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Author Topic: runaway 08 ( on DCC)  (Read 315 times)

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Offline AlanK

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runaway 08 ( on DCC)
« on: May 15, 2020, 10:56:30 PM »
Hi,

Recently purchased 08, (ebay), coreless variant.

Don't have DC circuit, so converted via MX616R (zimo) straight to DCC, however as per the title once i start the train off I have no control.

Its been suggested the pick ups may be to blame.. Does that sound about right?.

Ta

Alan

@AlanK
« Last Edit: May 17, 2020, 11:13:35 AM by Railwaygun »
Returnee to Model Railways after 38 years, last time I was 10 and OO Gauge, now 48 and N gauge.

Online Bealman

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Re: runaway 08
« Reply #1 on: May 15, 2020, 11:06:14 PM »
Jon Voight wasn't driving it, was he?  ;)
Vision over visibility. Bono, U2.

Offline AlanK

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Re: runaway 08
« Reply #2 on: May 15, 2020, 11:07:21 PM »
Jon Voight wasn't driving it, was he?  ;)

*Palms face*, I walked right into that one!
Returnee to Model Railways after 38 years, last time I was 10 and OO Gauge, now 48 and N gauge.

Offline jpendle

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Re: runaway 08
« Reply #3 on: May 15, 2020, 11:26:04 PM »
Hi,

Try turning off DC running in CV29. That sometimes helps.

John P
Check out my layout thread.

Contemporary NW (Wigan Wallgate and North Western)

https://www.ngaugeforum.co.uk/SMFN/index.php?topic=39501.msg476247#msg476247

Offline strain

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Re: runaway 08
« Reply #4 on: May 15, 2020, 11:36:52 PM »
Could be the momentum settings at CV3 and/or CV4 are too high meaning it takes far too long for any acceleration/deceleration.

Online njee20

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Re: runaway 08
« Reply #5 on: May 16, 2020, 07:54:59 AM »
Shouldn’t be that assuming it’s a new decoder.

Turning off DC in CV29 is worth trying. It could be as simple as dirty wheels/pickups, so the signals aren’t being read properly. Or it could be a short somewhere in the installation. can you control the start (and then not stop it), or does it runaway as soon as you put it on the track?

Offline Izzy

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Re: runaway 08
« Reply #6 on: May 16, 2020, 08:20:08 AM »

The motors in these are not coreless I’m afraid, just flat sided cans. No control over the loco seems to suggest lack of communication between the controller and decoder. I would try a re-set first, it might clear the problem.

Izzy

Offline stevewalker

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Re: runaway 08
« Reply #7 on: May 16, 2020, 11:32:27 AM »
I've got a similar problem with a loco that I have just converted, although I sometimes get a bit of low speed control, before it runs away. I have tried two different decoders. Investigation has shown a fair bit of sparking at one brush and a lot of radio noise. When I get a chance (I am refurbing the kitchen at the moment), I will check whether the brush moves freely and if the spring is okay and hopefully the problem will go away.

Offline GrahamB

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Re: runaway 08
« Reply #8 on: May 16, 2020, 03:32:05 PM »
I've got two. One of them developed a similar problem. I hadn't properly insulated the chip from its surroundings and was lucky not to blow the chip. One rewrap later and all was fixed.

Offline jpendle

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Re: runaway 08
« Reply #9 on: May 16, 2020, 03:41:10 PM »

The motors in these are not coreless I’m afraid, just flat sided cans. No control over the loco seems to suggest lack of communication between the controller and decoder. I would try a re-set first, it might clear the problem.

Izzy

Hi,

It's not as simple as that.

I had a CL56 that would start up on its own whenever I got a short on the layout, this was during wiring, and track laying.
All my other locos were fine.
If I took the CL56 from the layout then my Voyager would act as its understudy.  :)

I have also experienced a couple of runaways when operating the layout. Once they have been stopped they work fine without any intervention from me.

The premise is that the decoder sees a momentary DC voltage and thinks that means it should go.

All my locos have Zimo decoders.

I solved the runaways in the fiddle yard by making that a separate power district.

Regards,

John P
Check out my layout thread.

Contemporary NW (Wigan Wallgate and North Western)

https://www.ngaugeforum.co.uk/SMFN/index.php?topic=39501.msg476247#msg476247

Offline AlanK

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Re: runaway 08
« Reply #10 on: May 16, 2020, 03:50:14 PM »
Interesting... My 47 just does that as well, zimo Sound... Good to know I'm not the only one... I'm going to look over the 08 contacts tonight... Its not a runaway when I short rather I lose control once as rarted.. can't be much wrong as these 08s are so simple !!
Returnee to Model Railways after 38 years, last time I was 10 and OO Gauge, now 48 and N gauge.

Offline Dr Al

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Re: runaway 08
« Reply #11 on: May 16, 2020, 07:00:06 PM »
Recently purchased 08, (ebay), coreless variant.

Minor detail point:

There's no coreless drive 08. It's driven by a standard 3 pole cored flat can motor.

Not hugely relevant here, but just a FYI.

Cheers,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

“We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces.”Dr. Carl Sagan

Online njee20

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Re: runaway 08
« Reply #12 on: May 16, 2020, 09:24:30 PM »
I had a CL56 that would start up on its own whenever I got a short on the layout, this was during wiring, and track laying.
All my other locos were fine.
If I took the CL56 from the layout then my Voyager would act as its understudy.  :)

I have also experienced a couple of runaways when operating the layout. Once they have been stopped they work fine without any intervention from me.

The premise is that the decoder sees a momentary DC voltage and thinks that means it should go

That is one manifestation, yes, but that’s different to Izzy’s suggestion. Yours usually resolved by disabling DC running in CV29 as discussed. However, as I said it can also just be dirt that can cause this problem, generally with a different manifestation of ‘running away’. I had a Farish 66 that would do that. It would start, and run (admittedly not very well) but wouldn’t stop until it hit something or you lifted it off the track. Was resolved by a good clean.

The racing off when presented with a short is different; that’s the interpretation of a signal as full DCC. Interestingly I’ve never had it on Zimo decoders, only Digitrax.

You can also just have shorts which mean the loco races off the moment you place it on the track.

 

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