Ron2070 Posted January 10, 2020 Share Posted January 10, 2020 Hi, I am currently in the process of updating my 15yo Bachmann DCC fitted Cl25 with the intention of fitting lights & sound. I have pulled the motor in order to fit a speaker in the tank and have found a mass of resistors & capacitors attached to the motor, see attached photo. I am planning to use a salvaged V4 sound decoder and would like to know if it's safe to remove the resistors and capacitors from the motor. I have looked at some of my newer loco's and the motors do not have all the c**p that this one has. Thank you Ron Link to post Share on other sites More sharing options...
NIK Posted January 10, 2020 Share Posted January 10, 2020 (edited) Hi Ron, Those things that look like resistors are probably inductors. You may not see inductors and capacitors on other locos as they have been miniaturised and often fitted to the DCC blanking plug. If the resistor like things are inductors and you don't intend on removing your DCC decoder in the future you can remove them and the capacitors. DCC decoders shouldn't need them and some even perform motor control less well if they are present. You can check if they are resistors with a multimeter (loco not touching railway track etc), if they are under a few ohms they are probably inductors. Regards Nick Edited January 10, 2020 by NIK Link to post Share on other sites More sharing options...
Ron2070 Posted January 10, 2020 Author Share Posted January 10, 2020 Hi Nick, Thank you for your advice, I will remove the offending items as I will not be removing the sound decoder once fitted. I can only assume that the early decoders that were used 15 years ago required them to be fitted. Regards Ron Link to post Share on other sites More sharing options...
NIK Posted January 10, 2020 Share Posted January 10, 2020 10 minutes ago, Ron2070 said: Hi Nick, Thank you for your advice, I will remove the offending items as I will not be removing the sound decoder once fitted. I can only assume that the early decoders that were used 15 years ago required them to be fitted. Regards Ron Hi Ron, That's not the reason. DC locos require Electromagnetic Compatibility (EMC) circuitry and in recent decades this has been done by two inductors and one or more capacitors. A DCC ready loco often has the inductors and capacitors in miniature form and are more difficult to identify. I overstated the extent to which those components may be on the DCC blanking plug. However as far as I know no DCC decoders require them to be fitted and I think the opposite is true. Regards Nick 1 Link to post Share on other sites More sharing options...
WIMorrison Posted January 10, 2020 Share Posted January 10, 2020 Many new locos still have these fitted and in the same way that you show in your picture. I have just fitted a decoder into one of these and it has them fitted. These locos come DCC ready and with all wiring for sound included, all you need is a decoder and a speaker. If you loco was DCC Ready or even DCC Fitted then I suggest that you leave them where they are as the OEM clearly designed the loco to work with them Link to post Share on other sites More sharing options...
auxie22 Posted January 11, 2020 Share Posted January 11, 2020 (edited) This circuit is what is known as an LC Filter (sometimes a single capacitor on cheaper locos). It is used to prevent damage to the controller and the reduce the acoustic noise from the motor by stopping high frequencies from entering back into the controller and the motor which can also improve running in PWM DC systems. This is primarily used for DC layouts as some controllers don't use diodes to block back EMF (some controllers even utilize the back EMF voltage in sensorless brushless motors). DCC decoders have these filters built in and so the filters on the motor become superfluous to requirements. You can safely remove them but they (normally) shouldn't cause any significant issues if you kept them in. Edited January 13, 2020 by auxie22 Edited my post as I was tired when writing it so it wasn't entirely accurate 1 Link to post Share on other sites More sharing options...
Crosland Posted January 11, 2020 Share Posted January 11, 2020 15 hours ago, auxie22 said: This circuit is what is known as an LC Filter (sometimes an RC Filter can also be used or even a single capacitor on cheaper locos). It is used to prevent damage and lower the acoustic noise of the motor by stopping high frequencies from entering the motor. This is primarily used for DC layouts as some controllers don't block high frequencies from going to the motor. DCC decoders have these filters built in and so the filters on the motor become superfluous to requirements. You can safely remove them but they (normally) shouldn't cause any significant issues if you kept them. Sorry, but, no.. As already stated, by NIK, these are suppression components to prevent high frequency commutation noise (generated by spark from the brushes) getting out onto the track, radiating, and upsetting next door trying to watch Corrie. These days interference with TV is much less common and more likely to be due to a poor TV aerial and/or downlead. They can safely be removed from any DCC loco and the only advice that will always work is take them out. Some decoders, but not all, are quite happy with them left in. If left in, they can affect BEMF sampling and thus upset speed control. 1 1 Link to post Share on other sites More sharing options...
WIMorrison Posted January 11, 2020 Share Posted January 11, 2020 Can you explain why they are placed in locos that are DCC ready and that without dismantling the loco it would be impossible to remove them? Clearly the OEM expects them to be left in. Leaving then in has absolutely no effect on any of my DCC ready locos Link to post Share on other sites More sharing options...
NIK Posted January 11, 2020 Share Posted January 11, 2020 1 hour ago, WIMorrison said: Can you explain why they are placed in locos that are DCC ready and that without dismantling the loco it would be impossible to remove them? Clearly the OEM expects them to be left in. Leaving then in has absolutely no effect on any of my DCC ready locos Hi, DCC ready means the loco has a DCC socket but no DCC decoder. As supplied it will have a blanking plug fitted so it can be run on DC. So the loco needs the inductors and capacitor in order to be EMC compliant when run without a DCC decoder. They are meant to have no noticeable effect to the driver of a DC model loco. Regards Nick Link to post Share on other sites More sharing options...
WIMorrison Posted January 11, 2020 Share Posted January 11, 2020 I know this, what I want is for @Crosland to explain why he says you must remove these from a motor when the manufacturer of a DCC Ready locomotive has fitted them in a manner that prevents removal without dismantling the loco - to my mind they do not intend that you remove them and I know from practice that leaving them on has no impact upon the operation of the loco, which goes totally against what he says. Link to post Share on other sites More sharing options...
Crosland Posted January 11, 2020 Share Posted January 11, 2020 4 hours ago, WIMorrison said: Can you explain why they are placed in locos that are DCC ready and that without dismantling the loco it would be impossible to remove them? To be truly effective on a DCC ready DC loco (i.e. no decoder) they need to be connected as close as possible to the motor. Putting them on a blanking plug is a compromise, that may cause the loco to fail EMC testing (assuming they are tested). A lot depends on the specifics of the suppression components, the motor and the internal wiring of the loco. 4 hours ago, WIMorrison said: Leaving then in has absolutely no effect on any of my DCC ready locos Tell that to those who have suffered poor running after leaving them connected. 2 hours ago, WIMorrison said: I know this, what I want is for @Crosland to explain why he says you must remove these from a motor Where did I say you must remove them? I was quite clear that some decoders will be quite happy. Therein lies the problem. How do you know in advance ? I'll restate what I said, slightly differently: If you are going to give advice about suppression components "then the only advice that will always work", for all people with all combinations of all motors and all decoders is to remove them. Advising that they can be left in will not always work with some combination of suppression components, decoder and motor. 2 hours ago, WIMorrison said: I know from practice that leaving them on has no impact upon the operation of the loco, which goes totally against what he says. See above. I think you are suffering from confirmation bias. 1 2 Link to post Share on other sites More sharing options...
RMweb Gold Dagworth Posted January 12, 2020 RMweb Gold Share Posted January 12, 2020 5 hours ago, WIMorrison said: I know this, what I want is for @Crosland to explain why he says you must remove these from a motor when the manufacturer of a DCC Ready locomotive has fitted them in a manner that prevents removal without dismantling the loco - to my mind they do not intend that you remove them and I know from practice that leaving them on has no impact upon the operation of the loco, which goes totally against what he says. Probably because @Crosland knows what he is talking about. Removing the components will NEVER make operation worse, leaving them there can in some circumstances. Link to post Share on other sites More sharing options...
WIMorrison Posted January 12, 2020 Share Posted January 12, 2020 This implies that you consider that the OEMs do not know what they are doing and that you know better than them. if the OEM has placed these components anywhere else than on the DC blanking plug then they clearly intend that they are meant to remain on the loco when you convert it to DCC. There is not a single instruction form any manufacturer that you remove anything from anywhere on the loco when converting to DCC. You are simply instructed to remove the blanking plug and insert the decoder and that is all that needs to be done. you do not need to dismantle a loco to remove any other components to convert to DCC. Link to post Share on other sites More sharing options...
Crosland Posted January 12, 2020 Share Posted January 12, 2020 2 hours ago, WIMorrison said: This implies that you consider that the OEMs do not know what they are doing and that you know better than them. The OEMs are fitting components that are required for a DC loco to pass EMC testing. 2 hours ago, WIMorrison said: if the OEM has placed these components anywhere else than on the DC blanking plug then they clearly intend that they are meant to remain on the loco when you convert it to DCC. See my previous reply as to why the blanking plug is not always the ideal place to fit them. 2 hours ago, WIMorrison said: There is not a single instruction form any manufacturer that you remove anything from anywhere on the loco when converting to DCC. You are simply instructed to remove the blanking plug and insert the decoder and that is all that needs to be done. Simple a**e covering. They don't want to tell people to do something that may cause interference. 2 hours ago, WIMorrison said: you do not need to dismantle a loco to remove any other components to convert to DCC. Tell that to the many people who have found otherwise. Isolating an old split chassis loco for example, or rewiring the lighting circuit to get more realistic operation. Please do not assume that your own world view, based on your own loco fleet, is the same as everyone else's, and just accept that other people know form their own experiences that there's a lot more to converting some locos with some decoders than simply plugging in a decoder. I think I've said all I can. Take it or leave it. 1 1 Link to post Share on other sites More sharing options...
WIMorrison Posted January 12, 2020 Share Posted January 12, 2020 @Crosland - please ensure that your criticisms are relevant to the discussion and not your desire to show how knowledgeable you are. I have ONLY ever referred to DCC Ready locomotives, I have not referred to converting locos that are not DCC Ready and therefore do not contain the circuitry to enable the simple plugging in of a decoder. I repeat, on a DCC Ready locomotive you DO NOT need to remove anything other than the DC blanking plug which you replace with the decoder of your choice. Link to post Share on other sites More sharing options...
auxie22 Posted January 12, 2020 Share Posted January 12, 2020 18 hours ago, Crosland said: Sorry, but, no.. As already stated, by NIK, these are suppression components to prevent high frequency commutation noise (generated by spark from the brushes) getting out onto the track, radiating, and upsetting next door trying to watch Corrie. These days interference with TV is much less common and more likely to be due to a poor TV aerial and/or downlead. They can safely be removed from any DCC loco and the only advice that will always work is take them out. Some decoders, but not all, are quite happy with them left in. If left in, they can affect BEMF sampling and thus upset speed control. I stand corrected... Link to post Share on other sites More sharing options...
WIMorrison Posted January 12, 2020 Share Posted January 12, 2020 12 minutes ago, auxie22 said: I stand corrected... Other than in your use of terminology (one letter) you are not wrong. When the loco is DCC Ready you can leave these components connected, especially as they are often buried down in the chassis and without dismantling the entire loco you cannot get to them. Plus if you want to remove the chip, refit the blanking plug, and sell the loco as DCC Ready then you will need to refit these items 1 Link to post Share on other sites More sharing options...
BromsMods Posted January 12, 2020 Share Posted January 12, 2020 Returning to the OP question, about a non DCC ready loco, personally I would just remove the capacitors. 2 Link to post Share on other sites More sharing options...
Butler Henderson Posted January 12, 2020 Share Posted January 12, 2020 If the caps etc are left in situ and on DCC the loco runs erratically / jerks then that is a clear indication that they should be removed. The one issue I have come across on some Bachmann models is that they also act as a motor restraint and if removed the motor is free to rotate as much as it can within the body shell 1 Link to post Share on other sites More sharing options...
Ron2070 Posted January 14, 2020 Author Share Posted January 14, 2020 Good Morning everyone, Apologies for the late reply but unfortunately work has a habit of getting in the way. Thank you to all those who replied to my question, your advice is very much appreciated. Regards Ron 1 Link to post Share on other sites More sharing options...
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