s most likely the cheap decoders, £20 isn’t going to mean much in the quality stakes. I have £130 worth of Piko sound decoder on order and I will fit HM7000 decoder to the A4 when it arrives.

In the meantime I did the factory reset (CV8) no change but knocking the VMax down and 1/2 VMax seems to have helped running greatly. But the n on Sunday A4 had a spasm again.

I think the GM decoders are best hit with a hammer and thrown away, lesson learned for me, I won’t buy them again. In my last Railway modelling foray (early 2000’s) I found Lenz were superb but things have moved on, eg sound etc and the motors are quite different. Hopefully what’s on order will be much better

[Too Tall]

Odd, GM appeared to have a good rep when I checked them out, oh well, I have 3 Next18's and one 6 pin, and a Hornby 4 pin (bought for wired chipping), so I guess I'll find out !

[dBerriff]

I had similar problems with a Bachmann-branded decoder in a Bachmann 3F 0-6-0. The problem was that this particular motor in this particular locomotive had different control characteristics to most Bachmann setups. The solution I found after searching the forums was to reset specific CV values for this known, problematic combination.

Unfortunately this is not an area where anyone can give generic advice as different decoders can take a different approach to motor control and can use different CV numbers. You will need to consult the decoder documentation or contact the suppliers to get the settings for small, lightweight motors. Perhaps N-gauge references are a good starting point.

[96RAF]

The problem with these branded decoders is they are bought in and the actual decoder make can change over the years, hence the quality and reliability follows the actual make not the brand.

Then you get such as DCC Concepts who now have their own decoders made and also supply to Rails of Sheffield who market them with RoS branding.

The only safe way is to find a brand that works reliably for you and stick with it until something better comes along.

[TT-Man]

ESU, Lenz and Zimo all seem to have a fairly good reputation. They are not the cheapest, but decoders do seem be an area where you get what you pay for.

All my current fleet of TT, HO and OO models that didn't come with a decoder already fitted (the majority) have ESU LokPilot 5 decoders installed. I have not yet had a problem with these decoders and many different brands of locos.

I always adjust the following CVs to my taste:

CV2 Minimum Speed

CV3 Acceleration

CV4 Deceleration

CV5 Maximum Speed

LokPilot 5s then have a very handy feature in their firmware. You set CV54 to 0 then press Function 1. The loco then rockets down the track for around a metre (distance depends on loco scale) and stops. This allows the decoder to analyse the motors performance. Using that data it automatically then sets many other CVs (including those for BackEMF etc.) which saves a lot of time with experimentation. You can of course still set all those CVs manually.

When a loco comes fitted with a decoder you naturally expect that most of the CV settings will have been customised appropriately. However, I usually find I still need to alter CVs 2-5 to suit my own taste.

[Clement Matchett]

I now have three Gresley Pacific’s circling my 3rd and 2nd radius tracks acceptably, using my second hand Select, and Dapol Imperium decoders. No real problems, but of course not perfect. But anyone familiar with the steam age will recall the shrieking which occured when real locos negotiated tight curves.

As regards the choice of N18 decoder, there are few available. Hornby haven’t got any, and the Zimo N18 ones are hard to come by; Youchoos haven’t got any.

Obviously, I was betting against the odds with the cheap GM ones, since with an old Select, I can’t alter CVS, and without an old Select, I am obliged to use the analogue rubbish which came with my Scotsman set - it produced a most unpleasant noise and wouldn’t readily switch from forward to reverse! It is now landfill.

So I followed Simon, of Simon’s Shed and bought Dapol ones. Thanks, Simon!

I could, of course, have bought a pukka controller, but why would I when according to Hornby, I will be able to do everything with HM7000 at quite low cost.

But, RAF96, won’t the Hornby stuff be bought in too? OK, Hornby is a famous brand, but so is Sainsbury. And their stuff is all bought in, with the variable quality implicit in that.