STG Posted July 19, 2020 Share Posted July 19, 2020 Hi,Recently I fitted an older Hornby Intercity 125 with TTS sound in both Power Cars. The locomotive has a CD motor, and fitted with LED lighting (complete upgrade from the 1980s model).Before fitting TTS, I had stanard 8-pin decoders fitted, and no problems, although I did not have the 8-pin standard decoders fitted for much time.However...Now when I run the train with TTS, it causes the ammeter on my Powercab to freeze (on .13 amps mostly - never changes after). The only other instance of this happening is a short circuit, but the train shows none of the usual characteristics of a short - sounds keep on playing. This has also been triggered when the HST is nowwhere near any points. This is also the only locomotive to trigger it without there being an obvious short.Most of the train is original from the 1980s model, with only the motor change and LED Lighting and rewiring, so could potentially any of old wheels, etc... be to blame?I don't know where to start, I don't know what's happening exactly, or what caused itThis is my only TTS set so any help would be appreciated. Thanks in advance for any help Link to comment Share on other sites More sharing options...
ColinB Posted July 19, 2020 Share Posted July 19, 2020 Is that 0.13 or 13 Amps, if it was 13 Amps you would have one fried HST module. You don't say whether the loco still runs when you get this magic value. If you had a short, nothing would work, the only thing that might be happening is the HST wheels getting stuck in the points frog causing the motor to stall, that would give a high current value. 0.13 wouldn't be right either Ringfields according to my tests consume about 250 milliamps (0.25). Link to comment Share on other sites More sharing options...
STG Posted July 19, 2020 Author Share Posted July 19, 2020 Is that 0.13 or 13 Amps0.13You don't say whether the loco still runs when you get this magic valueThe loco continues running after the ammeter freezes It is a CD Motor Link to comment Share on other sites More sharing options...
jane1707819582 Posted July 19, 2020 Share Posted July 19, 2020 Most likely the motor .DCC is probably over volting the windings look at fitting a dropper diode . Link to comment Share on other sites More sharing options...
96RAF Posted July 19, 2020 Share Posted July 19, 2020 Many of these CD motors are 3v, some 6v and few 12v, very very few are 24v.Unfortunately I haven’t worked a reliable method of finding out what the design max voltage is for any motor, apart from windings resistance versus applied voltage = amps drawn. Is that number viable or not. Link to comment Share on other sites More sharing options...
ColinB Posted July 19, 2020 Share Posted July 19, 2020 The thing is surely they must be 12 volt motors or else his previous decoders would have fried them. DCC drives the motor with a PWM signal, with I assume 0 to 12 volts, so a 3 volt or 6 volt motor would probably over current taking the decoder with it. He says it works properly, it is just the reading wrong on his ammeter. 130 milliamps is not much current, I am sure even a CD mechanism must draw more than that, remember it is hauling an HST, and from my experience quite a heavy load. Anyway the motor is the other side of the DCC decoder as is the leds etc. The only thing sits on the DCC bus is the TTS decoders input stage. Sorry I suspect the ammeter on the Powercab, why you would want one amazes me, it is not DC it is a modulated AC signal. Link to comment Share on other sites More sharing options...
Rog RJ Posted July 20, 2020 Share Posted July 20, 2020 In case there is any misunderstanding, the NCE Powercab has a built in ammeter function that is selectable on the normal display screen./media/tinymce_upload/4961239bf7c26f283888e84050244ef0.jpg When selected, the ammeter is shown instead of the clock. Link to comment Share on other sites More sharing options...
96RAF Posted July 20, 2020 Share Posted July 20, 2020 It can only be measuring the total output current, unless you can tell me that the displayed value changes as different locos are selected. If so that is too clever for me. @Colin - his other decoders may have had the capability to have been tweaked to limit V-max which is a typically employed fudge to control low voltage motors and high voltage children. Link to comment Share on other sites More sharing options...
STG Posted July 20, 2020 Author Share Posted July 20, 2020 unless you can tell me that the displayed value changes as different locos are selectedYes, sorry - I did forget to mention:The layout on standby draws 0.08 amps out of the 0.13 amps.The ammeter freezes practically as soon as the train pulls away from a station on 0.13 (total layout draw), 0.05 drawn from the actual train. Link to comment Share on other sites More sharing options...
96RAF Posted July 20, 2020 Share Posted July 20, 2020 But is it mesuring total track draw or is it selective - say if you had five locos running could you say what draw each one had by selecting that loco or is it just as I think it must be a summation of all locos currents and the standing current. Link to comment Share on other sites More sharing options...
jane1707819582 Posted July 20, 2020 Share Posted July 20, 2020 Track current total . Link to comment Share on other sites More sharing options...
Rog RJ Posted July 20, 2020 Share Posted July 20, 2020 It's the total current supplied by the Powercab. Link to comment Share on other sites More sharing options...
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