checking track with multimeter

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richsam
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Joined: Tue Jan 09, 2007 2:53 pm

checking track with multimeter

Postby richsam » Sat Feb 10, 2018 1:30 pm

guys, im having a serious blond moment.

i just completed wiring droppers to my dcc bus.

im currently checking for shorts, so remind me please,

if i check continuity between the two rails i should not get a beep right? both rails should be isolated? am i correct or am i having a major brain f**t?

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D605Eagle
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Re: checking track with multimeter

Postby D605Eagle » Sat Feb 10, 2018 2:15 pm

If you get a beep between both rails it means you've shorted them out. It should always be open circuit between the two.

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Mountain
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Re: checking track with multimeter

Postby Mountain » Sat Feb 10, 2018 4:14 pm

I think most of us get moments like that at times! :D You can buy little devices to put on the rails to check them. Timbersurf made an impressive version made from adapting a 00 gauge bogie. The one I have (Which I've actually not used as yet) is similar but is made into a small block of plastic and has contacts for rails and the L.E.D.'s on the top side. Not sure who made it as I bought it at a local exhibition. It didnt cost a lot.
On my last layout, I simply used a 12v Christmas light bulb and holder from a broken old set of Christmas lights. If the controller tripped, I'd know there was a short on the section of line I'd just switched in. The layout was built before DCC became popular in Britain so it was wired for cab control.
Enjoying 7mm narrow gauge.

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Roger (RJ)
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Re: checking track with multimeter

Postby Roger (RJ) » Sat Feb 10, 2018 5:22 pm

If you have a controller connected to the bus or the track, it might look like a short circuit on the track, depending on the controller and the way it is set. If the controller has a reversing switch with a Forward-Off-Reverse action it should (usually) be open circuit in the "Off" position and would therefore not affect the reading at the track.
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Bufferstop
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Re: checking track with multimeter

Postby Bufferstop » Sat Feb 10, 2018 5:52 pm

As Roger says a controller (or almost anything else) connected across the track will try get the continuity check to beep. You may have omitted an IRJ somewhere, if not on the V rails of electrofrog points. Then perhaps in a reverse loop. If you can't see anything obvious, connect your tester to the bus and work your way round throwing points if one breaks the short circuit start following rails away from that point, you are looking for anything that might cross connect the rails.
Do you use wires of two different colours for your droppers, make sure they all go to the correct rails.
If you need more help, are you using settrack points, streamline electrofrog or insulfrog. Have you fitted any DCC electrification clips to points, A track plan, (hand drawn and scanned or drawn in Paint is good enough. ) would help, mark where the droppers are and where any IRJs are fitted. First go at wiring can always be a baptism of fire.
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Peterm
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Re: checking track with multimeter

Postby Peterm » Sun Feb 11, 2018 12:24 am

Any loco's on the track or stock on with light's?
Pete.

richsam
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Re: checking track with multimeter

Postby richsam » Sun Feb 11, 2018 7:27 am

all is well again.

an hour and a half of spliting track and the bus and i found the culprit on the last section of track (typical)

all it was was a lousy double straight put in back to front.

thanks for the help folks, god bless the multimeter

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Bufferstop
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Re: checking track with multimeter

Postby Bufferstop » Sun Feb 11, 2018 5:37 pm

A battery powered audible continuity tester attached to the bus whilst laying and connecting the track can be useful, yes you'll make it squeak whilst you are attaching bits, but if it doesn't shut up you'll know the last bit you put in was wrong.
Growing old, can't avoid it. Growing up, forget it!
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