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If the lighting appears to be OK but a sensor is still ‘in the
dark’, try swapping cables with a working set of sensors
(power down the unit before swapping cables). If the other set
of sensors work, then the problem lies with the sensor cable,
not the TrainSpeed 4 display unit. Dismount the sensor pair
and inspect the connections between the cable and the optic,
and the cable and the connector. Also look to see if the cable
itself has been cut along its length. If you have a damaged
sensor assembly or the swapping of sensors did not work,
contact TCS Inc. for technical assistance.
Another problem that can occur is the unit powers up correctly
but a train does not trigger the sensor properly. This can, on
rare occasions, be caused by too much light (especially on the
larger scales). It can also be caused by a short circuit in the
sensor cable assembly. To check to see if there is too much
light, put the unit in test mode for the sensor in question as
outlined above, and cover the sensor completely and tightly
with a dark opaque material (usually a hand pressed down
firmly will do). If you see a change in the display from ‘L’ to
‘H” then the sensor is working (if there is no change see the
next paragraph). Now remove the cover and roll a train car
across the sensor. If you do not see the display change or it
does not stay ‘H’ while the car is over it then there is too much
light. There are several ways to address this. You can recess
the sensor further down into the mounting hole (even below
the roadbed surface) to try to reduce the amount of light
hitting the sensor. If this doesn’t work you can use some
black paint to reduce the area of the sensor’s lens (ballast can
be piled up around the sensor to do this too). Sometimes the
sensor can pick up some excess light from floor reflections, so
try covering the underside of the mounting hole with black
tape. If these measures do not fix the problem contact TCS
Inc. for technical assistance.
If the above test failed, then the sensor assembly is probably
bad. First, try a different (previously working) sensor cable on