Stuttering Loco

[BagEndJct]

I took delivery of a good looking Bachmann GWR Pannier with fitted sound last week.

I know this concerns another manufacturer but the problem may be with my RailMaster/eLink setup? So here goes....

The first run was very disappointing. It stutters and, at slow speed, stutters even more and stops. I have run it in as recommended and, although better at speed, at slow speed it's still pretty awful. I contacted their technical help and got the following reply. I'm afraid much of it is Double Dutch to me so I'd be grateful if someone could advise if they are on the right lines and what I should try first?

"Stuttering running

Please make sure you are using a smooth output controller and not one with feedback, as the back EMF on the chip setting will not like it.

It can be resolved for individual layouts.

You can try adjusting CV55 to a value between 5 and 30 to suit.

The actual optimal value for your loco can be found by adjusting this value up or down."

The sound volume was also low and I could hardly hear it above the fan I have in the "Train Shed". But I have upped the relevant CV to its max and that is now acceptable. But not a good start to my long awaited new loco!

Thank you in advance, as ever.

John

[96RAF]

Bachmann change their decoder providers quite often, but their recent factory fitted sound decoders are likely to be ESU Loksound v5, so you may wish to download the manual for it, if one wasn't provided with the loco - or at least a link to an on-line download.

By adjusting the BEMF setting value all you are doing is altering the point at which this control cuts off. BEMF is like cruise control, it compensates for increasing or decreasing load on the motor by increasing or reducing applied 'voltage'.

Not sure why they are talking about a smooth output controller in respect to a DCC scenario. Their decoder decides what the motor gets, although to some extent the quality of that can be adjusted using CVs, but without knowing the exact decoder model and/or having the associated manual it is all guesswork.

[BagEndJct]

I have placed the offending loco on the programming track and am now even more confused. It tells me that it's a Loksound 4 so will have to look up the CVs for that (he pointed me to Loksound 5 instructions).

What there is:

CV55, the one he told me to change, is labelled "Load Control" and it set at 127. The allowed values are 0-255 and the default shows as 32

But...

CV54 also shows as "Load Control" and is set at 007

Then there is

CV57 which is "Load Control Range" .

Help!

PS

Sorry for the double spacing on first post. I wasn't able to go back and amend it.

Mod note: double spacing has been removed via an edit for you.

[BagEndJct]

PS Only just read your post, Rob, after posting the above. I'll look at the Loksound 4 manual. And here it is!

[96RAF]

OK - what you have there is CV56 sets the BEMF cutoff. I would leave that at 255 i.e. on all the time.

They call it KI settings but if you look in a TTS manual it is listed as PI settings and these alter the way the motor behaves as power is applied and as it is decreased.

Unfortunately it is a suck it and see way of setting a motor up. There have been several forum posts about setting up P & I CVs, but I would set them to the values shown in the manual extract and if no good then increase CV54 in steps of 5 until it smooths out as best as possible, then just starts to go lumpy, then back off a bit. Ditto CV55. You may have to fine tune CV54 and CV55 against each other until you get the smoothest you can.

[Rog RJ]

There is an auto tune facility in modern Loksound decoders that may help. See below.

From the DCC Wiki:-

Running Auto Tune

For effective calibration, a length of straight track at least 1.3m long is recommended.

Set CV 54 to the value of 0 (zero)

Leave programming mode

Press F1

The locomotive should begin travelling down the track: It will launch at full speed in the last direction of travel, so ensure it will go the right direction before beginning the process.

At the completion of the Auto Tune process, the locomotive will stop and ring the bell. This should be completed within 1 metre of travel.

Press F1 to silence the bell.

Verification

After the Auto Tune process has completed, verify operation by taking the locomotive on a test run. If further adjustment is needed, set CV53 to a value of 120, and increment or decrement that value as needed.

Known Problems

Some locomotives with factory (OEM) multifunction decoders installed may not work correctly with AutoTune. Rapido Trains' RDC and Royal Hudson may not tune correctly due to their custom programming.

[BagEndJct]

Thanks so much for the advice. Will try these later, or tomorrow, hopefully, and report back.

John

[BagEndJct]

Haha. Just typed this up, then lost it when I pressed POST! Never mind.....

I have had time between jobs getting lunch ready to make some changes - thankfully it's only 29º out there so the kitchen is (relatively) not excessively hot. 41º forecast tomorrow so no cooking planned for then!

Anyway, I am trying Rob's suggestions first. I set CV54 at 55 (having misread his post!) and CV55 at the default, 32. And it's certainly smoother. A couple more tweaks and we might be there. But it's a long process having to power down the track, take the loco off the main track to place it on the programming track. Then power up again. Persuade Railmaster to see the eLink. Change the CVs. Then power down..... etc etc. I never place or remove locos from the track with the power on having blown some decoders in the past!

However, though smoother, it does not accelerate gradually to set speed but takes off at speed and, about a minute after running it, it sped off at top speed out of control. I had to turn off the power to bring it back to its senses.

I think there's a setting somewhere relating to DCC control to avoid these sudden nervous breakdowns. I'll look for it. And I need to look at acceleration settings?

Getting there, thanks to the advice here. Thank you!

[96RAF]

CV29 amongst other things switches off DC running.

Use this calculator to find he required value to program.

http://www.2mm.org.uk/articles/cv29%20calculator.htm

I use a rolling road as my programming track. It has a DPDT (ON-OFF-ON) switch to flip twixt the Track and Prog outputs of my controller, so that I can flip it to Prog, fiddle with CVs, etc, then flip to Track to run those settings.

You can do the same thing with a siding, drive into an isolated siding on Track selection, flip through Off to Prog and do your programming, then flip back to running track again.

The centre OFF selection ensures a definitive break between Track and Prog.

[BagEndJct]

Thank you Rob.

I still have to sort out the start up behaviour. Instead of accelerating smoothly, it does a couple of jerks then takes off probably at the set speed. Before I started altering CVs 54 & 55 it did accelerate OK so it might be something to do with those rather than CV3 ("Acceleration")?

John

[BagEndJct]

I have managed to spend more time on improving the loco but things started getting worse again and I lost my way. I decided to try the "auto" method, recommended above. I was avoiding it as I have a small layout on small board and had visions of the loco shooting off the track.

But it didn't and I ended up with fairly good results. However, I am left with one annoying behaviour. It all-but comes to a stop, then has a double lurch forward. Where should I be looking to cure this, please?

Thank you!

[jane1707819582]

Reduce CV 55 by a value of until the stutter fades .

CV 54 I have found works with the start up of a loco

[BagEndJct]

Thanks. I'll try later. But this has become rather frustrating. I'd expect a new Bachmann loco to work properly out of the box. I have not received very much support from them and will contact the retailer if I fail to get this right!

 

[Rog RJ]

It's pretty normal for DCC fitted locos to need some CV adjustments to get the best out of them. Bachmann locos that used to be fitted with their 36-553 and 36-554 (non sound) decoders seemed to be particularly bad in this respect. Luckily, Hornby decoders don't seem to have this problem apart from some of the TTS models.

[jane1707819582]

Thanks. I'll try later. But this has become rather frustrating. I'd expect a new Bachmann loco to work properly out of the box. I have not received very much support from them and will contact the retailer if I fail to get this right!

 

 

It is not unusual for the need to adjust CV 54 + 55 with any new loco. Every one I have purchased as needed adjustment. Both Bachmann and Hornby. I suspect it is down to the DCC system being used. I have never bottomed the reason, just tinkered the CV until it is how I wanted it. I guess it is harder on the Elite / eLink than the NCE.

[BagEndJct]

Thank you for all your help! I am now almost there. After much meddling with the CVs and a lot of patience(!) I now have a pretty smooth loco which stops without jerking twice afterwards. It is not quite as smooth a stop as I would like and will try another minor adjustment. But compared to how it was out of the box, it's a different loco.

CV54 is now 028 and CV55 as low as 006. The "auto-tune" process helped a lot and I was left with the lurching forward twice after stopping, which is now all but fixed.

I do need to work out CV29 to disable analogue operation as, once again, it took off on its own once more.

By the way, reading the decoder, it tells me it's a Loksound 4 yet the Bachmann paperwork is adamant that it's a Loksound 5. Any ideas on that, please? It may well be a 4 as CV51 is missing.

Thank you again.

[96RAF]

CV29 calculator here

http://www.2mm.org.uk/articles/cv29%20calculator.htm

[BagEndJct]

Thanks Rob. And I just realised that calculator has a "BackCalc" button to work out what's already been set; most useful. I known mine is not the default so must go and check!

[BagEndJct]

I've reduced CV56 even lower to 2. And the loco is now performing pretty smoothly and comes to a nice gentle stop without lurching. So I'm pleased.

However, it once again took off with a mind of its own. I checked CV29 and it's set at 2 so this means analogue operation is already off. Any further ideas on this, please? It scares me to death as previous occurrences of this with other locos have proved to be terminal for the DCC controller!

Thank you, as ever.

[jane1707819582]

Four things to try, if this is happening with with different locos as you suggest.

1. Give the track a good clean .invest in a good track rubber.
2. Check your rail joiners are secure.
3. Is your layout fed with just one connection. Try a multiple wiring ( bus ).
4. Points. If you use point clips check these are secure.

Have you had a controller failure? I would not have thought a DC runaway would damage a controller, another track issue?, intermittent point fault / stray track pin?

[96RAF]

Resetting the controller can often be of benefit but depending upon the device this may lose anything stored in memory e.g. loco names etc.

A simple piece of hardboard used rough side down makes an effective track rubber and doesn’t leave debris to hoover up.

[BagEndJct]

OK thanks. I recently gave the whole board and track a good Spring clean. However, we had a huge storm on Monday and dust will have found its way in and probably onto the track. Also, gecko poo was actually causing a derailment. So if it's down to track grubbiness, I must give it another good clean!

Thank you.

[Rog RJ]

Track & wheel cleanliness is essential for smooth running on both dc & DCC, the difference is that DCC locos are more susceptible to very brief power interruptions (and short circuits) than dc locos.

A dc loco may just carry on with no apparent problem but a DCC loco may be badly affected. This is one reason why stay alive capacitors are often suggested but they are not always the solution.

[rpjallan]

One thing that hasn't been mentioned that I would try is opening up the loco and removing any capacitors that are across the motor. Bachmann Branchline locos seem to usually have a number of these. You can choose to de-solder them or just cut them off. These never improve the running of the loco but can and do cause running issues. The only Bachmann loco that I own that has a Bachmann branded decoder fitted was a terrible runner until I removed the capacitors and now it runs beautifully with no other adjustments.