Everything on model trains, model railroads, model railways, locomotives, model train layouts, scenery, wiring, DCC and more. Enjoy the world's best hobby... model railroading!
DCC Loco Control Problem
Andrew posts:
“I am currently using a Hornby DCC controller, with a GWR Castle class OO locomotive, It starts like it’s supposed to but once it reaches its running speed it suddenly accelerates to as fast as it can, even if I try to slow it down with the controller. It won’t respond until I use the emergency stop. Does anyone have any ideas as to what is happening? I currently have it running on the default number 3 DCC address.”
10 Responses to DCC Loco Control Problem
Leave a Reply
SUBMIT YOUR QUESTION
Download Your Free Catalog
Use Tiny Railroad Micro Controllers
Model Train Help Ebook
Hmmmm. Try giving it an address other than 3.
The number on the loco is as good as any number for the address, too. (Makes it simpler to remember)
Andrew,
I suspect your Hornby controller is defective. To verify this try your locomotive on another DCC layout. If this isn’t possible try another loco equipped with DCC on your layout. If you have access to another DCC layout and your loco performs normally you have your answer. Alternatively if another loco performs correctly on your layout the problem is with your locomotive. The DCC address should not affect the way it behaves. You should only use the default #3 until you have determined the loco is working correctly then you should assign it a unique address. Usually the locos number is used for that purpose.
I had a similar problem using basic self fitted decoders on ‘Smokey Joe’ type chassis (used as the basis for kit built locos) controlled with a Bachmann EZ Command.
In the end, I discovered that it was the radio suppression that caused the problem (a capacitor and possibly a resistor, I think). These can be removed by either snipping the wires or desoldering and removing these resolved the problem for me.
Now for the disclaimer. I’ve just checked online and there are conflicting views as to whether suppression capacitors should be removed when fitting DCC decoders. I’m not going to be drawn into that particular debate as I do not have the knowledge needed to form a view either way. All I can say is that the foregoing worked for me so it seems that some decoders can cope with suppression capacitors and some can’t.
Good luck!
Could be a number of things with DCC control. As already stated the best thing is to test on a known good controller which will determine in which component the issue lies.
An alternative DCC related issue may be certain settings in the decoder settings. I have had issues with decoders that required that the same setting be placed in two registers rather than just one which resulted in all sorts of odd things happening if they were different in both locations. Another thing to check is the PID control settings in the decoder as this determines model performance in top speed, acceleration and load control, it may be referred to as Load control in your decoders instructions.
There are a lot of variables involved in the correct setting up of a DCC decoder and some trains, particularly older ones, do not always work properly “straight out of the box” I had a particularly odd behaviour from a Roco loco that just went to full speed almost as soon as the control was moved off stop – adjustment of the PID parameters corrected that, but it was way different from the standard settings.
I did experience something similar with a home brew DCC++ control system – this boiled down to an incompatibility with the Chinese Arduino Uno I was using and has since been sorted out. It would loose synch with the JMRI software and lock up at whatever the last command had been.
Andrew, I have recently had the same problem with my layout and after investigation found that some of the track power connecting clips were not suitable for DCC locos and the problem was that DCC connectors have no capacitors fitted so I removed the capacitors on the ones which had them fitted and the problem was resolved. May be worth having a look.
If there is a concern about cv configuration in the decoder, then return the decoder to factory defaults ) cv 8 to 8).
Check your configuration also for maximum speed allowed. Set your acceleration and deceleration cv s to 0 and check again.
Do you have a setting for a motor start delay.
Best is factory defaults and start adding your configuration back in as you test.
Remove any “buss snubbers” while testing.
Bob S
If one removes the radio suppression elements, not only will it void the warranty, you will likely put the device out of compliance with RFI regulations. That is illegal, and more pragmatically, you will also find it will create interferences within your home compromising radio and TV reception and possibly other bands like Bluetooth and Wifi.
Thank you everyone. A few things to try now.
It could be a simple problem with cv6 being set too high. cv5 sets the maximum power, 250 I think, cv6 is the mid power setting, set it to around 100 ish and that may solve your problem.