numbskull Posted January 2, 2012 Share Posted January 2, 2012 Hi, I have never experienced this before until today. I have a Prodigy Advance 2, when a short occurs normally, there is a regular "buzzing" from the offending point and power is cut. Tonight, the short was an intense buzzing, much higher frequency than normal, and smoke coming from the front of my Voyager (luckily power was switched off at the plug before it was screwed!). Investigating showed than on a couple of tracks, when shorting with wire, they replicated this intense "buzzing" while the rest of the layout was "normal". There is nothing unique about the track in question I can think of, just odd really. Any ideas either: How to solve? or What causes it? Thanks in advance Kevin Link to post Share on other sites More sharing options...
Edwin_m Posted January 2, 2012 Share Posted January 2, 2012 Techie alert! If this is gobbledygook then please say so, but I think you won't solve this problem without some basic knowledge of electrics. Sounds as if you have too much resistance between your command station and this part of the layout. For example with a 5 amp command station and nomlnally 15 volts track voltage, if there is any more than 3 ohms in the feed plus return then the current through a short will be less than 5 amps but potentially still enough to cause a lot of heat. You can get your own threshold value by dividing the command station voltage by its current rating. You can check this out by disconnecting the command station and linking together the two wires that normally connect from the command station to the layout. Put a multimeter on ohms setting and put the probes on the two rails on various parts of the layout. You are then measuring the resistance from one rail to the command station and back to the other rail. If a few are a lot higher than the rest then there may be a bad connection somewhere and you can investigate further by measuring resistance through various parts of your power feed. If however many resistances are up near the threshold, and they increase the further you get from the command station, then it is likely you have used too thin a wire from the command station out to the track, or perhaps you are relying on the rails to take the power for a long distance. Apart from the obvious solution of replacing with thicker wire (or adding extra parallel wires) you might be able to solve the problem more easily by: - Fitting one or more circuit breakers to reduce the maximum current. This only works if you don't need near the full current, or if you can easily split the layout into electrically separate "power districts" each of which can be fed through a separate circuit breaker. Circuit breakers can also cause problems if you have a reversing module. - Increasing your track voltage. This is not possible with all command stations (don't know about the Prodigy) and can cause other problems, so can only help if the "bad" parts of the layout are only just over the threshold. Whatever you do you should get things so that the command station cuts out immediately if a short occurs anywhere on the layout. This is traditionally done with a coin across the rails, but sounds similar to what you have done with a wire. Was it a Dapol Voyager by any chance? I melted one in a very similar way a few years back. Link to post Share on other sites More sharing options...
Nigelcliffe Posted January 3, 2012 Share Posted January 3, 2012 It might be what Edwin says. Equally, it may just be a short via the pickups of the Voyager (one wheel on turnout frog, one on rail near frog), and the internal resistance of the Voyager is sufficient to not trip the command station. Result is lots of current flowing which will generate heat (15v x 3A = 45W, or a fairly big soldering iron !). Solution, after checking wiring, is to firstly not run into short situations and secondly to consider a lower current circuit breaker. Unfortunately, the PowerShield range is not 100% reliable with the Prodigy; I have a friend who has had very serious problems getting a PowerShield to work correctly with a Prodigy, the makers of the PowerShield have been informed and are investigating the issue. Link to post Share on other sites More sharing options...
Edwin_m Posted January 3, 2012 Share Posted January 3, 2012 I thought about Nigel's second suggestion, especially as if it is a Dapol Voyager the engineering isn't exactly solid, but I don't think it fits with Kevin's comment about repeating the test with a piece of wire. Link to post Share on other sites More sharing options...
RMweb Gold roundhouse Posted January 3, 2012 RMweb Gold Share Posted January 3, 2012 Are the tunouts Peco and if so have they been modified by isolating the frog from the blades? If not then it could be similar problem I had on unmodified turnouts where the blade still made contact with the stock rail when the solenoid had been thrown the other way to the way the turnout was set so the polarity change switch on the turnout was for the other direction, causing a slight short on the blades. Try manually throwing the turnout and see if the problem persits with rolling stock removed from the track. Ian Link to post Share on other sites More sharing options...
numbskull Posted January 3, 2012 Author Share Posted January 3, 2012 Hi guys, The first solution sounds most likely, it is a Bachmann Voyager and the short also occurs on straight sections of track using the coin test (well my piece of wire version). I will have a play tonight if i get time with a new feed directly to the troubled section (should have some 2.5mm cable about somewhere, just to be sure) and report back. If successful, I guess a quick rewire is needed! Thanks for all the help. Kevin Link to post Share on other sites More sharing options...
numbskull Posted January 3, 2012 Author Share Posted January 3, 2012 It seems fixed, thanks guys... Link to post Share on other sites More sharing options...
Edwin_m Posted January 3, 2012 Share Posted January 3, 2012 Glad you have it sorted! Link to post Share on other sites More sharing options...
Phil S Posted January 4, 2012 Share Posted January 4, 2012 Just a last observation: The Bachmann Voyager uses (or used when first released) old-fashioned BULBS for the directional lighting - and when used on DCC these are 'on' for much longer than would be normal on an analogue layout! .. therefore they may melt the adjacent plastic parts - despite the 'metal heat sink' construction around them ... I found the transparent plastic lightguide melted on mine before I eventually got around to replacing them with LEDs. Using LEDs also helps keep overall power consumption down ... because with DCC, coach lighting and other power-consuming effects such as sound become more common. Link to post Share on other sites More sharing options...
numbskull Posted January 7, 2012 Author Share Posted January 7, 2012 Thanks for the heads up Phil, it is on the list for replacement lights, you just bumped it up! Link to post Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.