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Author Topic: Standing start problem  (Read 334 times)

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Offline Corbie

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Standing start problem
« on: February 15, 2020, 11:27:57 AM »
I've got my 6' x 3' oval layout laid and wired, and all working. I have droppers from every piece of track and every point. New Peco code 55 flexitrack, with a new Roco Z21 black controller. I have two new Union Mills locos fitted with Lenz Silver Mini decoders, which work well on another system.
I've a problem with getting the locos moving from a standing start. Once moving, they run along very nicely, even at very low speeds; but once stopped, that's it, unless I give them a little nudge. I wondered if they are not drawing enough current for the initial spike that is needed to get the motor turning- any ideas?
Pre-grouping steam / LNER / early BR.

Offline BobB

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Re: Standing start problem
« Reply #1 on: February 15, 2020, 11:34:56 AM »
Are you sure the track is clean ?

Offline Corbie

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Re: Standing start problem
« Reply #2 on: February 15, 2020, 11:49:52 AM »
Are you sure the track is clean ?

I think so Bob; it is brand new track and I've gone over it with a track rubber. The problem happens anywhere on the track.
Pre-grouping steam / LNER / early BR.

Offline MarshLane

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Re: Standing start problem
« Reply #3 on: February 15, 2020, 11:53:24 AM »
I have two new Union Mills locos fitted with Lenz Silver Mini decoders, which work well on another system.  I wondered if they are not drawing enough current for the initial spike that is needed to get the motor turning- any ideas?

Im not up to speed on Lenz decoders, but on the Zimo ones there is a CV value you can change to give a bigger initial burst of power to get the motor turning.  Might be worth looking through the CV list for the decoder and upping that somewhat. 

The other layout that they worked OK on, was that with the same type and make of controller?

Rich

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Re: Standing start problem
« Reply #4 on: February 15, 2020, 12:11:03 PM »
Im not up to speed on Lenz decoders, but on the Zimo ones there is a CV value you can change to give a bigger initial burst of power to get the motor turning.  Might be worth looking through the CV list for the decoder and upping that somewhat.
Thanks for that suggestion, I'll have a look. CV2 gives minimum starting voltage, and there is also CV3 giving starting delay. Will investigate!
Quote
The other layout that they worked OK on, was that with the same type and make of controller?
Rich
No, it is an ECoS.
Pre-grouping steam / LNER / early BR.

Offline MarshLane

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Re: Standing start problem
« Reply #5 on: February 15, 2020, 12:19:01 PM »
Thanks for that suggestion, I'll have a look. CV2 gives minimum starting voltage, and there is also CV3 giving starting delay. Will investigate!

No, it is an ECoS.

CV2 will be the one you want to look at. CV3 just delays the start - so for example if on a sound chip, the prime mover had to ramp up before any movement occurred, CV3 would allow a realistic reflection of that situation.  For your case I would set CV3 to no delay, but try boosting CV2 - probably in small increments.  Again, I am no expert, but I think most of the Zimo decoder CVVs values go 0 - 255, so if you can find out what it is set at now, then maybe try adding 10%.  Keep adding and trying it until you get movement, but remember (or write down) what the last setting was.

When it does move, if it is a bit fast, go half the difference between the current and last setting.  If its sticking again, then half the value between where you are now and the value that you had where it moved etc...  Its all trial and error - but do let us know how you get on.

Rich

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Re: Standing start problem
« Reply #6 on: February 15, 2020, 12:40:31 PM »
The track may be clean but have you cleaned the loco wheels? You say they move off if nudged, so that still sounds like a dirt problem.

Don't be tempted to lubricate the loco drive wheel axles as they're part of the pickup system on UM locos.
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline martyn

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Re: Standing start problem
« Reply #7 on: February 15, 2020, 02:35:17 PM »
I had a similar problem and found that the Union Mills locos needed about 3.4v to start but would then run down to about 2.7v. When it stopped again, it needed the slight boost to get it turning again, but I found slow speed control was difficult.

But using dc controllers on another layout which put a 'spike' intermittently into the main control voltage, the locos could be run very slowly.

I don't know that much about cv on dcc, so I haven't played withem to try and get smooth starts and slow speed running.

Martyn

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Re: Standing start problem
« Reply #8 on: February 15, 2020, 06:44:41 PM »
If the problem is as @martyn suggests and it's down to "sticky" mechanisms then maybe need to find a decoder which has adjustable BEMF "kick" for starting off.  Not the same as the starting voltage CV.  I have G scale decoders which support this so I would assume similar functionality is available in decoders for N (I don't run DCC in N so cannot advise).

Some old Roco N motors can be very sticky starting.
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Online lil chris

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Re: Standing start problem
« Reply #9 on: February 15, 2020, 07:33:41 PM »
Hi there have you checked that the track is getting good voltage, I use a small tester which you place across the rails. I had a similar problem to this when I first started with dcc with my first layout, I found it was caused by my soldering not being up to standard. If you have a multimeter it will show a reading but not the correct reading but will give you a bit of a guide. Here is a pic of my tester, I have added wires to mine and crocodile clips.
Lil Chris
My new layout here, Irwell Valley Railway. https://www.ngaugeforum.co.uk/SMFN/index.php?topic=47127.0

my old layout was East Lancashire Lines.

Offline Corbie

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Re: Standing start problem
« Reply #10 on: February 15, 2020, 08:12:12 PM »
Thanks for all the suggestions. I will not get a chance to do more investigating tomorrow but will get back to it on Monday and will let you know how I get on.
Pre-grouping steam / LNER / early BR.

Offline Corbie

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Re: Standing start problem
« Reply #11 on: February 17, 2020, 08:10:09 PM »
I did a lot of investigating today. First, checked the locos were working correctly on a small ultra-clean test track with nothing else attached- just the controller. Both worked like a dream, standing starts, 5 mph ticking along, both directions. So no problems with the locos.
Next I tried disconnecting the Z21 from the main track and going back to my old Gaugemaster DC supply, with some DC locos. No problems with standing starts but definitely a variation in power at different points in the track- slowing and quickening slightly. The track is shiny and spotless due to my previous efforts to clean it so I started looking at all the connections underneath the board, one by one. There are over 100. The connectors I'm using (crimp-on flat terminals which plug into a squeezed on socket on the bus, which cuts into the wire) are a bit hit and miss. I found some were not cutting in properly, sometimes due to not angling them right with the pliers, sometimes due to a defect in the "cutter" part. On top of that, after crimping the flat terminals on to the dropper wires, sometimes the flat blade is pushed to one side slightly and then when pushed onto the socket doesn't make electrical contact. going round the track with my new multimeter showed quite a bit of variation, although nowhere had no power.
After a couple of hours of checking and double-checking each one and replacing a couple, things are much better.
I am puzzled that I could get DC locos all the way around without a problem (albeit some noticeable slight variation in speed), but the DCC ones had problems. I expected this to be the other way around. Anyway, the locos are now both working relatively smoothly. I am fully ready to accept that I may be barking up the wrong tree and have somehow accidentally fixed the problem in some other way!
Thanks again for the advice.
Pre-grouping steam / LNER / early BR.

Online lil chris

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Re: Standing start problem
« Reply #12 on: February 17, 2020, 11:09:50 PM »
I am pleased you have made some progress, you do need a good connection with dcc for the signal to get through. I myself prefer soldered connections but I understand your reason for using the suitcase connections. A lot of people do not like them and say they are not reliable. But like you found, you have to make sure you use the correct size for the wire you are using and make sure you crimp them properly. A lot of guys in the USA use them on thier layouts, and some have been using them for years with no problems. Of course the other way of avoiding soldered connections is to use choc block connectors, I am using a mix of those and soldering to tag strips with my new layout.
Lil Chris
My new layout here, Irwell Valley Railway. https://www.ngaugeforum.co.uk/SMFN/index.php?topic=47127.0

my old layout was East Lancashire Lines.

 

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