Earl Bathurst Posted August 23, 2013 Share Posted August 23, 2013 Im using the Gaugemaster Opti decoders and I find them really good they may not be upto the standards of say lenz but for my use they are fine, some locos top speed then is not that fast, not that I want scalextric but on express passenger it is a bit slow. When I test the locos on DC the top speed is very fast ( bit to fast really) Im using NCE system, can anyone suggest what to do? Thanks Scott Link to post Share on other sites More sharing options...
Lady_Ava_Hay Posted August 23, 2013 Share Posted August 23, 2013 You will need to investigate whether the decoder is using any built in speed table or not. If it is, top speed is in CV93(?) and top value is 255 and that might be too high. You might need to adjust all the values between 74 and 93 to achieve a smooth transition. If the decoder is NOT using the speed table then you will need to adjust the values of CV's 3 5 and 7 (start, mid, full ). Best done on a programming track and using DecoderPro or similar plus well worth reading the manual to see what the defaults are and checking some CV's to see what value they are. Make notes of every change you make. Most decoders use value 8 in CV8 to make a factory reset but this might adjust other CV's that you are currently quite happy with. In general it is agreed that model speed is usually far too high because we use much sharper radius curves and points than the real thing and such curves and trackwork would be speed restricted in real life. Link to post Share on other sites More sharing options...
smokebox Posted August 23, 2013 Share Posted August 23, 2013 There have been a few complaints recently of slowness with the NCE powercab and it seems that the power supply that comes as standard with more recent systems is putting out a relatively low voltage and it is this that appears to be the cause. Put "nce top speed" into the forum search box to see previous posts on this subject Link to post Share on other sites More sharing options...
RMweb Gold RFS Posted August 23, 2013 RMweb Gold Share Posted August 23, 2013 If the decoder is NOT using the speed table then you will need to adjust the values of CV's 3 5 and 7 (start, mid, full ). The correct CVs for these are 2 6 and 5 (start, mid, full ). Link to post Share on other sites More sharing options...
Adrian Wintle Posted August 23, 2013 Share Posted August 23, 2013 First, try turning off back emf. If that doesnt help and if you haven't meddled with CV2 and CV5, the only way to increase the top speed is to increase the track voltage. Adrian Link to post Share on other sites More sharing options...
10000 Posted August 23, 2013 Share Posted August 23, 2013 Before changing any CV's I would investigate your DCC system . Which NCE are you using? My Powercab with a dealer supplied UK power supply is a bit slower than my Gaugemaster DC system and the NCE SB3a is slightly slower than the Powercab on its own. But I am happy with their speed. The other day I was using a Powercab that had been supplied with the USA supply and a razor adaptor. It was definitely slower than mine added to which the supply was only 1.35 amp. Link to post Share on other sites More sharing options...
Theakerr Posted August 23, 2013 Share Posted August 23, 2013 I was reading the Digitrax literature and it seems that their command unit comes with an as built maximum (DC?) voltage. As I understand it this maximum can be read from the cab unit at start-up. Assuming my understanding is correct then on the unit I am borrowing the maximum available voltage is only 8.5V and for some locos (An A5 with a 50:1 DJH motor & gearbox) may be insufficient to get realistic speeds. The good news is that the Digitrax command unit output voltage can be changed by going inside the casing and does not void the warranty. Link to post Share on other sites More sharing options...
Lady_Ava_Hay Posted August 23, 2013 Share Posted August 23, 2013 I was reading the Digitrax literature and it seems that their command unit comes with an as built maximum (DC?) voltage. As I understand it this maximum can be read from the cab unit at start-up. Assuming my understanding is correct then on the unit I am borrowing the maximum available voltage is only 8.5V and for some locos (An A5 with a 50:1 DJH motor & gearbox) may be insufficient to get realistic speeds. The good news is that the Digitrax command unit output voltage can be changed by going inside the casing and does not void the warranty. Track voltage for DCC is very difficult to manage or measure. Those who have actually conducted tests have suggested that Digitrax equipment has the highest track voltage. Nevertheless the track power that reaches the motor is dictated mainly by the decoder and reduced track power as might be experienced by a low cost or basic command station will dictate how many locos can be run rather than how fast one will go. It is also important to use a matched transformer for the command station. My Digitrax Zephyr ( old model ) runs off 14 volts AC 3amps rated and my Digitrax Super Empiure Builder off 16 volts AC 5 amps rated. Incidentally Digitrax equipment at the more expensive end of the range offers more power than most at 5 amps. Link to post Share on other sites More sharing options...
10000 Posted August 23, 2013 Share Posted August 23, 2013 My initial view of the NCE SB3 which is set to 13.8 volts ( assuming you are using a suitable power supply) was that it was slow on top speed. But after working out the scale top speed I got with a Bachmann Class 47 to be 85 mph I decided it was acceptable because most of what I run would have done most of its journey at less than that. So its always useful to work out the scale speed you get. Link to post Share on other sites More sharing options...
Earl Bathurst Posted August 24, 2013 Author Share Posted August 24, 2013 I am using the NCE power cab. Well my layout is a mainline so you would see express locos going nearer their top speed. If I bought the smart booster or the dumb booster would this have any effect on the running speeds? Link to post Share on other sites More sharing options...
Phil S Posted August 24, 2013 Share Posted August 24, 2013 Yes it might: My experience of this was with the ZTC511 controller - which had software controlled track voltage, and the booster transformer / booster combination, which didn't (It was one reason why they offered 2 different transformers, with slightly differing voltages, but not really explained WHY) As the train passes from 1 power district to the other, the change in track voltage, if it exists (it was higher in my case on the booster), will see an increase in the train speed, as the speed range is a proportion of the track voltage in most decoders. [it is possible that some decoders might use an internal fixed voltage reference - in which case they would be unaffected] My 'current experience' with this is using LGB on the 18V input / 16V track dcc we have with our Roco setup and SMPS, which we also use for our LGB shunting puzzle and indoor (level) layouts - but the greater factor there is our programming the locos down to 1/2 or even 1/4 of full speed, with CV5, to constrain the locos within the 3-4m layouts ... compared to 22-24V track voltage outside in a gently sloping garden. Caution: Some makes of decoder (particularly of USA origin) are only rated to 16V and not the full 24V approx of nmra dcc - the warning being on the packaging/instructions and not in the adverts for the product. I have found this with NCE circuit breakers, for example. They can use cheaper and smaller components if the voltage range is only 16V. By contrast; many European decoders (Lenz,ESU,Zimo etc) are multiprotocol and are rated to 35V [ They have no problems on Marklin etc ] PS: Be wary of dcc voltages measured with diigtal multimeters ! They can vary widely, as they are usually calibrated for a 50-60Hz SINEWAVE, and dcc is a modulated square wave approx 10kHz: My voltages are monitored with a RRampmeter and/or oscilloscope (peak-to-peak/2). '12V dc analogue' controllers from which users may be making comparisons, might well be giving 16 or even 20+ volts output at full settings !! (My H+M DC20 being a case in point - totally unregulated!!) Tri-ang Controllers were marked as upto 16Vdc output in the past. 16V is 'common' with '16Vac', but 12V is underpowered by comparison. Link to post Share on other sites More sharing options...
10000 Posted August 24, 2013 Share Posted August 24, 2013 I am using the NCE power cab. Well my layout is a mainline so you would see express locos going nearer their top speed. If I bought the smart booster or the dumb booster would this have any effect on the running speeds? Its the smart booster you would need to buy. Whether it would be any improvement depends on what voltage you are using now and what the new SB5 puts out. My Powercab as bought uses a 15 volt 2 amp supply so based on the info in the manual( 0.5 volt less goes to track) it puts 14.5 volts to the track. My NCE SB3a puts 13.8 volts to the track so everything is a bit slower than the Powercab on its own. As I said previously that gets me a scale 85mph on a Bachmann class 47 which for me is acceptable as I'm not running 125's, Pendo's etc. So to sum up you will only see an improvement if the SB5 puts more volts to the track than your Powercab. Check the power supply on your Powercab to see what volts and amps it is then deduct 0.5 volt to get your track voltage. Link to post Share on other sites More sharing options...
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