Quote:
Originally Posted by Trev
I can't quite believe it myself John, but it happens! There is only one power lead on the entire layout, and that is outside of the loop.
here is a diagram.
\ is a right hand point and / a left.
----------------main line----------------------------------------------
a\-----b\------------loop---------------------------/c
-----------siding-------------------------
When points 'a' and 'c' are switched for 'loop', then 'main line' is isolated. Point 'b' seems to energise both the loop and the siding even if it's just set for the siding. I first noticed it when I was trying to bring a loco out of the siding while leaving a loco standing in the loop. Point 'b' seems to be the errant one, but I won't know for sure until I detach it from 'a' and test it on its own.
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I agree, Point "b" is the one at fault. In fact it appears to have more than one fault. The jumper wires that carry the power across the plastic frog beneath the point appear to be touching. This would normally result in a short circuit but it isn't happening in this case because the point blade/s are not making proper contact with the stock rails either. When you were trying to drive the loco out of the siding with another parked in the loop this is what I think was happening. You set the points in the direction of the siding but the blade did not make proper contact so the current passed down the stock rail and "through" the loco in the loop. It then returned back down the other rail to the points. The poor blade connection stopped it causing a short-circuit but the touching wires (underneath the point) allowed it to travel into the siding and "through" that loco before returing back down the other rail. Both locos have a flow of current through them (in series) and both will therefore try to move.
(The same thing can happen with Electrofrog points if the blades aren't making contact properly.)
Quote:
Originally Posted by Trev
................. I've tried shaving the height of the frog very gradually with a craft blade, but so far its made no difference ....................
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Very risky Trev. Altering the point to suit the 73 might ruin it for other locos.