James Brake Posted November 9, 2015 Share Posted November 9, 2015 Hi everyone. I was hoping someone could help me with a little problem. Some time ago I bought a Bachmann class 105 DMU and a class 40. Both have DCC on board, however my layout is analog. I asked the dealer if this would cause any problems and I was assured it wouldn't. At the time of the purchase, my layout was being wired up and both locos were left in their boxes for quite some time. Once the layout was running, both locomotives were run in as per the manufacturers instructions. Both seemed to work, although they were somewhat erratic and seemed to need a lot of power just to get moving. Since then their performance has deteriorated significantly. The class 40 changes direction uncommanded when it crosses an electrical section break and the class 105 stops and starts seemingly at will. All of my analog locos work fine. I recently read that combining DCC and analog was a bad idea so today I opened up the class 105 and removed the decoder. When I replaced the DMU on the layout, it was completely dead even though there was good power going to the layout. Can anyone offer an explanation for this behaviour? Is there something obvious which I've forgotten? Any info would be much appreciated. Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted November 9, 2015 Share Posted November 9, 2015 ...I recently read that combining DCC and analog was a bad idea so today I opened up the class 105 and removed the decoder. When I replaced the DMU on the layout, it was completely dead even though there was good power going to the layout. Can anyone offer an explanation for this behaviour? Is there something obvious which I've forgotten? Any info would be much appreciated. Since you do not mention installing a blanking plug in the decoder socket, that's the most likely reason the 105 isn't running. Link to post Share on other sites More sharing options...
chaz Posted November 9, 2015 Share Posted November 9, 2015 Two points - firstly removing the decoder is not enough - you need to add the blanking plug which will connect the pickups and motor together. This should have been supplied with the model on first purchase. Secondly DCC locos always need plenty of volts before they will move on a DC supply. You need to "wake up" the decoder before it can do anything and this typically consumes the first 4 or 5 volts - only then will the motor start to turn. As to a progressive deterioration there is nothing in DCC that might cause this - could it be the wheels need a clean? Hope that's helpful. Chaz Link to post Share on other sites More sharing options...
johnb Posted November 9, 2015 Share Posted November 9, 2015 After removing a decoder you must put a blanking plug into the socket, otherwise as you have found nothing will work! Blanking plugs should be readily obtainable from most model shops, a reputable DCC supplier or Ebay The erratic working of DCC fitted locos on analogue is very frequently the case. The slightest intermittent contact between rail and wheel send 'blips' down the system which the decoder sees as a digital instruction or part of one and gets confused. Best route for you if buying DCC fitted locos is to change the chip for a blanking plug and sell the chip. John Link to post Share on other sites More sharing options...
James Brake Posted November 9, 2015 Author Share Posted November 9, 2015 Thanks for the quick replies. I didn't place a blanking plug over the socket as there wasn't one included in the package for the 105. I haven't removed the decoder from the class 40 yet, though there is a blanking plug included with that one. The class 40 is a 12 plug decoder whereas the 105 is 8. I presume they're easy enough to buy though. Thanks again. Link to post Share on other sites More sharing options...
Brian Posted November 9, 2015 Share Posted November 9, 2015 I think you mean the diesel class 40 loco is 21 pin not 12? Both 8 pin and 21 pin blanking plugs are available. Try DCC supplies or Digitrains.... 21 pin..http://www.digitrains.co.uk/ecommerce/general-accessories/other-items/bp21-21-pin-blanking-plugs-2-pack.aspx http://www.digitrains.co.uk/ecommerce/search/bp8-8-pin-blanking-plugs-2-pack.aspx Edit to add urls Link to post Share on other sites More sharing options...
Pete the Elaner Posted November 9, 2015 Share Posted November 9, 2015 The comments warning about combining DC & DCC refer to having both on the same layout. It is fine until you accidentally run a loco between the 2 sections & it straddles them. A DCC loco should run nicely on DC, as long as the electrical continuity is good & DC operation has not been disabled (It is enabled by default on most, maybe all decoders). Some of the older decoders work poorly on DC, but these were replaced with improved versions several years ago. Link to post Share on other sites More sharing options...
Richard Lee Posted November 10, 2015 Share Posted November 10, 2015 There is one thing that may not be relevant at the moment, but that you should be aware of. I believe that you shouldn't use DCC locomotives with electronic track cleaners for DC, such as the Gaugemaster HF1 and HF2, or the old Relco ones. Edit: The term 'DCC ready' does not mean that something is DCC; it usually means that there is a socket to make DCC fitting easier. By "DCC locomotives" I mean ones with the DCC decoders. Link to post Share on other sites More sharing options...
Phil S Posted November 10, 2015 Share Posted November 10, 2015 Picking up from the last item about Relcos or similar devices intended for analogue and not dcc .... SIMILARLY ensure that the REQUIRED interference suppression capacitor across the track power (included in all commercial power connectors for analogue) iS NOT still fitted when used with DCC ... because DCC is an ac signal, and the capacitor is seen as a (partial) short circuit and corrupts the dcc signal making it unreliable. As mentioned in an earlier reply: when increasing the track voltage, in analogue, for a dcc-fitted loco, NOTHING will happen until about 5V is reached ( 7V on old decoders ) because first it has to power the processor on board .....neglible 'power' is being taken at this stage. THEN the speed will be smoothly increased from 0 to full speed as the controller is increased from this 'mid' position to maximum. .. You should preferably avoid switching direction/polarity while the loco is moving, as this might confuse the decoder ... because it has to look at the track polarity to decide which way IT drives the loco ... always bring the voltage down to 0 first. Link to post Share on other sites More sharing options...
chaz Posted November 10, 2015 Share Posted November 10, 2015 Picking up from the last item about Relcos or similar devices intended for analogue and not dcc .... SIMILARLY ensure that the REQUIRED interference suppression capacitor across the track power (included in all commercial power connectors for analogue) iS NOT still fitted when used with DCC ... because DCC is an ac signal, and the capacitor is seen as a (partial) short circuit and corrupts the dcc signal making it unreliable. As mentioned in an earlier reply: when increasing the track voltage, in analogue, for a dcc-fitted loco, NOTHING will happen until about 5V is reached ( 7V on old decoders ) because first it has to power the processor on board .....neglible 'power' is being taken at this stage. THEN the speed will be smoothly increased from 0 to full speed as the controller is increased from this 'mid' position to maximum. .. You should preferably avoid switching direction/polarity while the loco is moving, as this might confuse the decoder ... because it has to look at the track polarity to decide which way IT drives the loco ... always bring the voltage down to 0 first. Not quite right. I have run O gauge DCC locos on a club layout under DC power. You say "THEN the speed will be smoothly increased from 0 to full speed as the controller is increased from this 'mid' position to maximum." My locos would not run at anything near their maximum speed - in fact with a large layout, with a considerable voltage drop towards the rear of a big oval my V2 came very close to stalling, it's speed having dropped to a walking pace. Even close to the power supply speed was only moderate. Control of a DCC loco with a DC controller will always be less than perfect, OK in extremis but not ideal. When a complete Roco Multimaus DCC system can be bought on German ebay for around £60 why not upgrade? Chaz Link to post Share on other sites More sharing options...
Crosland Posted November 10, 2015 Share Posted November 10, 2015 Picking up from the last item about Relcos or similar devices intended for analogue and not dcc .... SIMILARLY ensure that the REQUIRED interference suppression capacitor across the track power (included in all commercial power connectors for analogue) iS NOT still fitted when used with DCC ... because DCC is an ac signal, and the capacitor is seen as a (partial) short circuit and corrupts the dcc signal making it unreliable. This question is about running DCC locos on a DC layout. The suppression caps in the track connectors can be safely left in place as the track supply is DC. Link to post Share on other sites More sharing options...
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