Petone - Changing Indicator Bulbs

The indicators on the panel diagram and on the desk use 12v ??ma bulbs. This page explains how they are changed when they fail.

This page shows how to replace an indicator bulb.




Consider why a green light may not turn on when a signal lever is cleared:

Red Light Turns Off  If a signal lever is put to the clear position and the red light goes out but the green light does not turn on then the indicator bulb may have failed.

Red Light Remains On  If the signal lever is put to the clear position and the red light remains on then the following possibilities must be considered - a track circuit occupied; points incorrectly set; an opposing signal cleared or the signal is blacked out.

Signal 77 Problem Sometimes the signal 77 lever is put to the clear position, the red light goes out but the green light does not illuminate. A check reveals that the indicator bulb is working and driver reports the signal All Red. This fault was fixed in 2012 - it was a loose connection in a location box.

In this situation must obtain confirmation from the driver that the signal is all red before re-stroking lever - if the indicator bulb has in fact failed then the signal will be put at stop in front of the train.

Replacing An Indicator Bulb  The tool on the left has been used to remove the green bezal (sp??).The tool on the right clamps on to the bulb so that it can be removed from the holder. The new bulb is then inserted.

Replacing an indicator bulb



Last Updated: Sat Dec 15 17:25:07 NZDT 2012

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