Anton Stedman Posted July 17, 2020 Share Posted July 17, 2020 Hello,Sorry, this probably doesnt make much sense but here goes!I have a problem where every now and then my Fowler 2p Class '40626' goes shooting off at top speed suddenly without warning! It is not common but has happened about 4 or 5 times now (in the space of 2 years) I presume it is a fault in the loco because none of my other locos have done it. It was second hand when I brought it and I have had it for about 2 years now. Anyway when this 'top speed' problem happened again, nothing noticably went wrong (e.g. no derailments) but when all had calmed down, the loco would not go further than a few inches and then would just stop and make no noticeable effort to start again. The TTS sound remained ok and on, but the movement stopped. I then noticed that one pickup of the inner wheels of the front bogie had slipped out of place. Could this be held back in place easily or am I jumping to conclusions? As far as I am aware nothing else is wrong, but I thought I would see if anyone could solve the problem without me having to send it in for repair or just let it collect dust...! Also, I will post some pics just as a seperate post so that this doesnt get held up.Thanks in advance,Anton Link to comment Share on other sites More sharing options...
Anton Stedman Posted July 17, 2020 Author Share Posted July 17, 2020 Also, I should add that I have tried getting it to move again a few times recently but no difference. Link to comment Share on other sites More sharing options...
Anton Stedman Posted July 17, 2020 Author Share Posted July 17, 2020 This shows the front bogie of the Fowler 2p. As you can see, one pickup has become slightly disconnected although the solder still holds(luckily for me, as I haven't as yet aquired a soldering iron!)/media/tinymce_upload/ed66f28debd333d56b11020f0af5f9b1.JPGAnother image of the same thing.../media/tinymce_upload/8d0f699de2238f8f17eaaa1794fe5fd0.JPG Link to comment Share on other sites More sharing options...
Howbi Posted July 17, 2020 Share Posted July 17, 2020 The usual reason for this is that the decoder has received a corrupt signal making it think it is on DC so it shoots off...........easily cured by altering CV29 by deducting 4 from the current value ........probably easier to just write a value of 2 to CV29 (unless you use 4 digit addressing).This will disable DC running.......use the CV29 calculator here.......HB Link to comment Share on other sites More sharing options...
96RAF Posted July 18, 2020 Share Posted July 18, 2020 Two things in playhere...1. You need to sort out the power pickup, else all other fixes are suspect. it maybe of advantage to remove the decoder plug and fit a blanking plug, then you can use a 9v battery as power source to get the loco running reliably. It is esential you sort basic loco running out first. 2. Reset the decoder if your controller is capable of doing this. This puts its ducks in a row and you are starting from a know default point. Then as Howard says make sure DC running is disabled in the decoder CV29. Recent TTS and R8249 decoders have this set as default, so just check the value read against the calculator linked above. Link to comment Share on other sites More sharing options...
Anton Stedman Posted July 18, 2020 Author Share Posted July 18, 2020 Well this is all quite interesting... Thanks for your quick replies.I started the layout up again today and nope, still no movement from the 2p Fowler. Not even a start up chuff when I turned up the speed (since it is tts) which I thought was strange because it was responding to all other sounds... Anyway, I have reset the decoder and written 2 to CV29. It was previously at value 6. The decoder reset hasn't appeared to make any difference, but after writing 2 to CV29, the loco did actually start moving again (just for a few seconds) - then it stopped and tried to carry on again but couldn't. Also I should have mentioned every time this starts happening (after it has moved and then stops again) a strange smell seems to come from the engine (quite a strong smell)... could this rule out anything? Also, I tried another thing where instead of leaving the whole loco on the rails I just let the tender pickups on so that the wheels could move freely and that the pickups of the front bogies had no contact with the rails. This didnt have any effect, other than that I found out that it tries to go forward and does, to a certain extent then stops and starts again (the starting chuff also repeats everytime the wheels stop and start again). However, when I try to do this in reverse, the wheels will not move and the tts sound just keeps repeating the start of chuff sequence.Also, at the moment I am not all that keen on taking it apart and also I do not have a blanking plug yet, so I thought I would try all the other suggestions first! Just one other thing.@RAF96When you say "You need to sort out the power pickup, else all other fixes are suspect.". I presume you mean the pickup that I indentified as being 'slipped out of place". When I said this I mean, that it is bent upwards (as my pictures should show when they come through) and it looks as if something like a small dot of glue held it their originally... What could I do to hold this back down?So all in all, I'm afraid so far not much has changed! If not I will try the 9v battery test, and a suppose you have to take out the decoder to eliminate the chance of that being the problem!? Regards,Anton Link to comment Share on other sites More sharing options...
ColinB Posted July 18, 2020 Share Posted July 18, 2020 This is an 4-4-0 configuration, correct me if I am wrong. One of the issues is unless there are pickups on the front bogie it is only one axle on the loco that is of any use as a pickup, as the driving axle has traction tyres. I had loads of issues with my Schools class which is the same configuration. In my case because of the way the loco bounces around the track the Loco to tender pin had a habit of jumping out, so the previous owner had "peened" the pin over so the loco and tender were permanently attached. Unfortunately, this had the effect that the tender did not sit properly on the rails, so the loco didn't work properly, to fix it I extended the drawbar. So in your case, check all the tender pickups are working, basically measure the resistance between wheel and pickup. If the drawbar has those finger connections check that they are making good contact. Check that the tender is sitting nicely on the rails. On these locos, the tender pickups are more critical than on other locos.The shooting off at top speed is an unwelcome feature of TTS, normally you have to disable the DC option. To me it is a bug that needs fixing, but certain members on this forum say I am too critical. Hornby did the "bodge" and simply disabled it, on newer locos. TTS is also more critical of the signal than normal decoders, so will find it losing the DCC signal where other decoders don't. Link to comment Share on other sites More sharing options...
Fishmanoz Posted July 19, 2020 Share Posted July 19, 2020 Cause and effect here Colin. Decoders do not cause DC Runaway, imperfect DCC signal to them does. Some are more sensitive than others. Some become more sensitive after having been subject to a short on the track. And TTS reliability seems poor from the anecdotal on here, with a number of fault modes apparent. Link to comment Share on other sites More sharing options...
Anton Stedman Posted July 19, 2020 Author Share Posted July 19, 2020 I have done some more testing and this may or may not complicate things!First of all I have found that it mostly runs OK with a 9v battery, as in rarely stops with its own accord and when it does that awful smell comes. I enabled DC running by adding 4 to CV29 to allow this to work.With DCC, it seems to be quite intermittent except that it shorts the controller semi-regularly.(hornby select). Like, for example when it started to go round a curve, the controller came up with OL which, obviously means short. Sometimes it runs O.K but has very little control over its speed, e.g. it keeps going faster and slower without me doing anything. Another thing is that it seems to be lacking power and I need to give it a push to start it which never used to happen. Furthermore, it seems to stop running altogether once the smell has come out, but tts sound still works. I am starting to wonder whether it may be a pickup or internal component that is touching something it is not meant to be. That might explain the smell, shorting, and maybe the intermittent running as well... I guess, the best thing is to test it more and be sure of some facts!Anybody got any ideas what this might be before I start opening it up and having no idea what to look for! Link to comment Share on other sites More sharing options...
ColinB Posted July 19, 2020 Share Posted July 19, 2020 No DCC decoders don't cause "run away" but poor software does. Generally the average user is not going to change from DCC to DC in milliseconds, probably more like 10s of seconds, so you just put a timer in the software to exclude the switch to DC operation from DCC if the time is less than a certain value. I used to write embedded code software, believe me it is not difficult. Does your car stop, everytime you switch on the aircon or go past a radio mast, no because someone like me told it not to. Why is it some decoders cope with an intermittant signal better than others, lets face it and decent designer should be using that as part of the design criteria. Fortuanetely, I use decoders that don't seem to have these faults my only exception is the TTS decoders and I only use them because they are good value for the money, so I am willing to accept their faults.Back to the original subject, what you need to do unfortunately, is take the loco apart and check all the soldered connections, I had this sort of fault on a Oxford Adams, but I was unluckier than you, I killed three decoders basically going round bends. What it ended up being was the wheels touching a soldered joint connected to the motor. So basically I was feeding the raw DCC signal to the motor, which virtually always kills the motor. So in your case you need to do that check as soon as possible. It could be the wheel has cut through the insulation on one of the wires, they are very thin. Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted July 20, 2020 Share Posted July 20, 2020 No one seems to be paying attention to the comments about the smell released when the loco stops! To me, any smell like this indicates that the motor is burning out... For whatever reason, the motor is burning...further test running could cause more damage. The loco needs attention before further running, in my opinion. Link to comment Share on other sites More sharing options...
96RAF Posted July 20, 2020 Share Posted July 20, 2020 @Sarah - exactly what I said in point 1 in my earlier post. Find out what is wrong with the loco and fix it before faffing about with the other bits and pieces. I seem to recall one of the locos with a powered bogie was incorrectly wired out of the factory, with bogie wires being connected to the inner pins of the socket. If the loco is out of warranty then its a case of body off and time for some basic inspection and fault finding. If still in warranty then the wise thing is to send it back before dismantling. Link to comment Share on other sites More sharing options...
Anton Stedman Posted July 20, 2020 Author Share Posted July 20, 2020 Yes good point. I didn't fully take in RAF96 first message but yes, I had made sure not to test it again to prevent further damage. I have looked into the tender but not been able to find anything out of place. I might just send it in for repair for the extra cost anyway to save extra damage. Also, as I said in a previous post, the loco is second hand and out of warranty. Ok, it is interesting you say about the possible incorrect wiring out of factory, because this isnt the first problem I have had with this loco's front bogie! Thanks very much for your quick relplies and helpful postsRegards,Anton Link to comment Share on other sites More sharing options...
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