Stop and Start

Post all your DCC only problems, solutions and discoverys here.
myfirstlayout
Posts: 6
Joined: Fri Oct 15, 2010 3:41 pm

Stop and Start

Postby myfirstlayout » Fri Feb 24, 2012 6:59 pm

I have a new Hornby class 40 (R2938) fitted with a Lenz decoder, using Hornby Elite controller this engine will run all day long pulling 3 coaches on full power. It will also run all day on ¾ power but as soon as I reduce power to ½ or less the engine stops and starts on the track. Any ideas to why this would happen.

Ark Royal
Posts: 102
Joined: Tue Jan 04, 2011 9:11 am

Re: Stop and Start

Postby Ark Royal » Sat Feb 25, 2012 7:37 am

Hi myfirstlayout

3 things spring to mind:

1) dirty track
2) dirty wheels
3) dodgy pickups

Solutions
1) check that your track is clean. One way to do this is to run another loco VERY slowly, and see of it stalls.
2) depends how new it is. Is it a) out of the box yesterday, or b) year or so old
If a) shouldn't be a proble
b) worth giving the wheels a clean
3) same as 2) above

Hope this helps

Chris
If you have found the above helpful, please read my layout thread and offer a comment
viewtopic.php?f=22&t=36868
Chris
Aka Ark Royal Aka HMS Ark Royal V (on other forums)

Bigmet
Posts: 7962
Joined: Tue Aug 14, 2007 2:19 pm

Re: Stop and Start

Postby Bigmet » Sat Feb 25, 2012 10:23 am

Best also to understand the symptoms you are describing.

Clearly everything has the potential to work, there is nothing seriously wrong with the decoder or the loco chassis, or the DCC system come to that.

But DCC decoders are very sensitive to momentary loss of power supply, and that is almost certainly the problem here. When the track power doesn't reach a DCC decoder, it chops off the motor supply, the loco stops, and then if the power is back on to the decoder, it restarts from speed step 0. Running at speed, the loco moves fast enough through whatever the power interruption problems are, that the decoder keeps going. This is what makes it very likely that the trouble is down on the rails, wheel treads and pick ups.

So what you are looking for is anything and everything that gets in the way of good current collection, from rails, wheels, pick ups. It is quite possible that there are multiple contributors: random patches of track dirt on the rails, some wheel treads very dirty, some wipers not making good contact, and maybe even a poor electrical connection or two between the pick ups and the decoder.

Ark Royal
Posts: 102
Joined: Tue Jan 04, 2011 9:11 am

Re: Stop and Start

Postby Ark Royal » Sat Feb 25, 2012 1:29 pm

The best thing to do is to double EVERY variable

so you need:
a second loco
a NEW yard of flexitrack
another controller (DC or DCC, it doesnt matter)

first, try loco 2 at very low speed on your current track with your elete
put something obvious (drawing pin) wherever it stalls
then repeat with the Class 40 and see if it stalls in the same places (there will be a few by chance, but any places with several stallings, clean the track for approx 1ft in each direction (it helps to use different markers/put them on the opposite sides of the track for different locos)

then, try the class 40 on the new bit of track (use several if you have them) with the elete and see it it continues to stall, then do the same with your other loco
if the 40 stalls, but the other doesnt, then the problem is the 40
if they both stall, the problem is the controller

the connect your allternative controller to the your yard of flexitrack, try the class 40 and see it it continues to stall, then do the same with your other loco. if the 40 stalls now it is definitely the loco, if they both stall then either the track is dirty, in which case try with the drawing pins again, or your second controller is dodgy.


once you have ascertained where the problem is, read my next post
If you have found the above helpful, please read my layout thread and offer a comment
viewtopic.php?f=22&t=36868
Chris
Aka Ark Royal Aka HMS Ark Royal V (on other forums)

Ark Royal
Posts: 102
Joined: Tue Jan 04, 2011 9:11 am

Re: Stop and Start

Postby Ark Royal » Sat Feb 25, 2012 1:36 pm

if the problem is the 40, then
a) clean the wheels
b) take the body off and check the pickups
c) use a multimeter or bulb to check that the DCC Chip is receiving power (be VERY careful not to short out the chip)

d) LAST RESORT attach the bulb to the input side of the DCC chip (this may involve soldering, and if it does it will invalidate your warranty, or you may be able to twist the wires round the pick-ups or something (I have never seen the Cl40 so I dont know))
then run the loco slowly with the body off, and see if the bulb flickers. if so, stop the loco immediately, and take a photo of a) where on the track the loco is, and b) what position the wheels are in. then, analyse the photos to see if there are any patterns (like the wheels are always/most times at the same 1 or 2 angles). Then post on here and we will help furture

if the problem is the track, clean it (there are hundreds of ways to do this, so search on here. there is a thread entitled "effortless track cleaning" in the new discoverys forum which has several ideas, but DON'T USE WD40)

if the problem is the elete - ring Hornby or post on here and someone will help
If you have found the above helpful, please read my layout thread and offer a comment
viewtopic.php?f=22&t=36868
Chris
Aka Ark Royal Aka HMS Ark Royal V (on other forums)

User avatar
poliss
Posts: 1661
Joined: Mon Jun 20, 2005 5:28 pm

Re: Stop and Start

Postby poliss » Sat Feb 25, 2012 2:55 pm

DC does not work in the same way as DCC. On DC, when you reduce speed you reduce voltage. On DCC when a loco is at full speed the motor gets 12v all the time. At half speed the motor gets 12v 50% of the time. See http://www.loystoys.com/info/how-dcc-works.html
Depending on the decoder model you may be able to improve slow speed control by adjusting the CVs.

myfirstlayout
Posts: 6
Joined: Fri Oct 15, 2010 3:41 pm

Re: Stop and Start

Postby myfirstlayout » Sun Feb 26, 2012 9:49 am

Thanks for everyone’s help and ideas. I will work through them.


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