DCC converted train has sound but moves only briefly before needing to be power cycled

[SteveM6]

The decoders rely on feedback from the motor to work correctly. Use them within their design parameters and they are fine.

[Paul-365510]

ah yes, I had overlooked the feedback loop. So I can have sound effects but not synchronised sound... which doesn't sound great (literally).

I take the point about a decoder working within its designed parameters, but the problem I have is that I have an FS and a Hornby HM7000 decoder that are not compatible. I have LaisDCCs which work well in the FS but without sound. I don't want to spent £150 on a Zimo decoder with sound, so unless I just eBay the whole lot and buy a second hand FS with DCC and sound, I don't have a solution. Or maybe that IS the solution :)

[SteveM6]

Have you tried the powerbank from your other loco in FS to see if that helps?

[96RAF]

The TTS sound decoders relied upon BEMF to sort out the chuffs but TXS doesn’t work like that and will happily chuff without a motor. I have an old tender as a sound test rig.

Your poor running is because the TXS profile is set up for a modern can motor not an old ringfield. I suggest you run the auto-calibrate routine to allow the decoder to set its own parameters for the motor. Essentially you set auto-cal using a CV, fire it from F0 and it belts off at max chat for about 2m then jobs done. Loco should run smooth after that.

You are aware that LiaisDCC decoders are at best just reverse engineered knock offs of other makes thus may or my not be of any use at decent control.

[Paul-365510]

I'm loathe to unsolder the LiasDCC - the train is running so smoothly at incredibly low speeds, but maybe I'll install an 8 pin harness to make experiments a little simpler, although there's not that much room in the tender - I should maybe put the harness into the engine, it's presumably empty space in there. I'll try it at some point and report back.

thanks.

[Paul-365510]

great info 96RAF.

I'll try that when I get another HM7000 and harnesses (all ordered).

Yes I was aware that the LaisDCC were cheap knock-offs. I have one because it was in a second hand engine I bought. But cheap and cheerful though it may be, it does work smoothly (in this instance anyway), and it's small and comes pre-wrapped. I don't understand why others come naked and you have to get out the insulating tape...

[Paul-365510]

further update.

Got my hands on a second-hand (but mint) DCC ready Hornby Mallard.

Stuck in an HM7000, did the updates, and loaded the A4 profile. No stay-alive at this point.

It didn't move much - just twitched when throttled up.

a-hah! I thought. Time to try the auto-calibration previously recommended.

Following the manual's recommendations I did a reset first. The app then wanted to update Bluetooth (again) so I let it. The app sat for a few minutes on zero progress on the status bar (which was odd), and then displayed the "remove from track to power cycle" screen. Which I did. Well it seems the BT upgrade failed and now there is no BT at all so I can't use the app with this decoder.

I tried using DCC to do a reset, which seemed to work for the CV values but doesn't help with Bluetooth.

I tried the auto-cal i.e. putting zero into 149, clearing the F0 function etc.

Put on the track, hit F0 and it moved a little bit a few times and then stopped.

A stay-alive may help get it moving (as it did with the J83) but I don't know how to get Bluetooth support back. The manual doesn't cover this, but does anyone know how to do a full factory reset on the HM7000 decoder to restore the old Bluetooth firmware? or have I just blown another £60 :(

I can try contacting Hornby support if that's the last resort.

[96RAF]

I should try running thru’ the troubleshooting document, downloadable from the same place as all the other authoritative guides.

Essentially delete the decoder from the app and start again.

It also makes sense to prove the loco works after fitting the decoder before faffing about changing sound profiles.

[Paul-365510]

unfortunately you can't delete it, if you can't connect to it over BT. or at least I can't find any way to do that - unlink and delete fails because it's not connected.

[Fishmanoz]

Force delete by hitting it 3 times?

[Paul-365510]

ok repeated unlink/deletes did eventually delete it. Thanks for the suggestion.

I could then find it as a resettable device. it took several goes before the reset made it linkable again (and you have to kill the app after every reset or it always reappears as resettable rather than linkable). But even after linking to it again, which you might assume meant it was using Bluetooth, it is still not showing up as connecting on Bluetooth and controllable from the app, only from DCC. And on DCC when I throttle up it just makes a worrying buzzing noise and doesn't move. I've opened a ticket with Hornby...

[Fishmanoz]

Trust you’ve gone to the specific HM. help email so you get straight to George the developer?

[96RAF]

A buzzing noise means the motion is jammed, which is likely half your trouble.

There is an app bug whereby some decoders are ‘discovered’ by keep reappearing in the list as needing a reset, when they should be linkable. Cycling the app clears this, which is a pest but it is getting fixed.

[Paul-365510]

Fishmanoz ...er no. I didn't see that option, just the general support email address. I'll wait for a response, hopefully they'll figure out the best person to deal with it.

96RAF - it moves with the LaisDCC decoder inserted (but in fits and starts, maybe needs a stay-alive) so I don't think the motor itself is jammed, but maybe you meant something else. But I'll wait for Hornby before thrashing around any more.

[Brew Man]

If you wait for a response from general support you could be waiting some time. A fortnight is not unheard of. You'd be better sending the email again to HM customer support.

[SteveM6]

- it moves with the LaisDCC decoder inserted (but in fits and starts, maybe needs a stay-alive) so I don't think the motor itself is jammed, but maybe you meant something else. But I'll wait for Hornby before thrashing around any more.

So you are saying that it doesn’t run smoothly on a LaisDCC decoder and barely at all on HM7K and that it is an ‘older’ loco?

 

 

The first rule of DCC, regardless of decoder our operating system, is that the loco should run impeccably on DC or any inherent faults will be amplified by any DCC system as they are les able to ‘power through’ running issues.

 

 

It occurs to me that your loco is not a good runner in the first place and that the LaisDCC decoder may have a higher tolerance than HM7K when it comes to a high current draw due to a loco fault.

 

 

Go back to basics and sort out the loco on DC - the ‘fits and starts’ are likely to be dirty or bent pickups, dirty wheels/track, knackered motor (weak magnets), fluff and detritus in the gears, split or worn gears, bent valve gear......any of those or a combination is likely to be the root cause of the issue.

 

 

Only once it runs perfectly on DC should you consider adding DCC into the mix.

 

 

[ColinB]

From what I have read it sounds like you have an issue with pickups or dirty track, correct me if I am wrong. Now this is my experience of using a lot of DCC decoders. The HM7000 is not very good if the DCC signal is not perfect, it is probably worse than TTS for that which probably explains why it works with a LaisDCC which in my experience is one of the better DCC decoders at coping with a poor DCC signal. A thing to check is the pickups and anything associated with them. So if it is a tender driven loco the pin that connects the loco to tender. Sometimes the oil gets on the connections to the pickup plate that can cause issues. Do as SteveM6 suggests run it with DC, check that it runs reasonably well and then go from there. It may be a current limit issue but the HM7000 if you read the spec is supposed to source up to an amp although they are a bit too expensive to test it on one of my older Ringfield based locos.

[96RAF]

The HM7K decoders are self protecting against motor overload and the app will even tell you if there has been an overload.

The hardware function outputs are NOT self protecting and it is down to the user to ensure applied loads are kept within limits.

All of this is of course in the famous manual which few ever read properly.

[Paul-365510]

I've read chunks of the manual, and in particular the details around auto-calibration, and it was that process I was attempting to apply. But I've not gone through all 130 pages :)

The trains are all good runners and had been working perfectly on DC for over a year, so we can definitely rule out any problems with dirty track etc. (and I've numerous soldered power connections).

The FS runs beautifully without sound with an LaisDCC decoder, without stay-alive, right down to creeping at 5mph, but does not run at all with the HM7000.

The 0-6-0 and 0-4-0 tanks are working well with the HM7000 as long as I install a stay-alive, without the stay-alive they just twitch and reset after a few mm of movement, but they work fine with the LaisDCC decoders and no stay-alive.

But I fear I'm taking up everyone's time here, and you may be concluding that the problem is me. I don't think it is but I'm tempted to conclude that putting an HM7000 into a pre-DCC loco is a hit and miss affair, and that even in a DCC ready Hornby loco, it's not certain to work without tweaking.

I think maybe I should try an old Hornby TTS, or a modern Bachman, Dapol, Loksound or Zimo. Would anyone like to to recommend the decoder they think is most likely to work, even for me?

[Brew Man]

I can't really see that the problem is related to pre-DCC issues, unless it is current overload, or you have somehow wired it up incorrectly. But as already mentioned, the TXS decoders are capable of drawing up to 1 amp which should be plenty even for an old power hungry motor, and the app should alert you anyway. However, just by way of fault elimination, you could try fitting a TXS decoder into a more recent model. Let us know how your get on.

[Rog RJ]

What power supply are you using? (had a quick scan through earlier posts but didn't see anything)

[ColinB]

No Paul-365510 I doubt it is you, you have covered all the tests I would normally do. I have found that the Zimo decoders work best and I have tried very many Manufacturer types. I have said many times that I didn't think the HM7000 was a game changer, the sound is better than TTS but nowhere near the latest Zimo MS range. I did have an issue with a TTS switching off sound on one of my locos, I tried everything I could think of to fix it, in the end I bought a proper Zimo sound decoder and moved the TTS decoder to another loco where it worked perfectly. The big thing with HM7000 is the Bluetooth connection and the ability to work with a smart phone or pad. For the people that already have DCC it doesn't really give much more than TTS, the sound is a bit better but still no synchronization of chuff rate. The reprogramming option I suppose is useful but generally if you have programmed it, are you ever going to do it again.

[Brew Man]

@rog, the op said in his 3rd post that he'd upgraded to a 4A supply, so that should be OK.

[Rog RJ]

Thanks Brewman.

[Fishmanoz]

One not to try - TTS. TTS will only supply 500mA so less likely to cope with an older loco than TXS.