I am just about to install several Walthers/Shinohara “DCC friendly” turnouts. In light of recent posts as to their reliability, I want to test them electrically before comitting them to the layout. I have an ohmmeter. What places should have continuity and what should not? The layout will be DCC.
Thanks for your input,
BB
#1 check the points. There should be “zero” resistance between a point and its adjoining stock rail, no matter what position the points are in. This indicates the jumpering between the points and their stock rails has been done properly. Also, there should be inifinite resistance between the 2 points. If these 2 tests do not hold, the turnout is not “DCC friendly”.
There must be visible rail gaps somewhere between the frog and the points in each rail (the gap is meant to be an electrical open). Ideally, there should be 2 more gaps just beyond the frog at the diverging end of the turnout - but these 2 gaps determine how you wire your track, and not DCC “friendliness” in my mind (others will disagree and insist on all 4 gaps). Lastly, there should be some place to connect a polarity-controlled feeder to the frog to ensure no stalling for small locomotives (again, my prejudice; others will go with totally isolated “dead” frogs, which eliminates need for polarity-controlled feeder).
Thank you sir,
I will do these tests tomorrow. BTW, what source of voltage do you use for the polarity sensitive frog?
BB
Clip a DC set of leads from a DC rectifier, Bruce, sort of a DC programming track. Then test with your meter set for DC…if it is meant to be.
In DCC, a contact on the switch machine or otherwise thrown when the turnout is thrown controls the feed of the frog from one of the 2 DCC rail busses (in normal DC it is usually the adjacent stock rails). A separate SPDT contact is required, can be on the switch machine, the control switch, or on the turnout throw. You need to ensure the correct DCC rail bus is connected for the direction the turnout is thrown. http://www.wiringfordcc.com/switches.htm has some very nice diagrams and more details.
I assume you know not to measure resistance with any voltage on the tracks - everything must be off to use an ohm meter. Otherwise, 2 things can occur. You can release the smoke the factory built into your meter, or wrap the needle around the peg (the latter only happens with analog meters :-).
Fred Wright