Ian Fisher Posted February 1, 2016 Share Posted February 1, 2016 Coming to wire up the final stages of adding a dcc buzz, we decided to try it DC to see how our work has gone. Using a mulitmeter gave no short, yet when we plugged in a gaugemaster it was clicking away. We made several inspections and checks then decided to take out a series if wires just working along a line....and hey presto the short went.. Now the buzz was ok no short. the section of droppers were installed one after another, the droppers looked ok but obviously had some fault any ideas what it might be? Ian Link to post Share on other sites More sharing options...
DCB Posted February 1, 2016 Share Posted February 1, 2016 Sounds like an average gremlin incursion, but the multimeter failing to spot it is interesting. It is probably two faults, multimeter leads often fail when they are bent and work while straight, I have wasted hours due to a faulty multimeter lead or meter. You will get random faults, its a fact of life, dry joints, rails which expand and close up joints then contract again. Track pins which end up in flangeways, loco idler shafts which touch driving wheels, wheels which bridge isolators etc. The smart answer is to ensure that the Bus Bar is divided into sections which you can isolate quickly, I would use switches just as I do with my DC sections, not as many, but to be able to identify the general area of the fault before the soldering iron or wire cutters need to be deployed. Not very obviously you will get more faults with the higher voltage and short circuit current of DCC. And check the trains work every time you make a connection, Ok you can't when its a live frog diamond but it can save a lot of hassle if you find a fault as soon as you have created it. Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted February 1, 2016 RMweb Premium Share Posted February 1, 2016 The continuity tester can sometimes give false readings. Partly because they won't detect a partial short (perhaps 100 ohms or more - I can't remember exactly). Go to the low ohms range - probably around 200 ohms & double check occasionally as you go. Also on some multimeters, the continuity tester times out and so you need to turn the meter, off then on again. How do I know this? Link to post Share on other sites More sharing options...
Paul W Posted February 1, 2016 Share Posted February 1, 2016 And check the trains work every time you make a connection, Having built many a layout in DC and then turned to DCC it was noted that shorts were far more common in DCC than DC. The reason why was explained to me by a quite wise DCC sage and it is because the continuous power fed to the track and the very sensitive nature of the short circuit detectors built into DCC controllers makes it more likely for a short to pop it's head above the parapet. And there are many reasons, quoted in the above post, for this. As also said above it would be a good idea to check a connection at it's earliest possible stage as this will narrow down the potential problem area by a large degree if a short arises. Having adopted this practice I can say it is much easier and less time consuming and frustrating than not checking it till all is completed. Paul Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted February 1, 2016 RMweb Premium Share Posted February 1, 2016 Coming to wire up the final stages of adding a dcc buzz, we decided to try it DC to see how our work has gone. Using a mulitmeter gave no short, yet when we plugged in a gaugemaster it was clicking away. We made several inspections and checks then decided to take out a series if wires just working along a line....and hey presto the short went.. Now the buzz was ok no short. the section of droppers were installed one after another, the droppers looked ok but obviously had some fault any ideas what it might be? Ian Frog Juicer or similar? Conflict between point blade setting & frog switching? Are you using Electrofrog or Insulfrog? Link to post Share on other sites More sharing options...
Ian Fisher Posted February 1, 2016 Author Share Posted February 1, 2016 Sounds like an average gremlin incursion, but the multimeter failing to spot it is interesting. It is probably two faults, multimeter leads often fail when they are bent and work while straight, I have wasted hours due to a faulty multimeter lead or meter. You will get random faults, its a fact of life, dry joints, rails which expand and close up joints then contract again. Track pins which end up in flangeways, loco idler shafts which touch driving wheels, wheels which bridge isolators etc. The smart answer is to ensure that the Bus Bar is divided into sections which you can isolate quickly, I would use switches just as I do with my DC sections, not as many, but to be able to identify the general area of the fault before the soldering iron or wire cutters need to be deployed. Not very obviously you will get more faults with the higher voltage and short circuit current of DCC. And check the trains work every time you make a connection, Ok you can't when its a live frog diamond but it can save a lot of hassle if you find a fault as soon as you have created it. Hi David and thanks for the reply, The buzz is divided into five areas and the mainline spilt into up and down lines, which will be protected in the coming days by boards. We had made running checks to see what was happening and it was an odd few hours hearing the DC gaugemaster just powering on the click...click...click It would look like it was not a short as such as in something making a crossed connection but a few metres of wire which had issues... Link to post Share on other sites More sharing options...
Ian Fisher Posted February 1, 2016 Author Share Posted February 1, 2016 The continuity tester can sometimes give false readings. Partly because they won't detect a partial short (perhaps 100 ohms or more - I can't remember exactly). Go to the low ohms range - probably around 200 ohms & double check occasionally as you go. Also on some multimeters, the continuity tester times out and so you need to turn the meter, off then on again. How do I know this? Thank you Kevin, yes we had done a number of the things you mention as we went and yet landed with our issue..it was powered up last night and the issue had seemed to go...after having snipped out a few "correctly" placed droppers. Yep also had the meter freeze and restart which caused a head scratch... Link to post Share on other sites More sharing options...
Ian Fisher Posted February 1, 2016 Author Share Posted February 1, 2016 Frog Juicer or similar? Conflict between point blade setting & frog switching? Are you using Electrofrog or Insulfrog? Yep we are using them and they went in last night but the fault was before this. the point work is all copper clad and all gapped and short free the issues were on plain line....which makes it even odder as in that district it was plastic based plain line with fishplates and two droppers per metre....four droppers on one side which were very fortunatley by chance found to be at fault... Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted February 1, 2016 RMweb Premium Share Posted February 1, 2016 Yep we are using them and they went in last night but the fault was before this. the point work is all copper clad and all gapped and short free the issues were on plain line....which makes it even odder as in that district it was plastic based plain line with fishplates and two droppers per metre....four droppers on one side which were very fortunatley by chance found to be at fault... Obviously, you weren't holding your mouth right! Don't know why those sort of things happen. Its frustrating when you hit a problem like a short, so you gradually disconnect your work, can't find anything wrong, so gradually reassemble & somehow it works as it should! You've got it working, so quit while ahead! Link to post Share on other sites More sharing options...
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