70E Posted June 10, 2011 Share Posted June 10, 2011 I have a Hornby T9 (decoder in tender) and have received today half a dozen Bachmann 8 pin back emf decoders. I have a Lenz 100 and LH 100 throttle. I fitted the decoder and set up the address OK. Loco was extremely jerky/irratic speed up to notch 3 and then on 4 it acted like normal slow crawl and speed increase as throttle notched up. Slowed down ok until notch 3 reached then the irratic behaviour returned. Installed a different decoder and the same thing happened. Is it the loco or the settings on the decoder that need changing. The Bachmann leaflet mentions that the back EMF Cv 54/55 may need to be changed. Never done this before so not quite sure what to do and whether this is the answer. Or dare I say it do I need to remove the capacitors and is there any pictorial instructions on line regarding this particular loco? The other decoders I have fitted today all worked OK in other Hornby locos. On another note I have a Hornby M7 with a decoder fitted. Cannot change the address from 03, have followed Hornbys instructions on their web site but still no joy. Not a big deal using address 3 but would be nice to change if I could. Link to post Share on other sites More sharing options...
Tim Hale Posted June 10, 2011 Share Posted June 10, 2011 Hi, I am guessing that you are using a Bachmann 553, fairly large decoder? One of the problems is that it does not fit in the T9 tender without distorting the tender chassis which in turn leads to poor pick-up and jerky running. Take the tender body and remove the metal weights- two screws- then re-attached the weights to the underside of the tender top with a contact ad hesive and allow to set overnight. This small modification will allow the chassis to sit on the track with all wheels making contact. I set CV5 to between 15-20 for top speed but I don't bother with CV54/55 although some find it useful. The modification has been carried on all my T9's and Bill of this parish and the locos run without any problem. I cannot help you with the M7 as you don't mention the make of decoder but I used a ZTC 216 wireless direct mount and it was superb from the get-go. No messy wires and very easy installation. Tim Link to post Share on other sites More sharing options...
smokebox Posted June 10, 2011 Share Posted June 10, 2011 In my experience the Bachmann decoders often need CVs 54 and 55 adjusting to eliminate the "kangarooing". Work on one CV at a time increasing/decreasing the values in steps of 10 initially and smaller steps as the problem decreases, test running to observe the effect between changes. Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted June 10, 2011 Share Posted June 10, 2011 ... Loco was extremely jerky/erratic speed up to notch 3 and then on 4 it acted like normal slow crawl and speed increase as throttle notched up. Slowed down ok until notch 3 reached then the erratic behaviour returned. Installed a different decoder and the same thing happened. ... dare I say it do I need to remove the capacitors ... That would be my first thought. It will be an orange-brown blob on the wiring. Just cut it off, where the wires emerge from the blob. It is at low speeds where the Back-EMF output of the motor is small that the effect of a capacitor on a back-EMF reading system is proportionately at its' greatest. ...On another note I have a Hornby M7 with a decoder fitted. Cannot change the address from 03, have followed Hornbys instructions on their web site but still no joy. Not a big deal using address 3 but would be nice to change if I could... Was this a 'decoder fitted' M7, so it has a Hornby decoder? What happens when you set the address using the Lenz system having set the programme track on F8 - PROG>DIR>ADR>A _ _ ? Does the loco do the 'little shuffle' on the programme track when you interogate the decoder for its' address in this way? Then what happens when you go back to A _ _ and put in the address you want to change to? Is it possible it is a two digit addressing decoder? Have you tried a decoder reset, and then again attempted to set the address? Sorry for the stream of questions, but more information is necessary to work out what may be going on. Link to post Share on other sites More sharing options...
RMweb Gold RFS Posted June 10, 2011 RMweb Gold Share Posted June 10, 2011 In my experience the Bachmann decoders often need CVs 54 and 55 adjusting to eliminate the "kangarooing". Work on one CV at a time increasing/decreasing the values in steps of 10 initially and smaller steps as the problem decreases, test running to observe the effect between changes. I agree and for this reason replaced my few Bachmann decoders with Lenz Standard+. I even found my T9 jerky at slow speeds with a Hornby R8249 decoder, but with the Lenz decoder its performance is superb even at default CV settings. Worth paying a few pounds extra in my view. Link to post Share on other sites More sharing options...
Trains4U Posted June 10, 2011 Share Posted June 10, 2011 The jerkyness is caused because the Bachmann decoders are set up optimised for motors with flywheels. The lightweight motors used n M7s, T9s and remotored lima models do not have flywheels, so are affected by this. The jerkyness is the result of the decoder sending pulses of power to effectively kick start a flywheel. By adjusting CVs 55 and 56 you can cure the problem. the 36-553 decoders provide excellent performance once configured. Link to post Share on other sites More sharing options...
70E Posted June 11, 2011 Author Share Posted June 11, 2011 Many thanks for the advice guys. After a bit of trail and error I have adjusted CV 54 to 0 and and CV55 to 22 and the T9 works fine. Funnily, I also installed another Bachmann decoder in a new Hornby standard five today and had exactly the same problem so had to do the same again. Yet, I installed three same decoders in Hornby west country/battle of britain yesterday without any problems?! So thanks again for the welcome advice. The M7 has a factory fitted decoder,so I guess it is the cheap and cheerful decoder. I bought it as I had purchased an unfitted M7 previously and made such a lash up of it with bits breaking off everywhere I thought I would go for the easy option. Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted June 11, 2011 RMweb Premium Share Posted June 11, 2011 The M7 has a factory fitted decoder,so I guess it is the cheap and cheerful decoder. I bought it as I had purchased an unfitted M7 previously and made such a lash up of it with bits breaking off everywhere I thought I would go for the easy option. I bought a "DCC fitted" M7 a while back and the decoder was pants. It turned out to be the pre R8249 version although the R8249 was by then the norm. I suppose the stock of old decoders was being sold off in ready fitted locos. I had a moan to Hornby about the fact that it didn't work properly with my set up (Lenz) and they kindly sent me a R8249 replacement. Full marks to Hornby for customer service. PS I used TCS DP2Xs in my T9s, depends which tender (6 wheel or 8 wheel) whether you need the -UK version or not. Keith Link to post Share on other sites More sharing options...
JZ Posted June 18, 2011 Share Posted June 18, 2011 I had this problem with a Bachmann decoder in the Ivatt 2MT. I contacted Bachmann and they replied within a couple of hours. Thank you for your enquiry. You need to adjust the back emf settings to suit the size of the motor as advised on the accompaying paperwork . The Ivatt needs to have adjusted settings although the defaults are fine for the size of motor in the Class 25. For the small motor in the Ivatt, set CV 54 to around 10 to 12 and CV 55 to about 60, adjusting the value until you find your model runs its best. Regards Richard Matthews Service Manager Bachmann Europe plc Link to post Share on other sites More sharing options...
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