Sailor Charon Posted December 3, 2009 Share Posted December 3, 2009 I started it off, it ran a little, and stopped, ran a little, and stopped, etc. So I tried to stop it. Turned the speed all the way to 0. It still ran a little, and stopped, ran a little, and stopped. And this is on a piece of track that other engines run well on. Help. Somebody. What can I do? I even tried to put it in reverse. And it still carried on going forwards... Edit: I've taken it off the track, and put it down on another bit of track.... no change. I've turned the power off and on again... no change. Link to post Share on other sites More sharing options...
m.tomlinson Posted December 3, 2009 Share Posted December 3, 2009 could be the dreaded capacitors if using a back emf decoder Link to post Share on other sites More sharing options...
Lady_Ava_Hay Posted December 3, 2009 Share Posted December 3, 2009 I started it off, it ran a little, and stopped, ran a little, and stopped, etc. So I tried to stop it. Turned the speed all the way to 0. It still ran a little, and stopped, ran a little, and stopped. And this is on a piece of track that other engines run well on. Help. Somebody. What can I do? I even tried to put it in reverse. And it still carried on going forwards... Edit: I've taken it off the track, and put it down on another bit of track.... no change. I've turned the power off and on again... no change. What make of decoder? What make of command station? What programming facilities do you have? Have you changed any CV's, if so which? Hard wired or plug? 8 or 21 pin? Link to post Share on other sites More sharing options...
Sailor Charon Posted December 3, 2009 Author Share Posted December 3, 2009 Ok, start at the beginning, it's a CT DCX75N 6 pin decoder. It's a Digitrax Super Chief. I'd changed the start volts, mid volts, and top volts. (Can't remember which CVs those are at the moment) Anyway, I decided to stick it on the programming track. I checked the address, and it had changed - I'm not sure how, because I didn't do it - and was now 255. - It had been 25 - which is why it wouldn't respond. I reset the address, and it is now fine. This isn't the first time that CVs have changed on this chip. There was a time when it hit full speed at speed setting 1 (of 99) and I had to redo the setting of start, mid and top volts. Also, for some reason I can't set the four digit address on it. Ah well... Thanks folks. Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted December 3, 2009 Share Posted December 3, 2009 If it is a recent purchase, and you have installed it in line with makers instructions, I should consider a return as unfit for purpose, either for a replacement or money back. By your description it refuses to accept 4 digit addresses (the implication being that it should have this capability, obviously that needs to be confirmed), and has now twice malfunctioned for no apparent reason with other decoders operating on the same system continuing to work normally. That would be enough evidence for me that it is in some way faulty. Link to post Share on other sites More sharing options...
Dr.Glum Posted December 4, 2009 Share Posted December 4, 2009 In recent sessions running the railway, while the 9F was on the live track (moved or not), did you have any event with a short occurring? I have experienced cases of locos losing their CV settings (usually CV1, but not exclusively) when an accident has caused a short, even when it is not to the loco involved. I've had it with several makes of chip. However, you started you topic with "I started it off, it ran a little, and stopped, ran a little, and stopped, etc.". To me, that cries out pickup problems and the first thing I'd check (to rule it out) is the cleanliness and effectiveness of the pickups. That also leads me to wonder if this is a fairly new loco: I find that they need a lot of use over weeks/months to acheive the same reliabilty in the pickup department as older established locos. One of the joys of DCC! Link to post Share on other sites More sharing options...
RMweb Gold Oldddudders Posted December 4, 2009 RMweb Gold Share Posted December 4, 2009 Oddly, I've had a parallel experience with a CT DCX75S, on an 8-pin plug, also with a Super Chief. The loco, a Hornby M7, had misbehaved massively with its factory decoder, so this should have been a new beginning. On starting in reverse, wonderfully smooth - great! Hit the direction button for forward and the start-stop-wait-start-stop-wait-start began. Tried reverse - brill again. Removed loco from track, applied croc clips to trailing bogie - same result, problem still only in forward. Unplugged decoder, ran loco on Address 0 - faultless in both directions. Replugged decoder - problem solved. Yeah, right. Link to post Share on other sites More sharing options...
Nigelcliffe Posted December 4, 2009 Share Posted December 4, 2009 Ok, start at the beginning, it's a CT DCX75N 6 pin decoder. It's a Digitrax Super Chief. I'd changed the start volts, mid volts, and top volts. (Can't remember which CVs those are at the moment) Anyway, I decided to stick it on the programming track. I checked the address, and it had changed - I'm not sure how, because I didn't do it - and was now 255. - It had been 25 - which is why it wouldn't respond. I reset the address, and it is now fine. This isn't the first time that CVs have changed on this chip. There was a time when it hit full speed at speed setting 1 (of 99) and I had to redo the setting of start, mid and top volts. Also, for some reason I can't set the four digit address on it. Ah well... Thanks folks. I take we're discussing an N gauge 9F, such as Dapol or Minitrix. A DCX75 strikes me as a bit small for a OO 9F. CT's can be funny as to the programming mode (paged, physical, direct, etc.). Can't remember off hand which works, but read the instructions and use that mode. Decoder reset on a CT DCX75 is to set the address (CV1) to zero. (Yes, you read that correctly. The command station will not acknowledge the setting (get a timeout in most cases), but the change should be taken by the chip.) A reset might cure the hickups. Sometimes flipping to the alternative CV set will help a stuck one, sometimes not. (The alternative CV set allows the CT to hold two complete sets of CV's which can be flipped between by changing one bit on one CV; can be handy for a-b comparisons of a large number of changes, or if you have a need to change a loco's behaviour in operations). Just sometimes CT's get stuck internally and need to be left to "calm down". They have an internal capacitor which can hold charge in the chip for a surprisingly long period of time. Just leave off the track for an hour and see what happens. If it won't take a four digit address, then there is a fault in the chip. But make sure the chief is programming in the correct mode for the chip, otherwise things can go screwy. If in doubt, calculate CV17,18 and 29 manually and try entering them one at a time (CV calculators in the "articles" section of the 2mm website, link in my signature). To alter the top speed of the loco, change the track reference voltage (not min/mid/max !); a higher value makes the loco run slower. Arnold Heubsch suggests the CT documentation is probably wrong on the detail, 100 appears to be 100 percent, not nominal 10v. Look at the PWM period (usually set to 134 on newer chips). It can be set higher, though my recent experience is that 134 seems to be right with smaller motors. To deal with running qualities, play with the P and I values, start by reducing both by the same fraction (eg. half each, then half again, etc.). When you find the best pair of values, then adjust I independently. Then consider altering CV2/6 for start and mid speed, or a 28 point speed curve. Add momemtum of choice to CV's 3 and 4. Finally, enable half-speed mode (yard mode) and map it to a function key of your choice. ( Doing all that lot is easy with a computer running JMRI / DecoderPro. I am the current author of the CT definition files for JMRI. ) - Nigel Link to post Share on other sites More sharing options...
Sailor Charon Posted December 4, 2009 Author Share Posted December 4, 2009 In recent sessions running the railway, while the 9F was on the live track (moved or not), did you have any event with a short occurring? I have experienced cases of locos losing their CV settings (usually CV1, but not exclusively) when an accident has caused a short, even when it is not to the loco involved. I've had it with several makes of chip. However, you started you topic with "I started it off, it ran a little, and stopped, ran a little, and stopped, etc.". To me, that cries out pickup problems and the first thing I'd check (to rule it out) is the cleanliness and effectiveness of the pickups. That also leads me to wonder if this is a fairly new loco: I find that they need a lot of use over weeks/months to acheive the same reliabilty in the pickup department as older established locos. One of the joys of DCC! Yes, I have had a few shorts. Usually because I've forgotten which way I set a point (or pair of them) and a train has run into it the wrong way. (D'oh) I'll try and make sure which way the points are before starting anything in future. As for the other, it had been running fine the day before, and this was the first time it's ever done this. I've had it for... you know, I can't quite remember. Oh, and Nigelcliffe, thanks for the info. I'll give that a try, because I tried setting 29 manually, and then using the AD4 setting, and it still didn't work. I've got 3 locos with these chips in (1 fitted by me, 1, fitted by the shop, 1... being fixed because the valve gear fell off.) Link to post Share on other sites More sharing options...
Sailor Charon Posted February 3, 2010 Author Share Posted February 3, 2010 One last update. A couple of days ago, it was running fine, when it suddenly stopped. The first thing I did was check the address, and yes, it had gone to 255. No, no shorts this time. So, I reset it to 25 and it was fine... for a while. Until it stopped again. And this time, it came back with No-D when put on the programming track. And so, I've sent it away to be sorted. I know, I should probably have done it sooner. But I managed to find out when I got it - and it was October last year. Anyway, fingers crossed it works when it comes back. Link to post Share on other sites More sharing options...
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